Commit Graph

176 Commits

Author SHA1 Message Date
Oscar Salvador a08a2ae346 mm,memory_hotplug: allocate memmap from the added memory range
Physical memory hotadd has to allocate a memmap (struct page array) for
the newly added memory section.  Currently, alloc_pages_node() is used
for those allocations.

This has some disadvantages:
 a) an existing memory is consumed for that purpose
    (eg: ~2MB per 128MB memory section on x86_64)
    This can even lead to extreme cases where system goes OOM because
    the physically hotplugged memory depletes the available memory before
    it is onlined.
 b) if the whole node is movable then we have off-node struct pages
    which has performance drawbacks.
 c) It might be there are no PMD_ALIGNED chunks so memmap array gets
    populated with base pages.

This can be improved when CONFIG_SPARSEMEM_VMEMMAP is enabled.

Vmemap page tables can map arbitrary memory.  That means that we can
reserve a part of the physically hotadded memory to back vmemmap page
tables.  This implementation uses the beginning of the hotplugged memory
for that purpose.

There are some non-obviously things to consider though.

Vmemmap pages are allocated/freed during the memory hotplug events
(add_memory_resource(), try_remove_memory()) when the memory is
added/removed.  This means that the reserved physical range is not
online although it is used.  The most obvious side effect is that
pfn_to_online_page() returns NULL for those pfns.  The current design
expects that this should be OK as the hotplugged memory is considered a
garbage until it is onlined.  For example hibernation wouldn't save the
content of those vmmemmaps into the image so it wouldn't be restored on
resume but this should be OK as there no real content to recover anyway
while metadata is reachable from other data structures (e.g.  vmemmap
page tables).

The reserved space is therefore (de)initialized during the {on,off}line
events (mhp_{de}init_memmap_on_memory).  That is done by extracting page
allocator independent initialization from the regular onlining path.
The primary reason to handle the reserved space outside of
{on,off}line_pages is to make each initialization specific to the
purpose rather than special case them in a single function.

As per above, the functions that are introduced are:

 - mhp_init_memmap_on_memory:
   Initializes vmemmap pages by calling move_pfn_range_to_zone(), calls
   kasan_add_zero_shadow(), and onlines as many sections as vmemmap pages
   fully span.

 - mhp_deinit_memmap_on_memory:
   Offlines as many sections as vmemmap pages fully span, removes the
   range from zhe zone by remove_pfn_range_from_zone(), and calls
   kasan_remove_zero_shadow() for the range.

The new function memory_block_online() calls mhp_init_memmap_on_memory()
before doing the actual online_pages().  Should online_pages() fail, we
clean up by calling mhp_deinit_memmap_on_memory().  Adjusting of
present_pages is done at the end once we know that online_pages()
succedeed.

On offline, memory_block_offline() needs to unaccount vmemmap pages from
present_pages() before calling offline_pages().  This is necessary because
offline_pages() tears down some structures based on the fact whether the
node or the zone become empty.  If offline_pages() fails, we account back
vmemmap pages.  If it succeeds, we call mhp_deinit_memmap_on_memory().

Hot-remove:

 We need to be careful when removing memory, as adding and
 removing memory needs to be done with the same granularity.
 To check that this assumption is not violated, we check the
 memory range we want to remove and if a) any memory block has
 vmemmap pages and b) the range spans more than a single memory
 block, we scream out loud and refuse to proceed.

 If all is good and the range was using memmap on memory (aka vmemmap pages),
 we construct an altmap structure so free_hugepage_table does the right
 thing and calls vmem_altmap_free instead of free_pagetable.

Link: https://lkml.kernel.org/r/20210421102701.25051-5-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:26 -07:00
Oscar Salvador 8736cc2d00 drivers/base/memory: introduce memory_block_{online,offline}
Patch series "Allocate memmap from hotadded memory (per device)", v10.

The primary goal of this patchset is to reduce memory overhead of the
hot-added memory (at least for SPARSEMEM_VMEMMAP memory model).  The
current way we use to populate memmap (struct page array) has two main
drawbacks:

a) it consumes an additional memory until the hotadded memory itself is
   onlined and

b) memmap might end up on a different numa node which is especially
   true for movable_node configuration.

c) due to fragmentation we might end up populating memmap with base
   pages

One way to mitigate all these issues is to simply allocate memmap array
(which is the largest memory footprint of the physical memory hotplug)
from the hot-added memory itself.  SPARSEMEM_VMEMMAP memory model allows
us to map any pfn range so the memory doesn't need to be online to be
usable for the array.  See patch 4 for more details.  This feature is
only usable when CONFIG_SPARSEMEM_VMEMMAP is set.

[Overall design]:

Implementation wise we reuse vmem_altmap infrastructure to override the
default allocator used by vmemap_populate.  memory_block structure gains a
new field called nr_vmemmap_pages, which accounts for the number of
vmemmap pages used by that memory_block.  E.g: On x86_64, that is 512
vmemmap pages on small memory bloks and 4096 on large memory blocks (1GB)

We also introduce new two functions: memory_block_{online,offline}.  These
functions take care of initializing/unitializing vmemmap pages prior to
calling {online,offline}_pages, so the latter functions can remain totally
untouched.

More details can be found in the respective changelogs.

This patch (of 8):

This is a preparatory patch that introduces two new functions:
memory_block_online() and memory_block_offline().

For now, these functions will only call online_pages() and offline_pages()
respectively, but they will be later in charge of preparing the vmemmap
pages, carrying out the initialization and proper accounting of such
pages.

Since memory_block struct contains all the information, pass this struct
down the chain till the end functions.

Link: https://lkml.kernel.org/r/20210421102701.25051-1-osalvador@suse.de
Link: https://lkml.kernel.org/r/20210421102701.25051-2-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:26 -07:00
David Hildenbrand e9a2e48e87 drivers/base/memory: don't store phys_device in memory blocks
No need to store the value for each and every memory block, as we can
easily query the value at runtime.  Reshuffle the members to optimize the
memory layout.  Also, let's clarify what the interface once was used for
and why it's legacy nowadays.

"phys_device" was used on s390x in older versions of lsmem[2]/chmem[3],
back when they were still part of s390x-tools.  They were later replaced
by the variants in linux-utils.  For example, RHEL6 and RHEL7 contain
lsmem/chmem from s390-utils.  RHEL8 switched to versions from util-linux
on s390x [4].

"phys_device" was added with sysfs support for memory hotplug in commit
3947be1969 ("[PATCH] memory hotplug: sysfs and add/remove functions") in
2005.  It always returned 0.

s390x started returning something != 0 on some setups (if sclp.rzm is set
by HW) in 2010 via commit 57b552ba0b ("memory hotplug/s390: set
phys_device").

For s390x, it allowed for identifying which memory block devices belong to
the same storage increment (RZM).  Only if all memory block devices
comprising a single storage increment were offline, the memory could
actually be removed in the hypervisor.

Since commit e5d709bb5f ("s390/memory hotplug: provide
memory_block_size_bytes() function") in 2013 a memory block device spans
at least one storage increment - which is why the interface isn't really
helpful/used anymore (except by old lsmem/chmem tools).

There were once RFC patches to make use of "phys_device" in ACPI context;
however, the underlying problem could be solved using different interfaces
[1].

