With ppc64 we use the deposited pgtable_t to store the hash pte slot
information. We should not withdraw the deposited pgtable_t without
marking the pmd none. This ensure that low level hash fault handling
will skip this huge pte and we will handle them at upper levels.
Recent change to pmd splitting changed the above in order to handle the
race between pmd split and exit_mmap. The race is explained below.
Consider following race:
CPU0 CPU1
shrink_page_list()
add_to_swap()
split_huge_page_to_list()
__split_huge_pmd_locked()
pmdp_huge_clear_flush_notify()
// pmd_none() == true
exit_mmap()
unmap_vmas()
zap_pmd_range()
// no action on pmd since pmd_none() == true
pmd_populate()
As result the THP will not be freed. The leak is detected by check_mm():
BUG: Bad rss-counter state mm:ffff880058d2e580 idx:1 val:512
The above required us to not mark pmd none during a pmd split.
The fix for ppc is to clear the huge pte of _PAGE_USER, so that low
level fault handling code skip this pte. At higher level we do take ptl
lock. That should serialze us against the pmd split. Once the lock is
acquired we do check the pmd again using pmd_same. That should always
return false for us and hence we should retry the access. We do the
pmd_same check in all case after taking plt with
THP (do_huge_pmd_wp_page, do_huge_pmd_numa_page and
huge_pmd_set_accessed)
Also make sure we wait for irq disable section in other cpus to finish
before flipping a huge pte entry with a regular pmd entry. Code paths
like find_linux_pte_or_hugepte depend on irq disable to get
a stable pte_t pointer. A parallel thp split need to make sure we
don't convert a pmd pte to a regular pmd entry without waiting for the
irq disable section to finish.
Fixes: eef1b3ba05 ("thp: implement split_huge_pmd()")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This was wrongly updated by commit 7aa9a23c69 ("powerpc, thp: remove
infrastructure for handling splitting PMDs") during the last merge
window. Fix it up.
This could lead to incorrect behaviour in THP and/or mprotect(), at a
minimum.
Fixes: 7aa9a23c69 ("powerpc, thp: remove infrastructure for handling splitting PMDs")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Commit d5d6a443b2 ("arch/powerpc/include/asm/pgtable-ppc64.h:
add pmd_[dirty|mkclean] for THP") added a new identical definition
of pmd_dirty(). Remove it again.
Cc: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
MADV_FREE needs pmd_dirty and pmd_mkclean for detecting recent overwrite
of the contents since MADV_FREE syscall is called for THP page.
This patch adds pmd_dirty and pmd_mkclean for THP page MADV_FREE
support.
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Shaohua Li <shli@kernel.org>
Cc: <yalin.wang2010@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jason Evans <je@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttil <mika.penttila@nextfour.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Roland Dreier <roland@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Shaohua Li <shli@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With new refcounting we don't need to mark PMDs splitting. Let's drop
code to handle this.
pmdp_splitting_flush() is not needed too: on splitting PMD we will do
pmdp_clear_flush() + set_pte_at(). pmdp_clear_flush() will do IPI as
needed for fast_gup.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Swapoff after swapping hangs on the G5, when CONFIG_CHECKPOINT_RESTORE=y
but CONFIG_MEM_SOFT_DIRTY is not set. That's because the non-zero
_PAGE_SWP_SOFT_DIRTY bit, added by CONFIG_HAVE_ARCH_SOFT_DIRTY=y, is not
discounted when CONFIG_MEM_SOFT_DIRTY is not set: so swap ptes cannot be
recognized.
(I suspect that the peculiar dependence of HAVE_ARCH_SOFT_DIRTY on
CHECKPOINT_RESTORE in arch/powerpc/Kconfig comes from an incomplete
attempt to solve this problem.)
It's true that the relationship between CONFIG_HAVE_ARCH_SOFT_DIRTY and
and CONFIG_MEM_SOFT_DIRTY is too confusing, and it's true that swapoff
should be made more robust; but nevertheless, fix up the powerpc ifdefs
as x86_64 and s390 (which met the same problem) have them, defining the
bits as 0 if CONFIG_MEM_SOFT_DIRTY is not set.
Fixes: 7207f43665 ("powerpc/mm: Add page soft dirty tracking")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Core kernel expects swp_entry_t to consist of only swap type and swap
offset. We should not leak pte bits into swp_entry_t. This breaks
swapoff which use the swap type and offset to build a swp_entry_t and
later compare that to the swp_entry_t obtained from linux page table
pte. Leaking pte bits into swp_entry_t breaks that comparison and
results in us looping in try_to_unuse.
