linux-stable.git/mm/backing-dev.c, branch v3.16.75

block: fix bdi vs gendisk lifetime mismatch

2016-11-20T01:17:05+00:00

commit df08c32ce3be5be138c1dbfcba203314a3a7cd6f upstream.

The name for a bdi of a gendisk is derived from the gendisk's devt.
However, since the gendisk is destroyed before the bdi it leaves a
window where a new gendisk could dynamically reuse the same devt while a
bdi with the same name is still live.  Arrange for the bdi to hold a
reference against its "owner" disk device while it is registered.
Otherwise we can hit sysfs duplicate name collisions like the following:

 WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80
 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1'

 Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015
  0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec
  ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351
  0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8
 Call Trace:
  [] dump_stack+0x63/0x87
  [] __warn+0xd1/0xf0
  [] warn_slowpath_fmt+0x5f/0x80
  [] sysfs_warn_dup+0x64/0x80
  [] sysfs_create_dir_ns+0x7e/0x90
  [] kobject_add_internal+0xaa/0x320
  [] ? vsnprintf+0x34e/0x4d0
  [] kobject_add+0x75/0xd0
  [] ? mutex_lock+0x12/0x2f
  [] device_add+0x125/0x610
  [] device_create_groups_vargs+0xd8/0x100
  [] device_create_vargs+0x1c/0x20
  [] bdi_register+0x8c/0x180
  [] bdi_register_dev+0x27/0x30
  [] add_disk+0x175/0x4a0

Reported-by: Yi Zhang 
Tested-by: Yi Zhang 
Signed-off-by: Dan Williams 

Fixed up missing 0 return in bdi_register_owner().

Signed-off-by: Jens Axboe 
Signed-off-by: Ben Hutchings

mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progress

2016-02-25T10:34:43+00:00

commit 564e81a57f9788b1475127012e0fd44e9049e342 upstream.

Jan Stancek has reported that system occasionally hanging after "oom01"
testcase from LTP triggers OOM.  Guessing from a result that there is a
kworker thread doing memory allocation and the values between "Node 0
Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not
up-to-date for some reason.

According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to
discover memory reclaim doesn't make any progress"), it meant to force
the kworker thread to take a short sleep, but it by error used
schedule_timeout(1).  We missed that schedule_timeout() in state
TASK_RUNNING doesn't do anything.

Fix it by using schedule_timeout_uninterruptible(1) which forces the
kworker thread to take a short sleep in order to make sure that vmstat
is up-to-date.

Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress")
Signed-off-by: Tetsuo Handa 
Reported-by: Jan Stancek 
Acked-by: Michal Hocko 
Cc: Tejun Heo 
Cc: Cristopher Lameter 
Cc: Joonsoo Kim 
Cc: Arkadiusz Miskiewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Luis Henriques

mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress

2016-01-25T10:42:14+00:00

commit 373ccbe5927034b55bdc80b0f8b54d6e13fe8d12 upstream.

Tetsuo Handa has reported that the system might basically livelock in
OOM condition without triggering the OOM killer.

The issue is caused by internal dependency of the direct reclaim on
vmstat counter updates (via zone_reclaimable) which are performed from
the workqueue context.  If all the current workers get assigned to an
allocation request, though, they will be looping inside the allocator
trying to reclaim memory but zone_reclaimable can see stalled numbers so
it will consider a zone reclaimable even though it has been scanned way
too much.  WQ concurrency logic will not consider this situation as a
congested workqueue because it relies that worker would have to sleep in
such a situation.  This also means that it doesn't try to spawn new
workers or invoke the rescuer thread if the one is assigned to the
queue.

In order to fix this issue we need to do two things.  First we have to
let wq concurrency code know that we are in trouble so we have to do a
short sleep.  In order to prevent from issues handled by 0e093d99763e
("writeback: do not sleep on the congestion queue if there are no
congested BDIs or if significant congestion is not being encountered in
the current zone") we limit the sleep only to worker threads which are
the ones of the interest anyway.

The second thing to do is to create a dedicated workqueue for vmstat and
mark it WQ_MEM_RECLAIM to note it participates in the reclaim and to
have a spare worker thread for it.

Signed-off-by: Michal Hocko 
Reported-by: Tetsuo Handa 
Cc: Tejun Heo 
Cc: Cristopher Lameter 
Cc: Joonsoo Kim 
Cc: Arkadiusz Miskiewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Cc: Ben Hutchings 
[ luis: backported to 3.16, based on Ben's backport to 3.2:
  - use queue_delayed_work instead of queue_delayed_work_on in function
    vmstat_update()
  - change start_cpu_timer() instead of vmstat_shepherd()
  - adjusted context ]
Signed-off-by: Luis Henriques

arch: Mass conversion of smp_mb__*()

2014-04-18T12:20:48+00:00

Mostly scripted conversion of the smp_mb__* barriers.

