While testing CPU DLPAR, the following problem was discovered.
We were DLPAR removing the first CPU, which in this case was
logical CPUs 0-3. CPUs 0-2 were already marked offline and
we were in the process of offlining CPU 3. After marking
the CPU inactive and offline in cpu_disable, but before the
cpu was completely idle (cpu_die), we ended up in __make_request
on CPU 3. There we looked at the topology map to see which CPU
to complete the I/O on and found no CPUs in the cpu_sibling_map.
This resulted in the block layer setting the completion cpu
to be NR_CPUS, which then caused an oops when we tried to
complete the I/O.
Fix this by sanity checking the value we return from blk_cpu_to_group
to be a valid cpu value.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
When alloc fails, free_table is being called. Depending on the number of
bytes requested, we determine if we are going to call _get_free_page()
or kmalloc(). When alloc fails, our math is wrong (due to sg_size - 1),
and the last buffer is wrongfully assumed to have been allocated by
kmalloc. Hence, kfree gets called and a panic occurs.
Signed-off-by: Jeffrey Carlyle <jeff.carlyle@motorola.com>
Signed-off-by: Olusanya Soyannwo <c23746@motorola.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Setting the task state here may cause us to miss the wake up from
kthread_stop(), so we need to recheck kthread_should_stop() or risk
sleeping forever in the following schedule().
Symptom was an indefinite hang on an NFSv4 mount. (NFSv4 may create
multiple mounts in a temporary namespace while traversing the mount
path, and since the temporary namespace is immediately destroyed, it may
end up destroying a mount very soon after it was created, possibly
making this race more likely.)
INFO: task mount.nfs4:4314 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
mount.nfs4 D 0000000000000000 2880 4314 4313 0x00000000
ffff88001ed6da28 0000000000000046 ffff88001ed6dfd8 ffff88001ed6dfd8
ffff88001ed6c000 ffff88001ed6c000 ffff88001ed6c000 ffff88001e5003a0
ffff88001ed6dfd8 ffff88001e5003a8 ffff88001ed6c000 ffff88001ed6dfd8
Call Trace:
[<ffffffff8196090d>] schedule_timeout+0x1cd/0x2e0
[<ffffffff8106a31c>] ? mark_held_locks+0x6c/0xa0
[<ffffffff819639a0>] ? _raw_spin_unlock_irq+0x30/0x60
[<ffffffff8106a5fd>] ? trace_hardirqs_on_caller+0x14d/0x190
[<ffffffff819671fe>] ? sub_preempt_count+0xe/0xd0
[<ffffffff8195fc80>] wait_for_common+0x120/0x190
[<ffffffff81033c70>] ? default_wake_function+0x0/0x20
[<ffffffff8195fdcd>] wait_for_completion+0x1d/0x20
[<ffffffff810595fa>] kthread_stop+0x4a/0x150
[<ffffffff81061a60>] ? thaw_process+0x70/0x80
[<ffffffff810cc68a>] bdi_unregister+0x10a/0x1a0
[<ffffffff81229dc9>] nfs_put_super+0x19/0x20
[<ffffffff810ee8c4>] generic_shutdown_super+0x54/0xe0
[<ffffffff810ee9b6>] kill_anon_super+0x16/0x60
[<ffffffff8122d3b9>] nfs4_kill_super+0x39/0x90
[<ffffffff810eda45>] deactivate_locked_super+0x45/0x60
[<ffffffff810edfb9>] deactivate_super+0x49/0x70
[<ffffffff81108294>] mntput_no_expire+0x84/0xe0
[<ffffffff811084ef>] release_mounts+0x9f/0xc0
[<ffffffff81108575>] put_mnt_ns+0x65/0x80
[<ffffffff8122cc56>] nfs_follow_remote_path+0x1e6/0x420
[<ffffffff8122cfbf>] nfs4_try_mount+0x6f/0xd0
[<ffffffff8122d0c2>] nfs4_get_sb+0xa2/0x360
[<ffffffff810edcb8>] vfs_kern_mount+0x88/0x1f0
[<ffffffff810ede92>] do_kern_mount+0x52/0x130
[<ffffffff81963d9a>] ? _lock_kernel+0x6a/0x170
[<ffffffff81108e9e>] do_mount+0x26e/0x7f0
[<ffffffff81106b3a>] ? copy_mount_options+0xea/0x190
[<ffffffff811094b8>] sys_mount+0x98/0xf0
[<ffffffff810024d8>] system_call_fastpath+0x16/0x1b
1 lock held by mount.nfs4/4314:
#0: (&type->s_umount_key#24){+.+...}, at: [<ffffffff810edfb1>] deactivate_super+0x41/0x70
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This patch fixes the following issue:
INFO: task mount.nfs4:1120 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
mount.nfs4 D 00000000fffc6a21 0 1120 1119 0x00000000
ffff880235643948 0000000000000046 ffffffff00000000 ffffffff00000000
ffff880235643fd8 ffff880235314760 00000000001d44c0 ffff880235643fd8
00000000001d44c0 00000000001d44c0 00000000001d44c0 00000000001d44c0
Call Trace:
[<ffffffff813bc747>] schedule_timeout+0x34/0xf1
[<ffffffff813bc530>] ? wait_for_common+0x3f/0x130
[<ffffffff8106b50b>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff813bc5c3>] wait_for_common+0xd2/0x130
[<ffffffff8104159c>] ? default_wake_function+0x0/0xf
[<ffffffff813beaa0>] ? _raw_spin_unlock+0x26/0x2a
[<ffffffff813bc6bb>] wait_for_completion+0x18/0x1a
[<ffffffff81101a03>] sync_inodes_sb+0xca/0x1bc
[<ffffffff811056a6>] __sync_filesystem+0x47/0x7e
[<ffffffff81105798>] sync_filesystem+0x47/0x4b
[<ffffffff810e7ffd>] generic_shutdown_super+0x22/0xd2
[<ffffffff810e80f8>] kill_anon_super+0x11/0x4f
[<ffffffffa00d06d7>] nfs4_kill_super+0x3f/0x72 [nfs]
[<ffffffff810e7b68>] deactivate_locked_super+0x21/0x41
[<ffffffff810e7fd6>] deactivate_super+0x40/0x45
[<ffffffff810fc66c>] mntput_no_expire+0xb8/0xed
[<ffffffff810fc73b>] release_mounts+0x9a/0xb0
[<ffffffff810fc7bb>] put_mnt_ns+0x6a/0x7b
[<ffffffffa00d0fb2>] nfs_follow_remote_path+0x19a/0x296 [nfs]
[<ffffffffa00d11ca>] nfs4_try_mount+0x75/0xaf [nfs]
[<ffffffffa00d1790>] nfs4_get_sb+0x276/0x2ff [nfs]
[<ffffffff810e7dba>] vfs_kern_mount+0xb8/0x196
[<ffffffff810e7ef6>] do_kern_mount+0x48/0xe8
[<ffffffff810fdf68>] do_mount+0x771/0x7e8
[<ffffffff810fe062>] sys_mount+0x83/0xbd
[<ffffffff810089c2>] system_call_fastpath+0x16/0x1b
The reason of this hang was a race condition: when the flusher thread is
forking a bdi thread, we use 'kthread_run()', so we run it _before_ we make it
visible in 'bdi->wb.task'. The bdi thread runs, does all works, and goes sleep.
'bdi->wb.task' is still NULL. And this is a dangerous time window.
If at this time someone queues a work for this bdi, he does not see the bdi
thread and wakes up the forker thread instead! But the forker has already
forked this bdi thread, but just did not make it visible yet!
The result is that we lose the wake up event for this bdi thread and the NFS4
code waits forever.
To fix the problem, we should use 'ktrhead_create()' for creating bdi threads,
then make them visible in 'bdi->wb.task', and only after this wake them up.
This is exactly what this patch does.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The ioctl path and the scsi tape path were not accounting
for their additions to the queue depth.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Now that we have this API, switch the two in-kernel users to it.
Resolves an oops introduced by commit
1abec4fdbb.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Currently drivers must do an elevator_exit() + elevator_init()
to switch IO schedulers. There are a few problems with this:
- Since commit 1abec4fdbb,
elevator_init() requires a zeroed out q->elevator
pointer. The two existing in-kernel users don't do that.
- It will only work at initialization time, since using the
above two-staged construct does not properly quisce the queue.
So add elevator_change() which takes care of this, and convert
the elv_iosched_store() sysfs interface to use this helper as well.
Reported-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reported-by: Kevin Vigor <kevin@vigor.nu>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The kmalloc() in bio_integrity_prep() is failable, so remove __GFP_NOFAIL
from its mask.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Return of the bi_rw tests is no longer bool after commit 74450be1. But
results of such tests are stored in bools. This doesn't fit in there
for some compilers (gcc 4.5 here), so either use !! magic to get real
bools or use ulong where the result is assigned somewhere.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
If kmalloc() fails then cleanup and return failure (-1).
Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Some documentation to provide help with tunables.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Divyesh had gotten rid of this code in the past. I want to re-introduce it
back as it helps me a lot during debugging.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Divyesh Shah <dpshah@google.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Implement a new tunable group_idle, which allows idling on the group
instead of a cfq queue. Hence one can set slice_idle = 0 and not idle
on the individual queues but idle on the group. This way on fast storage
we can get fairness between groups at the same time overall throughput
improves.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Implement another CFQ mode where we charge group in terms of number
of requests dispatched instead of measuring the time. Measuring in terms
of time is not possible when we are driving deeper queue depths and there
are requests from multiple cfq queues in the request queue.
o This mode currently gets activated if one sets slice_idle=0 and associated
disk supports NCQ. Again the idea is that on an NCQ disk with idling disabled
most of the queues will dispatch 1 or more requests and then cfq queue
expiry happens and we don't have a way to measure time. So start providing
fairness in terms of IOPS.
o Currently IOPS mode works only with cfq group scheduling. CFQ is following
different scheduling algorithms for queue and group scheduling. These IOPS
stats are used only for group scheduling hence in non-croup mode nothing
should change.
o For CFQ group scheduling one can disable slice idling so that we don't idle
on queue and drive deeper request queue depths (achieving better throughput),
at the same time group idle is enabled so one should get service
differentiation among groups.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Do not idle either on cfq queue or service tree if slice_idle=0. User does
not want any queue or service tree idling. Currently even if slice_idle=0,
we were waiting for request to finish before expiring the queue and that
can lead to lower queue depths.
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The doorbell reset initially appears to work correctly,
the controller resets, comes up, some i/o can even be
done, but on at least some Smart Arrays in some servers,
it eventually causes a subsequent controller lockup due
to some kind of PCIe error, and kdump can end up leaving
the root filesystem in an unbootable state. For this
reason, until the problem is fixed, or at least isolated
to certain hardware enough to be avoided, the doorbell
reset should not be used at all.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
If the cgroup hierarchy for blkio control groups is deeper than two
levels, kernel should not allow the creation of further levels. mkdir
system call does not except EINVAL as a return value. This patch
replaces EINVAL with more appropriate EPERM
Signed-off-by: Ciju Rajan K <ciju@linux.vnet.ibm.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* 'radix-tree' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev:
radix-tree: radix_tree_range_tag_if_tagged() can set incorrect tags
radix-tree: clear all tags in radix_tree_node_rcu_free
Commit ebf8aa44be ("radix-tree:
omplement function radix_tree_range_tag_if_tagged") does not safely
set tags on on intermediate tree nodes. The code walks down the tree
setting tags before it has fully resolved the path to the leaf under
the assumption there will be a leaf slot with the tag set in the
range it is searching.
Unfortunately, this is not a valid assumption - we can abort after
setting a tag on an intermediate node if we overrun the number of
tags we are allowed to set in a batch, or stop scanning because we
we have passed the last scan index before we reach a leaf slot with
the tag we are searching for set.
As a result, we can leave the function with tags set on intemediate
nodes which can be tripped over later by tag-based lookups. The
result of these stale tags is that lookup may end prematurely or
livelock because the lookup cannot make progress.
The fix for the problem involves reocrding the traversal path we
take to the leaf nodes, and only propagating the tags back up the
tree once the tag is set in the leaf node slot. We are already
recording the path for efficient traversal, so there is no
additional overhead to do the intermediately node tag setting in
this manner.
This fixes a radix tree lookup livelock triggered by the new
writeback sync livelock avoidance code introduced in commit
f446daaea9 ("mm: implement writeback
livelock avoidance using page tagging").
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Acked-by: Jan Kara <jack@suse.cz>
Commit f446daaea9 ("mm: implement
writeback livelock avoidance using page tagging") introduced a new
radix tree tag, increasing the number of tags in each node from 2 to
3. It did not, however, fix up the code in
radix_tree_node_rcu_free() that cleans up after radix_tree_shrink()
and hence could leave stray tags set in the new tag array.
The result is that the livelock avoidance code added in the the
above commit would hit stale tags when doing tag based lookups,
resulting in livelocks when trying to traverse the tree.
Fix this problem in radix_tree_node_rcu_free() so it doesn't happen
again in the future by using a loop to walk all the tags up to
RADIX_TREE_MAX_TAGS to clear the stray tags radix_tree_shrink()
leaves behind.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Acked-by: Nick Piggin <npiggin@kernel.dk>
Acked-by: Jan Kara <jack@suse.cz>
* 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: PIT: free irq source id in handling error path
KVM: destroy workqueue on kvm_create_pit() failures
KVM: fix poison overwritten caused by using wrong xstate size
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt/drm-intel: (58 commits)
drm/i915,intel_agp: Add support for Sandybridge D0
drm/i915: fix render pipe control notify on sandybridge
agp/intel: set 40-bit dma mask on Sandybridge
drm/i915: Remove the conflicting BUG_ON()
drm/i915/suspend: s/IS_IRONLAKE/HAS_PCH_SPLIT/
drm/i915/suspend: Flush register writes before busy-waiting.
i915: disable DAC on Ironlake also when doing CRT load detection.
drm/i915: wait for actual vblank, not just 20ms
drm/i915: make sure eDP PLL is enabled at the right time
drm/i915: fix VGA plane disable for Ironlake+
drm/i915: eDP mode set sequence corrections
drm/i915: add panel reset workaround
drm/i915: Enable RC6 on Ironlake.
drm/i915/sdvo: Only set is_lvds if we have a valid fixed mode.
drm/i915: Set up a render context on Ironlake
drm/i915 invalidate indirect state pointers at end of ring exec
drm/i915: Wake-up wait_request() from elapsed hang-check (v2)
drm/i915: Apply i830 errata for cursor alignment
drm/i915: Only update i845/i865 CURBASE when disabled (v2)
drm/i915: FBC is updated within set_base() so remove second call in mode_set()
...
This one is missed in last pipe control fix for sandybridge,
that really unmask interrupt bit for notify in render engine IMR.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
We now attempt to free "active" objects following a GPU hang as either
the GPU will be reset or the hang is permenant. In either case, the GPU
writes will not be flushed to main memory and it should be safe to
return that memory back to the system.
The BUG_ON(active) is thus overkill and can erroneously fire after a
EIO.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
For the shared paths on the next generation chipsets.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
Like on Sandybridge, disabling the DAC here when doing CRT load detect
avoids forever hangs waiting on the hardware.
test procedure on HP 2740p:
boot with no VGA plugged in, start X,
plug in VGA monitor (1280x1024)
chvt 3
machine hangs waiting forever.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Waiting for a hard coded 20ms isn't always enough to make sure a vblank
period has actually occurred, so add code to make sure we really have
passed through a vblank period (or that the pipe is off when disabling).
This prevents problems with mode setting and link training, and seems to
fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
on an HP 8440p instead. Hopefully also fixes
https://bugs.freedesktop.org/show_bug.cgi?id=29141.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
With the introduction of the new unified work queue thread pools,
we lost one feature: It's no longer possible to know which worker
is causing the CPU to wake out of idle. The result is that PowerTOP
now reports a lot of "kworker/a:b" instead of more readable results.
This patch adds a pair of tracepoints to the new workqueue code,
similar in style to the timer/hrtimer tracepoints.
With this pair of tracepoints, the next PowerTOP can correctly
report which work item caused the wakeup (and how long it took):
Interrupt (43) i915 time 3.51ms wakeups 141
Work ieee80211_iface_work time 0.81ms wakeups 29
Work do_dbs_timer time 0.55ms wakeups 24
Process Xorg time 21.36ms wakeups 4
Timer sched_rt_period_timer time 0.01ms wakeups 1
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "Configure" word tends to make user believe they have to say 'yes'
to be able to choose the number of procs/nodes. "Enable" should be
unambiguous enough.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Like the mlock() change previously, this makes the stack guard check
code use vma->vm_prev to see what the mapping below the current stack
is, rather than have to look it up with find_vma().
Also, accept an abutting stack segment, since that happens naturally if
you split the stack with mlock or mprotect.
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we've split the stack vma, only the lowest one has the guard page.
Now that we have a doubly linked list of vma's, checking this is trivial.
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's a really simple list, and several of the users want to go backwards
in it to find the previous vma. So rather than have to look up the
previous entry with 'find_vma_prev()' or something similar, just make it
doubly linked instead.
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Apparently, the check for a 6-byte ID string introduced by commit
426c457a32 ("mtd: nand: extend NAND flash
detection to new MLC chips") is NOT sufficient to determine whether or
not a Samsung chip uses their new MLC detection scheme or the old,
standard scheme. This adds a condition to check cell type.
Signed-off-by: Tilman Sauerbeck <tilman@code-monkey.de>
Signed-off-by: Brian Norris <norris@broadcom.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org
This list moved to lists.ozlabs.org quite some time ago.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All these lists moved to lists.ozlabs.org quite a while ago.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Chapter 6 is right about mutex_trylock, but chapter 10 wasn't. This error
was introduced during semaphore-to-mutex conversion of the Unreliable
guide. :-)
If user context which performs mutex_lock() or mutex_trylock() is
preempted by interrupt context which performs mutex_trylock() on the same
mutex instance, a deadlock occurs. This is because these functions do not
disable local IRQs when they operate on mutex->wait_lock.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gcc-4.0.2:
drivers/scsi/qla4xxx/ql4_os.c: In function 'qla4_8xxx_error_recovery':
drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
drivers/scsi/qla4xxx/ql4_os.c:2377: sorry, unimplemented: called from here
drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
drivers/scsi/qla4xxx/ql4_os.c:2393: sorry, unimplemented: called from here
Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dump_tasks() needs to hold the RCU read lock around its access of the
target task's UID. To this end it should use task_uid() as it only needs
that one thing from the creds.
The fact that dump_tasks() holds tasklist_lock is insufficient to prevent the
target process replacing its credentials on another CPU.
Then, this patch change to call rcu_read_lock() explicitly.
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
mm/oom_kill.c:410 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
4 locks held by kworker/1:2/651:
#0: (events){+.+.+.}, at: [<ffffffff8106aae7>]
process_one_work+0x137/0x4a0
#1: (moom_work){+.+...}, at: [<ffffffff8106aae7>]
process_one_work+0x137/0x4a0
#2: (tasklist_lock){.+.+..}, at: [<ffffffff810fafd4>]
out_of_memory+0x164/0x3f0
#3: (&(&p->alloc_lock)->rlock){+.+...}, at: [<ffffffff810fa48e>]
find_lock_task_mm+0x2e/0x70
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 0aad4b3124 ("oom: fold __out_of_memory into out_of_memory")
introduced a tasklist_lock leak. Then it caused following obvious
danger warnings and panic.
================================================
[ BUG: lock held when returning to user space! ]
------------------------------------------------
rsyslogd/1422 is leaving the kernel with locks still held!
1 lock held by rsyslogd/1422:
#0: (tasklist_lock){.+.+.+}, at: [<ffffffff810faf64>] out_of_memory+0x164/0x3f0
BUG: scheduling while atomic: rsyslogd/1422/0x00000002
INFO: lockdep is turned off.
This patch fixes it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