[1] https://patchwork.kernel.org/patch/2163871/
[2] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/lsmem
[3] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/chmem
[4] https://bugzilla.redhat.com/show_bug.cgi?id=1504134

Link: https://lkml.kernel.org/r/20210201181347.13262-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-26 09:41:00 -08:00
Anshuman Khandual 1adf8b468f mm/memory_hotplug: rename all existing 'memhp' into 'mhp'
This renames all 'memhp' instances to 'mhp' except for memhp_default_state
for being a kernel command line option.  This is just a clean up and
should not cause a functional change.  Let's make it consistent rater than
mixing the two prefixes.  In preparation for more users of the 'mhp'
terminology.

Link: https://lkml.kernel.org/r/1611554093-27316-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-26 09:41:00 -08:00
David Hildenbrand b611719978 mm/memory_hotplug: prepare passing flags to add_memory() and friends
We soon want to pass flags, e.g., to mark added System RAM resources.
mergeable.  Prepare for that.

This patch is based on a similar patch by Oscar Salvador:

https://lkml.kernel.org/r/20190625075227.15193-3-osalvador@suse.de

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Juergen Gross <jgross@suse.com> # Xen related part
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Libor Pechacek <lpechacek@suse.cz>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Leonardo Bras <leobras.c@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Julien Grall <julien@xen.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Roger Pau Monné <roger.pau@citrix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Link: https://lkml.kernel.org/r/20200911103459.10306-5-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 11:11:18 -07:00
Joe Perches 948b3edba8 drivers core: Miscellaneous changes for sysfs_emit
Change additional instances that could use sysfs_emit and sysfs_emit_at
that the coccinelle script could not convert.

o macros creating show functions with ## concatenation
o unbound sprintf uses with buf+len for start of output to sysfs_emit_at
o returns with ?: tests and sprintf to sysfs_emit
o sysfs output with struct class * not struct device * arguments

Miscellanea:

o remove unnecessary initializations around these changes
o consistently use int len for return length of show functions
o use octal permissions and not S_<FOO>
o rename a few show function names so DEVICE_ATTR_<FOO> can be used
o use DEVICE_ATTR_ADMIN_RO where appropriate
o consistently use const char *output for strings
o checkpatch/style neatening

Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/8bc24444fe2049a9b2de6127389b57edfdfe324d.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 13:12:07 +02:00
Joe Perches 973c39115c drivers core: Remove strcat uses around sysfs_emit and neaten
strcat is no longer necessary for sysfs_emit and sysfs_emit_at uses.

Convert the strcat uses to sysfs_emit calls and neaten other block
uses of direct returns to use an intermediate const char *.

Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/5d606519698ce4c8f1203a2b35797d8254c6050a.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 13:09:10 +02:00
Joe Perches aa838896d8 drivers core: Use sysfs_emit and sysfs_emit_at for show(device *...) functions
Convert the various sprintf fmaily calls in sysfs device show functions
to sysfs_emit and sysfs_emit_at for PAGE_SIZE buffer safety.

Done with:

$ spatch -sp-file sysfs_emit_dev.cocci --in-place --max-width=80 .

And cocci script:

$ cat sysfs_emit_dev.cocci
@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	sprintf(buf,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	snprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	scnprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	strcpy(buf, chr);
+	sysfs_emit(buf, chr);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len =
-	sprintf(buf,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len =
-	snprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len =
-	scnprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
-	len += scnprintf(buf + len, PAGE_SIZE - len,
+	len += sysfs_emit_at(buf, len,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	...
-	strcpy(buf, chr);
-	return strlen(buf);
+	return sysfs_emit(buf, chr);
}

Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/3d033c33056d88bbe34d4ddb62afd05ee166ab9a.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 13:09:10 +02:00
Wei Yang 178bdbed3e drivers/base/memory: rename base_memory_block_id to memory_block_id
memory_block may have a larger granularity than section, this is why we
have base_section_nr. But base_memory_block_id seems a little
misleading, since there is no larger granularity concept which groups
several memory_block.

What we need here is the exact memory_block_id to a section_nr. Let's
rename it to make it more precise.

Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20200623025701.2016-2-richard.weiyang@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-10 14:38:44 +02:00
Wei Yang 40ba2cde77 drivers/base/memory: init_memory_block() first parameter is not necessary
The first parameter of init_memory_block() is intended to retrieve the
memory_block initiated. But now, we never use it.

Drop it for now.

Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20200623025701.2016-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-10 14:38:43 +02:00
Scott Cheloha 4fb6eabf10 drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup
Searching for a particular memory block by id is an O(n) operation because
each memory block's underlying device is kept in an unsorted linked list
on the subsystem bus.

We can cut the lookup cost to O(log n) if we cache each memory block
in an xarray.  This time complexity improvement is significant on
systems with many memory blocks.  For example:

1. A 128GB POWER9 VM with 256MB memblocks has 512 blocks.  With this
   change  memory_dev_init() completes ~12ms faster and walk_memory_blocks()
   completes ~12ms faster.

Before:
[    0.005042] memory_dev_init: adding memory blocks
[    0.021591] memory_dev_init: added memory blocks
[    0.022699] walk_memory_blocks: walking memory blocks
[    0.038730] walk_memory_blocks: walked memory blocks 0-511

After:
[    0.005057] memory_dev_init: adding memory blocks
[    0.009415] memory_dev_init: added memory blocks
[    0.010519] walk_memory_blocks: walking memory blocks
[    0.014135] walk_memory_blocks: walked memory blocks 0-511

2. A 256GB POWER9 LPAR with 256MB memblocks has 1024 blocks.  With
   this change memory_dev_init() completes ~88ms faster and
   walk_memory_blocks() completes ~87ms faster.

Before:
[    0.252246] memory_dev_init: adding memory blocks
[    0.395469] memory_dev_init: added memory blocks
[    0.409413] walk_memory_blocks: walking memory blocks
[    0.433028] walk_memory_blocks: walked memory blocks 0-511
[    0.433094] walk_memory_blocks: walking memory blocks
[    0.500244] walk_memory_blocks: walked memory blocks 131072-131583

After:
[    0.245063] memory_dev_init: adding memory blocks
[    0.299539] memory_dev_init: added memory blocks
[    0.313609] walk_memory_blocks: walking memory blocks
[    0.315287] walk_memory_blocks: walked memory blocks 0-511
[    0.315349] walk_memory_blocks: walking memory blocks
[    0.316988] walk_memory_blocks: walked memory blocks 131072-131583

3. A 32TB POWER9 LPAR with 256MB memblocks has 131072 blocks.  With
   this change we complete memory_dev_init() ~37 minutes faster and
   walk_memory_blocks() at least ~30 minutes faster.  The exact timing
   for walk_memory_blocks() is  missing, though I observed that the
   soft lockups in walk_memory_blocks() disappeared with the change,
   suggesting that lower bound.

Before:
[   13.703907] memory_dev_init: adding blocks
[ 2287.406099] memory_dev_init: added all blocks
[ 2347.494986] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 2527.625378] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 2707.761977] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 2887.899975] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3068.028318] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3248.158764] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3428.287296] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3608.425357] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3788.554572] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 3968.695071] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160
[ 4148.823970] [c000000014c5bb60] [c000000000869af4] walk_memory_blocks+0x94/0x160

After:
[   13.696898] memory_dev_init: adding blocks
[   15.660035] memory_dev_init: added all blocks
(the walk_memory_blocks traces disappear)

There should be no significant negative impact for machines with few
memory blocks.  A sparse xarray has a small footprint and an O(log n)
lookup is negligibly slower than an O(n) lookup for only the smallest
number of memory blocks.