Signed-off-by: Peter Zijlstra 
Acked-by: Paul E. McKenney 
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar

bdi: avoid oops on device removal

2014-04-03T23:20:49+00:00

After commit 839a8e8660b6 ("writeback: replace custom worker pool
implementation with unbound workqueue") when device is removed while we
are writing to it we crash in bdi_writeback_workfn() ->
set_worker_desc() because bdi->dev is NULL.

This can happen because even though bdi_unregister() cancels all pending
flushing work, nothing really prevents new ones from being queued from
balance_dirty_pages() or other places.

Fix the problem by clearing BDI_registered bit in bdi_unregister() and
checking it before scheduling of any flushing work.

Fixes: 839a8e8660b6777e7fe4e80af1a048aebe2b5977

Reviewed-by: Tejun Heo 
Signed-off-by: Jan Kara 
Cc: Derek Basehore 
Cc: Jens Axboe 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

backing_dev: fix hung task on sync

2014-04-03T23:20:49+00:00

bdi_wakeup_thread_delayed() used the mod_delayed_work() function to
schedule work to writeback dirty inodes.  The problem with this is that
it can delay work that is scheduled for immediate execution, such as the
work from sync_inodes_sb().  This can happen since mod_delayed_work()
can now steal work from a work_queue.  This fixes the problem by using
queue_delayed_work() instead.  This is a regression caused by commit
839a8e8660b6 ("writeback: replace custom worker pool implementation with
unbound workqueue").

The reason that this causes a problem is that laptop-mode will change
the delay, dirty_writeback_centisecs, to 60000 (10 minutes) by default.
In the case that bdi_wakeup_thread_delayed() races with
sync_inodes_sb(), sync will be stopped for 10 minutes and trigger a hung
task.  Even if dirty_writeback_centisecs is not long enough to cause a
hung task, we still don't want to delay sync for that long.

We fix the problem by using queue_delayed_work() when we want to
schedule writeback sometime in future.  This function doesn't change the
timer if it is already armed.

For the same reason, we also change bdi_writeback_workfn() to
immediately queue the work again in the case that the work_list is not
empty.  The same problem can happen if the sync work is run on the
rescue worker.

[jack@suse.cz: update changelog, add comment, use bdi_wakeup_thread_delayed()]
Signed-off-by: Derek Basehore 
Reviewed-by: Jan Kara 
Cc: Alexander Viro 
Reviewed-by: Tejun Heo 
Cc: Greg Kroah-Hartman 
Cc: "Darrick J. Wong" 
Cc: Derek Basehore 
Cc: Kees Cook 
Cc: Benson Leung 
Cc: Sonny Rao 
Cc: Luigi Semenzato 
Cc: Jens Axboe 
Cc: Dave Chinner 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/backing-dev.c: check user buffer length before copying data to the related user buffer

2013-09-11T22:58:03+00:00

'*lenp' may be less than "sizeof(kbuf)" so we must check this before the
next copy_to_user().

pdflush_proc_obsolete() is called by sysctl which 'procname' is
"nr_pdflush_threads", if the user passes buffer length less than
"sizeof(kbuf)", it will cause issue.

Signed-off-by: Chen Gang 
Reviewed-by: Jan Kara 
Cc: Tejun Heo 
Cc: Jeff Moyer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

backing-dev: convert class code to use dev_groups

2013-08-20T04:22:34+00:00

The dev_attrs field of struct class is going away soon, dev_groups
should be used instead.  This converts the backing device class code to
use the correct field.

Cc: Andrew Morton 
Cc: Jan Kara 
Cc: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

sysfs.h: add __ATTR_RW() macro

2013-07-16T17:57:36+00:00

A number of parts of the kernel created their own version of this, might
as well have the sysfs core provide it instead.

Reviewed-by: Guenter Roeck 
Tested-by: Guenter Roeck 
Signed-off-by: Greg Kroah-Hartman

drivers: avoid format string in dev_set_name

2013-07-03T23:07:41+00:00

Calling dev_set_name with a single paramter causes it to be handled as a
format string.  Many callers are passing potentially dynamic string
content, so use "%s" in those cases to avoid any potential accidents,
including wrappers like device_create*() and bdi_register().

Signed-off-by: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds