My group ran into a AIO process hang on a 2.6.24 kernel with the process
sleeping indefinitely in io_getevents(2) waiting for the last wakeup to come
and it never would.
We ran the tests on x86_64 SMP. The hang only occurred on a Xeon box
("Clovertown") but not a Core2Duo ("Conroe"). On the Xeon, the L2 cache isn't
shared between all eight processors, but is L2 is shared between between all
two processors on the Core2Duo we use.
My analysis of the hang is if you go down to the second while-loop
in read_events(), what happens on processor #1:
1) add_wait_queue_exclusive() adds thread to ctx->wait
2) aio_read_evt() to check tail
3) if aio_read_evt() returned 0, call [io_]schedule() and sleep
In aio_complete() with processor #2:
A) info->tail = tail;
B) waitqueue_active(&ctx->wait)
C) if waitqueue_active() returned non-0, call wake_up()
The way the code is written, step 1 must be seen by all other processors
before processor 1 checks for pending events in step 2 (that were recorded by
step A) and step A by processor 2 must be seen by all other processors
(checked in step 2) before step B is done.
The race I believed I was seeing is that steps 1 and 2 were
effectively swapped due to the __list_add() being delayed by the L2
cache not shared by some of the other processors. Imagine:
proc 2: just before step A
proc 1, step 1: adds to ctx->wait, but is not visible by other processors yet
proc 1, step 2: checks tail and sees no pending events
proc 2, step A: updates tail
proc 1, step 3: calls [io_]schedule() and sleeps
proc 2, step B: checks ctx->wait, but sees no one waiting, skips wakeup
so proc 1 sleeps indefinitely
My patch adds a memory barrier between steps A and B. It ensures that the
update in step 1 gets seen on processor 2 before continuing. If processor 1
was just before step 1, the memory barrier makes sure that step A (update
tail) gets seen by the time processor 1 makes it to step 2 (check tail).
Before the patch our AIO process would hang virtually 100% of the time. After
the patch, we have yet to see the process ever hang.
Signed-off-by: Quentin Barnes <qbarnes+linux@yahoo-inc.com>
Reviewed-by: Zach Brown <zach.brown@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: <stable@kernel.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ We should probably disallow that "if (waitqueue_active()) wake_up()"
coding pattern, because it's so often buggy wrt memory ordering ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx:
async_tx: avoid the async xor_zero_sum path when src_cnt > device->max_xor
fsldma: Fix the DMA halt when using DMA_INTERRUPT async_tx transfer.
This reverts commit 2c81ce4c9c.
It caused several new troubles (eg suspend slowdown bisected down to
this patch by Pavel Machek), so just revert it for now.
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Cc: Pavel Machek <pavel@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we handle all the special commands using REQ_TYPE_ATA_TASKFILE
rather than using the old REQ_TYPE_ATA_CMD model, we need to also
emulate the lack of full taskfile data that comes with the old command
model (ie when commands are generated with the HDIO_DRIVE_CMD ioctl
rather than using the HDIO_DRIVE_TASK[FILE] ioctls).
In particular, this means that we should handle command completion the
more relaxed way that the old drive_cmd_intr() code did. It allows
commands to finish early even if they don't use up all the data that we
thought we had for them.
This fixes a regression seen by Anders Eriksson where some SMART
commands sent by smartd would cause a boot-time system hang on his
machine because the IDE command handling code didn't realize that the
command had completed.
Tested-by: Anders Eriksson <aeriksson@fastmail.fm>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
WAKE_IDLE is too agressive on multi-core CPUs with the new
wake-affine code, keep it on for SMT/HT balancing alone
(where there's no cache affinity at all between logical CPUs).
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Wakeup-buddy tasks are cache-hot - this makes it a bit harder
for the load-balancer to tear them apart. (but it's still possible,
if the load is sufficiently assymetric)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
improve affine wakeups. Maintain the 'overlap' metric based on CFS's
sum_exec_runtime - which means the amount of time a task executes
after it wakes up some other task.
Use the 'overlap' for the wakeup decisions: if the 'overlap' is short,
it means there's strong workload coupling between this task and the
woken up task. If the 'overlap' is large then the workload is decoupled
and the scheduler will move them to separate CPUs more easily.
( Also slightly move the preempt_check within try_to_wake_up() - this has
no effect on functionality but allows 'early wakeups' (for still-on-rq
tasks) to be correctly accounted as well.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
'sync' wakeups are a hint towards the scheduler that (certain)
networking related wakeups likely create coupling between tasks.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
split out the affine-wakeup bits.
No code changed:
kernel/sched.o:
text data bss dec hex filename
42521 2858 232 45611 b22b sched.o.before
42521 2858 232 45611 b22b sched.o.after
md5:
9d76738f1272aa82f0b7affd2f51df6b sched.o.before.asm
09b31c44e9aff8666f72773dc433e2df sched.o.after.asm
(the md5's changed because stack slots changed and some registers
get scheduled by gcc in a different order - but otherwise the before
and after assembly is instruction for instruction equivalent.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If the channel cannot perform the operation in one call to
->device_prep_dma_zero_sum, then fallback to the xor+page_is_zero path.
This only affects users with arrays larger than 16 devices on iop13xx or
32 devices on iop3xx.
Cc: <stable@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The DMA_INTERRUPT async_tx is a NULL transfer, thus the BCR(count register)
is 0. When the transfer started with a byte count of zero, the DMA
controller will triger a PE(programming error) event and halt, not a normal
interrupt. I add special codes for PE event and DMA_INTERRUPT
async_tx testing.