The stack trace can be anywhere below try_to_unuse() in mm/swapfile.c,
since swapoff is circling around and around that function, reading from
each used swap block into a page, then trying to find where that page
belongs, looking at every non-file pte of every mm that ever swapped.
Fixes: 6a119eae94 ("powerpc/mm: Add a _PAGE_PTE bit")
Reported-by: Hugh Dickins <hughd@google.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
User space checkpoint and restart tool (CRIU) needs the page's change
to be soft tracked. This allows to do a pre checkpoint and then dump
only touched pages.
This is done by using a newly assigned PTE bit (_PAGE_SOFT_DIRTY) when
the page is backed in memory, and a new _PAGE_SWP_SOFT_DIRTY bit when
the page is swapped out.
To introduce a new PTE _PAGE_SOFT_DIRTY bit value common to hash 4k
and hash 64k pte, the bits already defined in hash-*4k.h should be
shifted left by one.
The _PAGE_SWP_SOFT_DIRTY bit is dynamically put after the swap type in
the swap pte. A check is added to ensure that the bit is not
overwritten by _PAGE_HPTEFLAGS.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Use the #define instead of open-coding the same
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
pte and pmd table size are dependent on config items. Don't
hard code the same. This make sure we use the right value
when masking pmd entries and also while checking pmd_bad
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
For a pte entry we will have _PAGE_PTE set. Our pte page
address have a minimum alignment requirement of HUGEPD_SHIFT_MASK + 1.
We use the lower 7 bits to indicate hugepd. ie.
For pmd and pgd we can find:
1) _PAGE_PTE set pte -> indicate PTE
2) bits [2..6] non zero -> indicate hugepd.
They also encode the size. We skip bit 1 (_PAGE_PRESENT).
3) othewise pointer to next table.
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We support THP only with book3s_64 and 64K page size. Move
THP details to hash64-64k.h to clarify the same.
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
W.r.t hugetlb, we support two format for pmd. With book3s_64 and
64K linux page size, we can have pte at the pmd level. Hence we
don't need to support hugepd there. For everything else hugepd
is supported and pmd_huge is (0).
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Instead of open coding it in multiple code paths, export the helper
and add more documentation. Also make sure we don't make assumption
regarding pte bit position
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Convert from asm to C
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
No real change, only style changes
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This free up 11 bits in pte_t. In the later patch we also change
the pte_t format so that we can start supporting migration pte
at pmd level. We now track 4k subpage valid bit as below
If we have _PAGE_COMBO set, we override the _PAGE_F_GIX_SHIFT
and _PAGE_F_SECOND. Together we have 4 bits, each of them
used to indicate whether any of the 4 4k subpage in that group
is valid. ie,
[ group 1 bit ] [ group 2 bit ] ..... [ group 4 ]
[ subpage 1 - 4] [ subpage 5- 8] ..... [ subpage 13 - 16]
We still track each 4k subpage slot number and secondary hash
information in the second half of pgtable_t. Removing the subpage
tracking have some significant overhead on aim9 and ebizzy benchmark and
to support THP with 4K subpage, we do need a pgtable_t of 4096 bytes.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
functions which operate on pte bits are moved to hash*.h and other
generic functions are moved to pgtable.h
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This enables us to keep hash64 related bits together, and makes it easy
to follow.
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We convert them static inline function here as we did with pte_val in
the previous patch
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We also convert few #define to static inline in this patch for better
type checking
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We copy only needed PTE bits define from pte-common.h to respective
hash related header. This should greatly simply later patches in which
we are going to change the pte format for hash config
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We are going to drop pte_common.h in the later patch. The idea is to
enable hash code not require to define all PTE bits. Having PTE bits
defined in pte_common.h made the code unnecessarily complex.
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We also move __ASSEMBLY__ towards the end of header. This avoid
having #ifndef __ASSEMBLY___ all over the header
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This further make a copy of pte defines to book3s/64/hash*.h. This
remove the dependency on pgtable-ppc64-4k.h and pgtable-ppc64-64k.h
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In this patch we do:
cp pgtable-ppc32.h book3s/32/pgtable.h
cp pgtable-ppc64.h book3s/64/pgtable.h
This enable us to do further changes to hash specific config.
We will change the page table format for 64bit hash in later patches.
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Paul Mackerras