1. A 16GB x86 machine with 128MB memblocks has 132 blocks.  With this
   change memory_dev_init() completes ~300us faster and walk_memory_blocks()
   completes no faster or slower.  The improvement is pretty close to noise.

Before:
[    0.224752] memory_dev_init: adding memory blocks
[    0.227116] memory_dev_init: added memory blocks
[    0.227183] walk_memory_blocks: walking memory blocks
[    0.227183] walk_memory_blocks: walked memory blocks 0-131

After:
[    0.224911] memory_dev_init: adding memory blocks
[    0.226935] memory_dev_init: added memory blocks
[    0.227089] walk_memory_blocks: walking memory blocks
[    0.227089] walk_memory_blocks: walked memory blocks 0-131

[david@redhat.com: document the locking]
  Link: http://lkml.kernel.org/r/bc21eec6-7251-4c91-2f57-9a0671f8d414@redhat.com
Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Nathan Lynch <nathanl@linux.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rick Lindsley <ricklind@linux.vnet.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Link: http://lkml.kernel.org/r/20200121231028.13699-1-cheloha@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-03 20:09:49 -07:00
David Hildenbrand 5f47adf762 mm/memory_hotplug: allow to specify a default online_type
For now, distributions implement advanced udev rules to essentially
- Don't online any hotplugged memory (s390x)
- Online all memory to ZONE_NORMAL (e.g., most virt environments like
  hyperv)
- Online all memory to ZONE_MOVABLE in case the zone imbalance is taken
  care of (e.g., bare metal, special virt environments)

In summary: All memory is usually onlined the same way, however, the
kernel always has to ask user space to come up with the same answer.
E.g., Hyper-V always waits for a memory block to get onlined before
continuing, otherwise it might end up adding memory faster than
onlining it, which can result in strange OOM situations.  This waiting
slows down adding of a bigger amount of memory.

Let's allow to specify a default online_type, not just "online" and
"offline".  This allows distributions to configure the default online_type
when booting up and be done with it.

We can now specify "offline", "online", "online_movable" and
"online_kernel" via
- "memhp_default_state=" on the kernel cmdline
- /sys/devices/system/memory/auto_online_blocks
just like we are able to specify for a single memory block via
/sys/devices/system/memory/memoryX/state

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-9-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:41 -07:00
David Hildenbrand 862919e568 mm/memory_hotplug: convert memhp_auto_online to store an online_type
...  and rename it to memhp_default_online_type.  This is a preparation
for more detailed default online behavior.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-8-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand 4dc8207bfd drivers/base/memory: store mapping between MMOP_* and string in an array
Let's use a simple array which we can reuse soon.  While at it, move the
string->mmop conversion out of the device hotplug lock.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-4-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand efc978ad0e drivers/base/memory: map MMOP_OFFLINE to 0
Historically, we used the value -1.  Just treat 0 as the special case now.
Clarify a comment (which was wrong, when we come via device_online() the
first time, the online_type would have been 0 / MEM_ONLINE).  The default
is now always MMOP_OFFLINE.  This removes the last user of the manual
"-1", which didn't use the enum value.

This is a preparation to use the online_type as an array index.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-3-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand 956f8b4450 drivers/base/memory: rename MMOP_ONLINE_KEEP to MMOP_ONLINE
Patch series "mm/memory_hotplug: allow to specify a default online_type", v3.

Distributions nowadays use udev rules ([1] [2]) to specify if and how to
online hotplugged memory.  The rules seem to get more complex with many
special cases.  Due to the various special cases,
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE cannot be used.  All memory hotplug
is handled via udev rules.

Every time we hotplug memory, the udev rule will come to the same
conclusion.  Especially Hyper-V (but also soon virtio-mem) add a lot of
memory in separate memory blocks and wait for memory to get onlined by
user space before continuing to add more memory blocks (to not add memory
faster than it is getting onlined).  This of course slows down the whole
memory hotplug process.

To make the job of distributions easier and to avoid udev rules that get
more and more complicated, let's extend the mechanism provided by
- /sys/devices/system/memory/auto_online_blocks
- "memhp_default_state=" on the kernel cmdline
to be able to specify also "online_movable" as well as "online_kernel"

=== Example /usr/libexec/config-memhotplug ===

#!/bin/bash

VIRT=`systemd-detect-virt --vm`
ARCH=`uname -p`

sense_virtio_mem() {
  if [ -d "/sys/bus/virtio/drivers/virtio_mem/" ]; then
    DEVICES=`find /sys/bus/virtio/drivers/virtio_mem/ -maxdepth 1 -type l | wc -l`
    if [ $DEVICES != "0" ]; then
        return 0
    fi
  fi
  return 1
}

if [ ! -e "/sys/devices/system/memory/auto_online_blocks" ]; then
  echo "Memory hotplug configuration support missing in the kernel"
  exit 1
fi

if grep "memhp_default_state=" /proc/cmdline > /dev/null; then
  echo "Memory hotplug configuration overridden in kernel cmdline (memhp_default_state=)"
  exit 1
fi

if [ $VIRT == "microsoft" ]; then
  echo "Detected Hyper-V on $ARCH"
  # Hyper-V wants all memory in ZONE_NORMAL
  ONLINE_TYPE="online_kernel"
elif sense_virtio_mem; then
  echo "Detected virtio-mem on $ARCH"
  # virtio-mem wants all memory in ZONE_NORMAL
  ONLINE_TYPE="online_kernel"
elif [ $ARCH == "s390x" ] || [ $ARCH == "s390" ]; then
  echo "Detected $ARCH"
  # standby memory should not be onlined automatically
  ONLINE_TYPE="offline"
elif [ $ARCH == "ppc64" ] || [ $ARCH == "ppc64le" ]; then
  echo "Detected" $ARCH
  # PPC64 onlines all hotplugged memory right from the kernel
  ONLINE_TYPE="offline"
elif [ $VIRT == "none" ]; then
  echo "Detected bare-metal on $ARCH"
  # Bare metal users expect hotplugged memory to be unpluggable. We assume
  # that ZONE imbalances on such enterpise servers cannot happen and is
  # properly documented
  ONLINE_TYPE="online_movable"
else
  # TODO: Hypervisors that want to unplug DIMMs and can guarantee that ZONE
  # imbalances won't happen
  echo "Detected $VIRT on $ARCH"
  # Usually, ballooning is used in virtual environments, so memory should go to
  # ZONE_NORMAL. However, sometimes "movable_node" is relevant.
  ONLINE_TYPE="online"
fi

echo "Selected online_type:" $ONLINE_TYPE

# Configure what to do with memory that will be hotplugged in the future
echo $ONLINE_TYPE 2>/dev/null > /sys/devices/system/memory/auto_online_blocks
if [ $? != "0" ]; then
  echo "Memory hotplug cannot be configured (e.g., old kernel or missing permissions)"
  # A backup udev rule should handle old kernels if necessary
  exit 1
fi

# Process all already pluggedd blocks (e.g., DIMMs, but also Hyper-V or virtio-mem)
if [ $ONLINE_TYPE != "offline" ]; then
  for MEMORY in /sys/devices/system/memory/memory*; do
    STATE=`cat $MEMORY/state`
    if [ $STATE == "offline" ]; then
        echo $ONLINE_TYPE > $MEMORY/state
    fi
  done
fi

