Revision b1dd693e5b9348bd68a80e679e03cf9c0973b01b authored by Daisuke Nishimura on 24 November 2010, 20:57:06 UTC, committed by Linus Torvalds on 24 November 2010, 21:50:44 UTC
__mem_cgroup_try_charge() can be called under down_write(&mmap_sem)(e.g.
mlock does it). This means it can cause deadlock if it races with move charge:
Ex.1)
move charge | try charge
--------------------------------------+------------------------------
mem_cgroup_can_attach() | down_write(&mmap_sem)
mc.moving_task = current | ..
mem_cgroup_precharge_mc() | __mem_cgroup_try_charge()
mem_cgroup_count_precharge() | prepare_to_wait()
down_read(&mmap_sem) | if (mc.moving_task)
-> cannot aquire the lock | -> true
| schedule()
Ex.2)
move charge | try charge
--------------------------------------+------------------------------
mem_cgroup_can_attach() |
mc.moving_task = current |
mem_cgroup_precharge_mc() |
mem_cgroup_count_precharge() |
down_read(&mmap_sem) |
.. |
up_read(&mmap_sem) |
| down_write(&mmap_sem)
mem_cgroup_move_task() | ..
mem_cgroup_move_charge() | __mem_cgroup_try_charge()
down_read(&mmap_sem) | prepare_to_wait()
-> cannot aquire the lock | if (mc.moving_task)
| -> true
| schedule()
To avoid this deadlock, we do all the move charge works (both can_attach() and
attach()) under one mmap_sem section.
And after this patch, we set/clear mc.moving_task outside mc.lock, because we
use the lock only to check mc.from/to.
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 11e7946
| File | Mode | Size |
|---|---|---|
| crush | ||
| Kconfig | -rw-r--r-- | 753 bytes |
| Makefile | -rw-r--r-- | 766 bytes |
| armor.c | -rw-r--r-- | 1.9 KB |
| auth.c | -rw-r--r-- | 5.6 KB |
| auth_none.c | -rw-r--r-- | 2.9 KB |
| auth_none.h | -rw-r--r-- | 536 bytes |
| auth_x.c | -rw-r--r-- | 16.2 KB |
| auth_x.h | -rw-r--r-- | 847 bytes |
| auth_x_protocol.h | -rw-r--r-- | 1.7 KB |
| buffer.c | -rw-r--r-- | 1.4 KB |
| ceph_common.c | -rw-r--r-- | 11.9 KB |
| ceph_fs.c | -rw-r--r-- | 1.7 KB |
| ceph_hash.c | -rw-r--r-- | 2.7 KB |
| ceph_strings.c | -rw-r--r-- | 2.5 KB |
| crypto.c | -rw-r--r-- | 10.2 KB |
| crypto.h | -rw-r--r-- | 1.3 KB |
| debugfs.c | -rw-r--r-- | 6.5 KB |
| messenger.c | -rw-r--r-- | 60.7 KB |
| mon_client.c | -rw-r--r-- | 24.4 KB |
| msgpool.c | -rw-r--r-- | 1.5 KB |
| osd_client.c | -rw-r--r-- | 44.9 KB |
| osdmap.c | -rw-r--r-- | 26.6 KB |
| pagelist.c | -rw-r--r-- | 3.6 KB |
| pagevec.c | -rw-r--r-- | 4.5 KB |
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