Signed-off-by: Zhang Wei <wei.zhang@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
HID: update key codes for Apple aluminium
HID: fix comment in hid_input_report()
HID: BADPAD entry for NATSU Playstation USB adapter
HID: Use DIV_ROUND_UP
HID: remove HID_QUIRK_APPLE_ISO_KEYBOARD for 4th generation macbook
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
Revert "unexport bio_{,un}map_user"
relay: fix subbuf_splice_actor() adding too many pages
The ps2esdi driver was marked as BROKEN more than two years ago due to being
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/ati_pcigart: fix the PCIGART to use drm_pci to allocate GART table.
drm/radeon: fixup RV550 chip family
drm/via: attempt again to stabilise the AGP DMA command submission.
drm: Fix race that can lockup the kernel
F5 and F6 have no second function printed on them. Thus their definitions have
been removed from the table.
KEY_CYCLEWINDOWS doesn't name the function of Mac OS X' Expose properly and
because we couldn't find a better key code, we decided to use KEY_FN_F4
instead.
We also changed KEY_BACK and KEY_FORWARD, which apply to browser functions, to
KEY_PREVIOUSSONG and KEY_NEXTSONG, since the keys are intended to control a
music player.
Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The hid_input_report() in debug mode of course outputs the report itself, not
the device report descriptor.
Fix this error in comment.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Add quirk entry for BADPAD for the NATSU Playstation USB adapter. The
adapter is supported under Linux, but with bad direction detection.
Signed-off-by: Andrew Burton <adb@iinet.net.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
(d)) but is perhaps more readable.
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
begin_undock() is only called when triggered via a acpi notify handler
(pressing the undock button on the dock station), but complete_undock() is
always called after the eject. So if a undock is triggered through a sysfs
write, the flag DOCK_UNDOCKING has to be set for the dock station,
too. Otherwise this will freeze the system hard.
Signed-off-by: Holger Macht <hmacht@suse.de>
Acked-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
led_out is boolean, so there is no functional change here,
but apparently an extra mask with 1 caused some style checkers
to flag this as logic bug.
Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
The generic thermal I/F gets selected by ACPI_THERMAL --
its only current customer.
it doesn't need to clutter other configs by default.
Signed-off-by: Len Brown <len.brown@intel.com>
From: Zhang Rui <rui.zhang@intel.com>
(reverting the previous sysfs patch also reverted a fix
to the thermal units documentation, which is restored by this commit)
The generic thermal driver shows temperature in millidegree Celsius.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This reverts commit 3152fb9f11.
This broke libsensors.
Acked-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Len Brown <len.brown@intel.com>
Secondary input device did not have parent set up causing it
to appear in the root of sysfs device hierarchy.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
drivers/ata/libata-acpi.c fails to build
drivers/built-in.o: In function `ata_acpi_associate':
(.text+0x7106a): undefined reference to `register_hotplug_dock_device'
When CONFIG_ATA_ACPI=y and CONFIG_ACPI_DOCK=m
But if dock is selected from ata_acpi, dock will =y
when ata_acpi=y, avoiding this problem.
http://bugzilla.kernel.org/show_bug.cgi?id=10272
Signed-off-by: Len Brown <len.brown@intel.com>
Acer BIOS has a bug which is exposed when a dead battery is present.
The package template that is used to describe battery status is
over-written with sane values when the battery is live.
But when the batter is dead, a bogus reference in the template
is used. In this case, Linux returns a fault, when instead
it should simply return that it doesn't know the missing value.
http://bugzilla.kernel.org/show_bug.cgi?id=8573http://bugzilla.kernel.org/show_bug.cgi?id=10202
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
This fixes a 2.6.25 regression reported by Alex Chiang.
Invoke pciehp_enable_slot() at startup only when pciehp_force=1.
Some HP equipment apparently cannot cope with it otherwise.
This restores the (previously working) 2.6.24 behaviour here,
while allowing machines that need a kick to use pciehp_force=1.
This was the original design back in October 2007,
but Kristen suggested we try without it first:
Kristen Carlson Accardi wrote:
>I think it would be ok to try allowing the slot to be enabled when not
>using pciehp_force mode. We can wrap it later if it proves to break things
This ended up breaking one of Alex's setups,
so it's time to put the wrapper back in now.
Signed-off-by: Mark Lord <mlord@pobox.com>
Acked-by: Alex Chiang <achiang@hp.com>
Acked-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch makes the needlessly global selinux_parse_opts_str() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
Outside users like asmlib uses the mapping functions. API wise, the
export is definitely sane. It's a better idea to keep this export
than to require external users to open-code this piece of code instead.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
The fallback path needs to enable interrupts like done for
the other page allocator calls. This was not necessary with
the alternate fast path since we handled irq enable/disable in
the slow path. The regular fastpath handles irq enable/disable
around calls to the slow path so we need to restore the proper
status before calling the page allocator from the slowpath.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
ahci: Add Marvell 6121 SATA support
pata_ali: use atapi_cmd_type() to determine cmd type instead of transfer size
ahci: implement skip_host_reset parameter
ahci: request all PCI BARs
devres: implement pcim_iomap_regions_request_all()
libata-acpi: improve dock event handling
oops and fs corruption; the latter can happen even on valid fs in case of oom.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Quentin Barnes