=== Example /usr/lib/systemd/system/config-memhotplug.service ===

[Unit]
Description=Configure memory hotplug behavior
DefaultDependencies=no
Conflicts=shutdown.target
Before=sysinit.target shutdown.target
After=systemd-modules-load.service
ConditionPathExists=|/sys/devices/system/memory/auto_online_blocks

[Service]
ExecStart=/usr/libexec/config-memhotplug
Type=oneshot
TimeoutSec=0
RemainAfterExit=yes

[Install]
WantedBy=sysinit.target

=== Example modification to the 40-redhat.rules [2] ===

: diff --git a/40-redhat.rules b/40-redhat.rules-new
: index 2c690e5..168fd03 100644
: --- a/40-redhat.rules
: +++ b/40-redhat.rules-new
: @@ -6,6 +6,9 @@ SUBSYSTEM=="cpu", ACTION=="add", TEST=="online", ATTR{online}=="0", ATTR{online}
:  # Memory hotadd request
:  SUBSYSTEM!="memory", GOTO="memory_hotplug_end"
:  ACTION!="add", GOTO="memory_hotplug_end"
: +# memory hotplug behavior configured
: +PROGRAM=="grep online /sys/devices/system/memory/auto_online_blocks", GOTO="memory_hotplug_end"
: +
:  PROGRAM="/bin/uname -p", RESULT=="s390*", GOTO="memory_hotplug_end"
:
:  ENV{.state}="online"

===

[1] https://github.com/lnykryn/systemd-rhel/pull/281
[2] https://github.com/lnykryn/systemd-rhel/blob/staging/rules/40-redhat.rules

This patch (of 8):

The name is misleading and it's not really clear what is "kept".  Let's
just name it like the online_type name we expose to user space ("online").

Add some documentation to the types.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Yumei Huang <yuhuang@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Link: http://lkml.kernel.org/r/20200319131221.14044-1-david@redhat.com
Link: http://lkml.kernel.org/r/20200317104942.11178-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand fada9ae3ed drivers/base/memory.c: drop pages_correctly_probed()
pages_correctly_probed() is a leftover from ancient times.  It dates back
to commit 3947be1969 ("[PATCH] memory hotplug: sysfs and add/remove
functions"), where Pg_reserved checks were added as a sfety net:

	/*
	 * The probe routines leave the pages reserved, just
	 * as the bootmem code does.  Make sure they're still
	 * that way.
	 */

The checks were refactored quite a bit over the years, especially in
commit b77eab7079 ("mm/memory_hotplug: optimize probe routine"), where
checks for present, valid, and online sections were added.

Hotplugged memory is added via add_memory(), which will create the full
memmap for the hotplugged memory, and mark all sections valid and present.

Only full memory blocks are onlined/offlined, so we also cannot have an
inconsistency in that regard (especially, memory blocks with some sections
being online and some being offline).

1. Boot memory always starts online.  Since commit c5e79ef561
   ("mm/memory_hotplug.c: don't allow to online/offline memory blocks with
   holes") we disallow to offline any memory with holes.  Therefore, we
   never online memory with holes.  Present and validity checks are
   superfluous.

2. Only complete memory blocks are onlined/offlined (and especially,
   the state - online or offline - is stored for whole memory blocks).
   Besides the core, only arch/powerpc/platforms/powernv/memtrace.c
   manually calls offline_pages() and fiddels with memory block states.
   But it also only offlines complete memory blocks.

3. To make any of these conditions trigger, something would have to be
   terribly messed up in the core.  (e.g., online/offline only some
   sections of a memory block).

4. Memory unplug properly makes sure that all sysfs attributes were
   removed (and therefore, that all threads left the sysfs handlers).  We
   don't have to worry about zombie devices at this point.

5. The valid_section_nr(section_nr) check is actually dead code, as it
   would never have been reached due to the WARN_ON_ONCE(!pfn_valid(pfn)).

No wonder we haven't seen any of these errors in a long time (or even
   ever, according to my search).  Let's just get rid of them.  Now, all
   checks that could hinder onlining and offlining are completely
   contained in online_pages()/offline_pages().

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Link: http://lkml.kernel.org/r/20200127110424.5757-3-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand 68c3a6ac65 drivers/base/memory.c: drop section_count
Patch series "mm: drop superfluous section checks when onlining/offlining".

Let's drop some superfluous section checks on the onlining/offlining path.

This patch (of 3):

Since commit c5e79ef561 ("mm/memory_hotplug.c: don't allow to
online/offline memory blocks with holes") we have a generic check in
offline_pages() that disallows offlining memory blocks with holes.

Memory blocks with missing sections are just another variant of these type
of blocks.  We can stop checking (and especially storing) present
sections.  A proper error message is now printed why offlining failed.

section_count was initially introduced in commit 0768121597 ("Driver
core: Add section count to memory_block struct") in order to detect when
it is okay to remove a memory block.  It was used in commit 26bbe7ef6d
("drivers/base/memory.c: prohibit offlining of memory blocks with missing
sections") to disallow offlining memory blocks with missing sections.  As
we refactored creation/removal of memory devices and have a proper check
for holes in place, we can drop the section_count.

This also removes a leftover comment regarding the mem_sysfs_mutex, which
was removed in commit 848e19ad3c ("drivers/base/memory.c: drop the
mem_sysfs_mutex").

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Link: http://lkml.kernel.org/r/20200127110424.5757-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:40 -07:00
David Hildenbrand 53cdc1cb29 drivers/base/memory.c: indicate all memory blocks as removable
We see multiple issues with the implementation/interface to compute
whether a memory block can be offlined (exposed via
/sys/devices/system/memory/memoryX/removable) and would like to simplify
it (remove the implementation).

1. It runs basically lockless. While this might be good for performance,
   we see possible races with memory offlining that will require at
   least some sort of locking to fix.

2. Nowadays, more false positives are possible. No arch-specific checks
   are performed that validate if memory offlining will not be denied
   right away (and such check will require locking). For example, arm64
   won't allow to offline any memory block that was added during boot -
   which will imply a very high error rate. Other archs have other
   constraints.

3. The interface is inherently racy. E.g., if a memory block is detected
   to be removable (and was not a false positive at that time), there is
   still no guarantee that offlining will actually succeed. So any
   caller already has to deal with false positives.

4. It is unclear which performance benefit this interface actually
   provides. The introducing commit 5c755e9fd8 ("memory-hotplug: add
   sysfs removable attribute for hotplug memory remove") mentioned

	"A user-level agent must be able to identify which sections
	 of memory are likely to be removable before attempting the
	 potentially expensive operation."

   However, no actual performance comparison was included.

Known users:

 - lsmem: Will group memory blocks based on the "removable" property. [1]

 - chmem: Indirect user. It has a RANGE mode where one can specify
          removable ranges identified via lsmem to be offlined. However,
          it also has a "SIZE" mode, which allows a sysadmin to skip the
          manual "identify removable blocks" step. [2]

 - powerpc-utils: Uses the "removable" attribute to skip some memory
          blocks right away when trying to find some to offline+remove.
          However, with ballooning enabled, it already skips this
          information completely (because it once resulted in many false
          negatives). Therefore, the implementation can deal with false
          positives properly already. [3]

According to Nathan Fontenot, DLPAR on powerpc is nowadays no longer
driven from userspace via the drmgr command (powerpc-utils).  Nowadays
it's managed in the kernel - including onlining/offlining of memory
blocks - triggered by drmgr writing to /sys/kernel/dlpar.  So the
affected legacy userspace handling is only active on old kernels.  Only
very old versions of drmgr on a new kernel (unlikely) might execute
slower - totally acceptable.

With CONFIG_MEMORY_HOTREMOVE, always indicating "removable" should not
break any user space tool.  We implement a very bad heuristic now.
Without CONFIG_MEMORY_HOTREMOVE we cannot offline anything, so report
"not removable" as before.

Original discussion can be found in [4] ("[PATCH RFC v1] mm:
is_mem_section_removable() overhaul").

Other users of is_mem_section_removable() will be removed next, so that
we can remove is_mem_section_removable() completely.

[1] http://man7.org/linux/man-pages/man1/lsmem.1.html
[2] http://man7.org/linux/man-pages/man8/chmem.8.html
[3] https://github.com/ibm-power-utilities/powerpc-utils
[4] https://lkml.kernel.org/r/20200117105759.27905-1-david@redhat.com

Also, this patch probably fixes a crash reported by Steve.
http://lkml.kernel.org/r/CAPcyv4jpdaNvJ67SkjyUJLBnBnXXQv686BiVW042g03FUmWLXw@mail.gmail.com

Reported-by: "Scargall, Steve" <steve.scargall@intel.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Nathan Fontenot <ndfont@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200128093542.6908-1-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-03-29 09:47:05 -07:00
David Hildenbrand 9291799884 mm/memory_hotplug: drop valid_start/valid_end from test_pages_in_a_zone()
The callers are only interested in the actual zone, they don't care about
boundaries.  Return the zone instead to simplify.

Link: http://lkml.kernel.org/r/20200110183308.11849-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-04 03:05:23 +00:00
David Hildenbrand bd5c2344f9 mm/memory_hotplug: pass in nid to online_pages()
Patch series "mm/memory_hotplug: pass in nid to online_pages()".

Simplify onlining code and get rid of find_memory_block().  Pass in the
nid from the memory block we are trying to online directly, instead of
manually looking it up.

This patch (of 2):

No need to lookup the memory block, we can directly pass in the nid.

Link: http://lkml.kernel.org/r/20200113113354.6341-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-01-31 10:30:39 -08:00
David Hildenbrand 3f9903b9ca mm: remove the memory isolate notifier
Luckily, we have no users left, so we can get rid of it.  Cleanup
set_migratetype_isolate() a little bit.

Link: http://lkml.kernel.org/r/20191114131911.11783-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Qian Cai <cai@lca.pw>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-01-31 10:30:38 -08:00
David Hildenbrand 848e19ad3c drivers/base/memory.c: drop the mem_sysfs_mutex
The mem_sysfs_mutex isn't really helpful.  Also, it's not really clear
what the mutex protects at all.

The device lists of the memory subsystem are protected separately.  We
don't need that mutex when looking up.  creating, or removing
independent devices.  find_memory_block_by_id() will perform locking on
its own and grab a reference of the returned device.

At the time memory_dev_init() is called, we cannot have concurrent
hot(un)plug operations yet - we're still fairly early during boot.  We
don't need any locking.

The creation/removal of memory block devices should be protected on a
higher level - especially using the device hotplug lock to avoid
documented issues (see Documentation/core-api/memory-hotplug.rst) - or
if that is reworked, using similar locking.

Protecting in the context of these functions only doesn't really make
sense.  Especially, if we would have a situation where the same memory
blocks are created/deleted at the same time, there is something horribly
going wrong (imagining adding/removing a DIMM at the same time from two
call paths) - after the functions succeeded something else in the
callers would blow up (e.g., create_memory_block_devices() succeeded but
there are no memory block devices anymore).

All relevant call paths (except when adding memory early during boot via
ACPI, which is now documented) hold the device hotplug lock when adding
memory, and when removing memory.  Let's document that instead.

Add a simple safety net to create_memory_block_devices() in case we
would actually remove memory blocks while adding them, so we'll never
dereference a NULL pointer.  Simplify memory_dev_init() now that the
lock is gone.

Link: http://lkml.kernel.org/r/20190925082621.4927-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-01 12:59:04 -08:00
Naoya Horiguchi feec24a613 mm, soft-offline: convert parameter to pfn
Currently soft_offline_page() receives struct page, and its sibling
memory_failure() receives pfn.  This discrepancy looks weird and makes
precheck on pfn validity tricky.  So let's align them.

Link: http://lkml.kernel.org/r/20191016234706.GA5493@www9186uo.sakura.ne.jp
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-01 12:59:04 -08:00
David Hildenbrand 2c91f8fc6c mm/memory_hotplug: fix try_offline_node()
try_offline_node() is pretty much broken right now:

 - The node span is updated when onlining memory, not when adding it. We
   ignore memory that was mever onlined. Bad.

 - We touch possible garbage memmaps. The pfn_to_nid(pfn) can easily
   trigger a kernel panic. Bad for memory that is offline but also bad
   for subsection hotadd with ZONE_DEVICE, whereby the memmap of the
   first PFN of a section might contain garbage.

 - Sections belonging to mixed nodes are not properly considered.

As memory blocks might belong to multiple nodes, we would have to walk
all pageblocks (or at least subsections) within present sections.
However, we don't have a way to identify whether a memmap that is not
online was initialized (relevant for ZONE_DEVICE).  This makes things
more complicated.

Luckily, we can piggy pack on the node span and the nid stored in memory
blocks.  Currently, the node span is grown when calling
move_pfn_range_to_zone() - e.g., when onlining memory, and shrunk when
removing memory, before calling try_offline_node().  Sysfs links are
created via link_mem_sections(), e.g., during boot or when adding
memory.

If the node still spans memory or if any memory block belongs to the
nid, we don't set the node offline.  As memory blocks that span multiple
nodes cannot get offlined, the nid stored in memory blocks is reliable
enough (for such online memory blocks, the node still spans the memory).

Introduce for_each_memory_block() to efficiently walk all memory blocks.

Note: We will soon stop shrinking the ZONE_DEVICE zone and the node span
when removing ZONE_DEVICE memory to fix similar issues (access of
garbage memmaps) - until we have a reliable way to identify whether
these memmaps were properly initialized.  This implies later, that once
a node had ZONE_DEVICE memory, we won't be able to set a node offline -
which should be acceptable.

Since commit f1dd2cd13c ("mm, memory_hotplug: do not associate
hotadded memory to zones until online") memory that is added is not
assoziated with a zone/node (memmap not initialized).  The introducing
commit 60a5a19e74 ("memory-hotplug: remove sysfs file of node")
already missed that we could have multiple nodes for a section and that
the zone/node span is updated when onlining pages, not when adding them.

I tested this by hotplugging two DIMMs to a memory-less and cpu-less
NUMA node.  The node is properly onlined when adding the DIMMs.  When
removing the DIMMs, the node is properly offlined.

Masayoshi Mizuma reported:

: Without this patch, memory hotplug fails as panic:
:
:  BUG: kernel NULL pointer dereference, address: 0000000000000000
:  ...
:  Call Trace:
:   remove_memory_block_devices+0x81/0xc0
:   try_remove_memory+0xb4/0x130
:   __remove_memory+0xa/0x20
:   acpi_memory_device_remove+0x84/0x100
:   acpi_bus_trim+0x57/0x90
:   acpi_bus_trim+0x2e/0x90
:   acpi_device_hotplug+0x2b2/0x4d0
:   acpi_hotplug_work_fn+0x1a/0x30
:   process_one_work+0x171/0x380
:   worker_thread+0x49/0x3f0
:   kthread+0xf8/0x130
:   ret_from_fork+0x35/0x40

[david@redhat.com: v3]
  Link: http://lkml.kernel.org/r/20191102120221.7553-1-david@redhat.com
Link: http://lkml.kernel.org/r/20191028105458.28320-1-david@redhat.com
Fixes: 60a5a19e74 ("memory-hotplug: remove sysfs file of node")
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visiable after d0dc12e86b
Signed-off-by: David Hildenbrand <david@redhat.com>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-11-15 18:34:00 -08:00
David Hildenbrand 641fe2e938 drivers/base/memory.c: don't access uninitialized memmaps in soft_offline_page_store()
Uninitialized memmaps contain garbage and in the worst case trigger kernel
BUGs, especially with CONFIG_PAGE_POISONING.  They should not get touched.

Right now, when trying to soft-offline a PFN that resides on a memory
block that was never onlined, one gets a misleading error with
CONFIG_PAGE_POISONING:

  :/# echo 5637144576 > /sys/devices/system/memory/soft_offline_page
  [   23.097167] soft offline: 0x150000 page already poisoned

But the actual result depends on the garbage in the memmap.

soft_offline_page() can only work with online pages, it returns -EIO in
case of ZONE_DEVICE.  Make sure to only forward pages that are online
(iow, managed by the buddy) and, therefore, have an initialized memmap.

Add a check against pfn_to_online_page() and similarly return -EIO.

Link: http://lkml.kernel.org/r/20191010141200.8985-1-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[visible after d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-10-19 06:32:31 -04:00
David Hildenbrand b6c88d3b9d drivers/base/memory.c: don't store end_section_nr in memory blocks
Each memory block spans the same amount of sections/pages/bytes.  The size
is determined before the first memory block is created.  No need to store
what we can easily calculate - and the calculations even look simpler now.

Michal brought up the idea of variable-sized memory blocks.  However, if
we ever implement something like this, we will need an API compatibility
switch and reworks at various places (most code assumes a fixed memory
block size).  So let's cleanup what we have right now.

While at it, fix the variable naming in register_mem_sect_under_node() -
we no longer talk about a single section.

Link: http://lkml.kernel.org/r/20190809110200.2746-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24 15:54:09 -07:00
David Hildenbrand 902ce63b33 driver/base/memory.c: validate memory block size early
Let's validate the memory block size early, when initializing the memory
device infrastructure.  Fail hard in case the value is not suitable.

As nobody checks the return value of memory_dev_init(), turn it into a
void function and fail with a panic in all scenarios instead.  Otherwise,
we'll crash later during boot when core/drivers expect that the memory
device infrastructure (including memory_block_size_bytes()) works as
expected.

I think long term, we should move the whole memory block size
configuration (set_memory_block_size_order() and
memory_block_size_bytes()) into drivers/base/memory.c.

Link: http://lkml.kernel.org/r/20190806090142.22709-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24 15:54:09 -07:00
David Hildenbrand f915fb7fb2 drivers/base/memory.c: fixup documentation of removable/phys_index/block_size_bytes
Let's rephrase to memory block terminology and add some further
clarifications.

Link: http://lkml.kernel.org/r/20190806080826.5963-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24 15:54:09 -07:00
David Hildenbrand d84f2f5a75 drivers/base/node.c: simplify unregister_memory_block_under_nodes()
We don't allow to offline memory block devices that belong to multiple
numa nodes.  Therefore, such devices can never get removed.  It is
sufficient to process a single node when removing the memory block.  No
need to iterate over each and every PFN.

We already have the nid stored for each memory block.  Make sure that the
nid always has a sane value.

Please note that checking for node_online(nid) is not required.  If we
would have a memory block belonging to a node that is no longer offline,
then we would have a BUG in the node offlining code.

Link: http://lkml.kernel.org/r/20190719135244.15242-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24 15:54:09 -07:00
David Hildenbrand dd62528591 drivers/base/memory.c: get rid of find_memory_block_hinted()
No longer needed, let's remove it.  Also, drop the "hint" parameter
completely from "find_memory_block_by_id", as nobody needs it anymore.

[david@redhat.com: v3]
  Link: http://lkml.kernel.org/r/20190620183139.4352-7-david@redhat.com
[david@redhat.com: handle zero-length walks]
  Link: http://lkml.kernel.org/r/1c2edc22-afd7-2211-c4c7-40e54e5007e8@redhat.com
Link: http://lkml.kernel.org/r/20190614100114.311-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Qian Cai <cai@lca.pw>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:07 -07:00
David Hildenbrand ea8846411a mm/memory_hotplug: move and simplify walk_memory_blocks()
Let's move walk_memory_blocks() to the place where memory block logic
resides and simplify it.  While at it, add a type for the callback
function.

Link: http://lkml.kernel.org/r/20190614100114.311-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand 90ec010fe0 drivers/base/memory: use "unsigned long" for block ids
Block ids are just shifted section numbers, so let's also use "unsigned
long" for them, too.

Link: http://lkml.kernel.org/r/20190614100114.311-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand 2491f0a2c0 mm: section numbers use the type "unsigned long"
Patch series "mm: Further memory block device cleanups", v1.

Some further cleanups around memory block devices.  Especially, clean up
and simplify walk_memory_range().  Including some other minor cleanups.

This patch (of 6):

We are using a mixture of "int" and "unsigned long".  Let's make this
consistent by using "unsigned long" everywhere.  We'll do the same with
memory block ids next.

While at it, turn the "unsigned long i" in removable_show() into an int
- sections_per_block is an int.

[akpm@linux-foundation.org: s/unsigned long i/unsigned long nr/]
[david@redhat.com: v3]
  Link: http://lkml.kernel.org/r/20190620183139.4352-2-david@redhat.com
Link: http://lkml.kernel.org/r/20190614100114.311-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand 4c4b7f9ba9 mm/memory_hotplug: remove memory block devices before arch_remove_memory()
Let's factor out removing of memory block devices, which is only
necessary for memory added via add_memory() and friends that created
memory block devices.  Remove the devices before calling
arch_remove_memory().

This finishes factoring out memory block device handling from
arch_add_memory() and arch_remove_memory().

Link: http://lkml.kernel.org/r/20190527111152.16324-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand db051a0dac mm/memory_hotplug: create memory block devices after arch_add_memory()
Only memory to be added to the buddy and to be onlined/offlined by user
space using /sys/devices/system/memory/...  needs (and should have!)
memory block devices.

Factor out creation of memory block devices.  Create all devices after
arch_add_memory() succeeded.  We can later drop the want_memblock
parameter, because it is now effectively stale.

Only after memory block devices have been added, memory can be onlined
by user space.  This implies, that memory is not visible to user space
at all before arch_add_memory() succeeded.

While at it
 - use WARN_ON_ONCE instead of BUG_ON in moved unregister_memory()
 - introduce find_memory_block_by_id() to search via block id
 - Use find_memory_block_by_id() in init_memory_block() to catch
   duplicates

Link: http://lkml.kernel.org/r/20190527111152.16324-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand 80ec922dbd mm/memory_hotplug: allow arch_remove_memory() without CONFIG_MEMORY_HOTREMOVE
We want to improve error handling while adding memory by allowing to use
arch_remove_memory() and __remove_pages() even if
CONFIG_MEMORY_HOTREMOVE is not set to e.g., implement something like:

	arch_add_memory()
	rc = do_something();
	if (rc) {
		arch_remove_memory();
	}

We won't get rid of CONFIG_MEMORY_HOTREMOVE for now, as it will require
quite some dependencies for memory offlining.

Link: http://lkml.kernel.org/r/20190527111152.16324-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand 1811582587 drivers/base/memory: pass a block_id to init_memory_block()
We'll rework hotplug_memory_register() shortly, so it no longer consumes
pass a section.

[cai@lca.pw: fix a compilation warning]
  Link: http://lkml.kernel.org/r/1559320186-28337-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/20190527111152.16324-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:06 -07:00
David Hildenbrand cb7b3a3685 mm/memory_hotplug: make unregister_memory_section() never fail
Failing while removing memory is mostly ignored and cannot really be
handled.  Let's treat errors in unregister_memory_section() in a nice way,
warning, but continuing.

Link: http://lkml.kernel.org/r/20190409100148.24703-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 09:47:49 -07:00
Baoquan He 063b8a4cee drivers/base/memory.c: clean up relics in function parameters
The input parameter 'phys_index' of memory_block_action() is actually the
section number, but not the phys_index of memory_block.  This is a relic
from the past when one memory block could only contain one section.
Rename it to start_section_nr.

And also in remove_memory_section(), the 'node_id' and 'phys_device'
arguments are not used by anyone.  Remove them.

Link: http://lkml.kernel.org/r/20190329144250.14315-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 09:47:48 -07:00
zhong jiang 37803841c9 mm/memory_hotplug: do not unlock after failing to take the device_hotplug_lock
When adding memory by probing a memory block in the sysfs interface,
there is an obvious issue where we will unlock the device_hotplug_lock
when we failed to takes it.

That issue was introduced in 8df1d0e4a2 ("mm/memory_hotplug: make
add_memory() take the device_hotplug_lock").

We should drop out in time when failing to take the device_hotplug_lock.

Link: http://lkml.kernel.org/r/1554696437-9593-1-git-send-email-zhongjiang@huawei.com
Fixes: 8df1d0e4a2 ("mm/memory_hotplug: make add_memory() take the device_hotplug_lock")
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reported-by: Yang yingliang <yangyingliang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-04-19 09:46:04 -07:00
Dave Hansen c221c0b030 device-dax: "Hotplug" persistent memory for use like normal RAM
This is intended for use with NVDIMMs that are physically persistent
(physically like flash) so that they can be used as a cost-effective
RAM replacement.  Intel Optane DC persistent memory is one
implementation of this kind of NVDIMM.

Currently, a persistent memory region is "owned" by a device driver,
either the "Direct DAX" or "Filesystem DAX" drivers.  These drivers
allow applications to explicitly use persistent memory, generally
by being modified to use special, new libraries. (DIMM-based
persistent memory hardware/software is described in great detail
here: Documentation/nvdimm/nvdimm.txt).

However, this limits persistent memory use to applications which
*have* been modified.  To make it more broadly usable, this driver
"hotplugs" memory into the kernel, to be managed and used just like
normal RAM would be.

To make this work, management software must remove the device from
being controlled by the "Device DAX" infrastructure:

	echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind

and then tell the new driver that it can bind to the device:

	echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id

After this, there will be a number of new memory sections visible
in sysfs that can be onlined, or that may get onlined by existing
udev-initiated memory hotplug rules.

This rebinding procedure is currently a one-way trip.  Once memory
is bound to "kmem", it's there permanently and can not be
unbound and assigned back to device_dax.

The kmem driver will never bind to a dax device unless the device
is *explicitly* bound to the driver.  There are two reasons for
this: One, since it is a one-way trip, it can not be undone if
bound incorrectly.  Two, the kmem driver destroys data on the
device.  Think of if you had good data on a pmem device.  It
would be catastrophic if you compile-in "kmem", but leave out
the "device_dax" driver.  kmem would take over the device and
write volatile data all over your good data.

This inherits any existing NUMA information for the newly-added
memory from the persistent memory device that came from the
firmware.  On Intel platforms, the firmware has guarantees that
require each socket's persistent memory to be in a separate
memory-only NUMA node.  That means that this patch is not expected
to create NUMA nodes, but will simply hotplug memory into existing
nodes.

Because NUMA nodes are created, the existing NUMA APIs and tools
are sufficient to create policies for applications or memory areas
to have affinity for or an aversion to using this memory.

There is currently some metadata at the beginning of pmem regions.
The section-size memory hotplug restrictions, plus this small
reserved area can cause the "loss" of a section or two of capacity.
This should be fixable in follow-on patches.  But, as a first step,
losing 256MB of memory (worst case) out of hundreds of gigabytes
is a good tradeoff vs. the required code to fix this up precisely.
This calculation is also the reason we export
memory_block_size_bytes().

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-28 10:41:23 -08:00
Linus Torvalds b07039b79c Driver core patches for 4.21-rc1
Here is the "big" set of driver core patches for 4.21-rc1.
 
 It's not really big, just a number of small changes for some reported
 issues, some documentation updates to hopefully make it harder for
 people to abuse the driver model, and some other minor cleanups.
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 -----BEGIN PGP SIGNATURE-----
 
 iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCXCY/dA8cZ3JlZ0Brcm9h
 aC5jb20ACgkQMUfUDdst+ylZrgCeIi+rWj0mqlyKZk0A+gurH2BPmfwAniGfiHJp
 w60Fr5/EbCqUr1d1wQIO
 =4N7R
 -----END PGP SIGNATURE-----

Merge tag 'driver-core-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the "big" set of driver core patches for 4.21-rc1.

  It's not really big, just a number of small changes for some reported
  issues, some documentation updates to hopefully make it harder for
  people to abuse the driver model, and some other minor cleanups.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  mm, memory_hotplug: update a comment in unregister_memory()
  component: convert to DEFINE_SHOW_ATTRIBUTE
  sysfs: Disable lockdep for driver bind/unbind files
  driver core: Add missing dev->bus->need_parent_lock checks
  kobject: return error code if writing /sys/.../uevent fails
  driver core: Move async_synchronize_full call
  driver core: platform: Respect return code of platform_device_register_full()
  kref/kobject: Improve documentation
  drivers/base/memory.c: Use DEVICE_ATTR_RO and friends
  driver core: Replace simple_strto{l,ul} by kstrtou{l,ul}
  kernfs: Improve kernfs_notify() poll notification latency
  kobject: Fix warnings in lib/kobject_uevent.c
  kobject: drop unnecessary cast "%llu" for u64
  driver core: fix comments for device_block_probing()
  driver core: Replace simple_strtol by kstrtoint
2018-12-28 20:44:29 -08:00
Michal Hocko 1ecc07fd0a memory_hotplug: add missing newlines to debugging output
pages_correctly_probed is missing new lines which means that the line is
not printed rightaway but it rather waits for additional printks.

Add \n to all three messages in pages_correctly_probed.

Link: http://lkml.kernel.org/r/20181218162307.10518-1-mhocko@kernel.org
Fixes: b77eab7079 ("mm/memory_hotplug: optimize probe routine")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:51 -08:00
Wei Yang 3b6fd6ffb2 drivers/base/memory.c: remove an unnecessary check on NR_MEM_SECTIONS
In cb5e39b803 ("drivers: base: refactor add_memory_section() to
add_memory_block()"), add_memory_block() is introduced, which is only
invoked in memory_dev_init().

When combining these two loops in memory_dev_init() and
add_memory_block(), they looks like this:

    for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block)
        for (j = i;
	    (j < i + sections_per_block) && j < NR_MEM_SECTIONS;
	    j++)

Since it is sure the (i < NR_MEM_SECTIONS) and j sits in its own memory
block, the check of (j < NR_MEM_SECTIONS) is not necessary.

This patch just removes this check.

Link: http://lkml.kernel.org/r/20181123222811.18216-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Seth Jennings <sjenning@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:48 -08:00
Dan Carpenter 16df1456aa mm, memory_hotplug: update a comment in unregister_memory()
The remove_memory_block() function was renamed to in commit
cc292b0b43 ("drivers/base/memory.c: rename remove_memory_block() to
remove_memory_section()").

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-20 16:33:18 +01:00
David Hildenbrand 3f8e917853 drivers/base/memory.c: Use DEVICE_ATTR_RO and friends
Let's use the easier to read (and not mess up) variants:
- Use DEVICE_ATTR_RO
- Use DEVICE_ATTR_WO
- Use DEVICE_ATTR_RW
instead of the more generic DEVICE_ATTR() we're using right now.

We have to rename most callback functions. By fixing the intendations we
can even save some LOCs.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-06 13:54:14 +01:00
David Hildenbrand 381eab4a6e mm/memory_hotplug: fix online/offline_pages called w.o. mem_hotplug_lock
There seem to be some problems as result of 30467e0b3b ("mm, hotplug:
fix concurrent memory hot-add deadlock"), which tried to fix a possible
lock inversion reported and discussed in [1] due to the two locks
	a) device_lock()
	b) mem_hotplug_lock

While add_memory() first takes b), followed by a) during
bus_probe_device(), onlining of memory from user space first took a),
followed by b), exposing a possible deadlock.

In [1], and it was decided to not make use of device_hotplug_lock, but
rather to enforce a locking order.

The problems I spotted related to this:

1. Memory block device attributes: While .state first calls
   mem_hotplug_begin() and the calls device_online() - which takes
   device_lock() - .online does no longer call mem_hotplug_begin(), so
   effectively calls online_pages() without mem_hotplug_lock.

2. device_online() should be called under device_hotplug_lock, however
   onlining memory during add_memory() does not take care of that.

In addition, I think there is also something wrong about the locking in

3. arch/powerpc/platforms/powernv/memtrace.c calls offline_pages()
   without locks. This was introduced after 30467e0b3b. And skimming over
   the code, I assume it could need some more care in regards to locking
   (e.g. device_online() called without device_hotplug_lock. This will
   be addressed in the following patches.

Now that we hold the device_hotplug_lock when
- adding memory (e.g. via add_memory()/add_memory_resource())
- removing memory (e.g. via remove_memory())
- device_online()/device_offline()

We can move mem_hotplug_lock usage back into
online_pages()/offline_pages().

Why is mem_hotplug_lock still needed? Essentially to make
get_online_mems()/put_online_mems() be very fast (relying on
device_hotplug_lock would be very slow), and to serialize against
addition of memory that does not create memory block devices (hmm).

[1] http://driverdev.linuxdriverproject.org/pipermail/ driverdev-devel/
    2015-February/065324.html

This patch is partly based on a patch by Vitaly Kuznetsov.

Link: http://lkml.kernel.org/r/20180925091457.28651-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 08:54:17 -07:00
David Hildenbrand 8df1d0e4a2 mm/memory_hotplug: make add_memory() take the device_hotplug_lock
add_memory() currently does not take the device_hotplug_lock, however
is aleady called under the lock from
	arch/powerpc/platforms/pseries/hotplug-memory.c
	drivers/acpi/acpi_memhotplug.c
to synchronize against CPU hot-remove and similar.

In general, we should hold the device_hotplug_lock when adding memory to
synchronize against online/offline request (e.g.  from user space) - which
already resulted in lock inversions due to device_lock() and
mem_hotplug_lock - see 30467e0b3b ("mm, hotplug: fix concurrent memory
hot-add deadlock").  add_memory()/add_memory_resource() will create memory
block devices, so this really feels like the right thing to do.

Holding the device_hotplug_lock makes sure that a memory block device
can really only be accessed (e.g. via .online/.state) from user space,
once the memory has been fully added to the system.

The lock is not held yet in
	drivers/xen/balloon.c
	arch/powerpc/platforms/powernv/memtrace.c
	drivers/s390/char/sclp_cmd.c
	drivers/hv/hv_balloon.c
So, let's either use the locked variants or take the lock.

Don't export add_memory_resource(), as it once was exported to be used by
XEN, which is never built as a module.  If somebody requires it, we also
have to export a locked variant (as device_hotplug_lock is never
exported).

Link: http://lkml.kernel.org/r/20180925091457.28651-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-31 08:54:17 -07:00
Mikhail Zaslonko 4e8346d0be memory_hotplug: fix kernel_panic on offline page processing
Within show_valid_zones() the function test_pages_in_a_zone() should be
called for online memory blocks only.

Otherwise it might lead to the VM_BUG_ON due to uninitialized struct
pages (when CONFIG_DEBUG_VM_PGFLAGS kernel option is set):

 page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
 ------------[ cut here ]------------
 Call Trace:
 ([<000000000038f91e>] test_pages_in_a_zone+0xe6/0x168)
  [<0000000000923472>] show_valid_zones+0x5a/0x1a8
  [<0000000000900284>] dev_attr_show+0x3c/0x78
  [<000000000046f6f0>] sysfs_kf_seq_show+0xd0/0x150
  [<00000000003ef662>] seq_read+0x212/0x4b8
  [<00000000003bf202>] __vfs_read+0x3a/0x178
  [<00000000003bf3ca>] vfs_read+0x8a/0x148
  [<00000000003bfa3a>] ksys_read+0x62/0xb8
  [<0000000000bc2220>] system_call+0xdc/0x2d8

That VM_BUG_ON was triggered by the page poisoning introduced in
mm/sparse.c with the git commit d0dc12e86b ("mm/memory_hotplug:
optimize memory hotplug").

With the same commit the new 'nid' field has been added to the struct
memory_block in order to store and later on derive the node id for
offline pages (instead of accessing struct page which might be
uninitialized).  But one reference to nid in show_valid_zones() function
has been overlooked.  Fixed with current commit.  Also, nr_pages will
not be used any more after test_pages_in_a_zone() call, do not update
it.

Link: http://lkml.kernel.org/r/20180828090539.41491-1-zaslonko@linux.ibm.com
Fixes: d0dc12e86b ("mm/memory_hotplug: optimize memory hotplug")
Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: <stable@vger.kernel.org>	[4.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-09-04 16:45:02 -07:00