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authorLi Zefan <lizf@cn.fujitsu.com>2008-04-15 14:34:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-15 19:35:40 -0700
commite115f2d89253490fb2dbf304b627f8d908df26f1 (patch)
treecfed18e5ac01247f6edbf0d72b418b9e7e110265
parente169c139642fb4c682ec12a409725508dbefa520 (diff)
downloadlinux-e115f2d89253490fb2dbf304b627f8d908df26f1.tar.gz
linux-e115f2d89253490fb2dbf304b627f8d908df26f1.tar.xz
memcg: fix oops in oom handling
When I used a test program to fork mass processes and immediately move them to a cgroup where the memory limit is low enough to trigger oom kill, I got oops: BUG: unable to handle kernel NULL pointer dereference at 0000000000000808 IP: [<ffffffff8045c47f>] _spin_lock_irqsave+0x8/0x18 PGD 4c95f067 PUD 4406c067 PMD 0 Oops: 0002 [1] SMP CPU 2 Modules linked in: Pid: 11973, comm: a.out Not tainted 2.6.25-rc7 #5 RIP: 0010:[<ffffffff8045c47f>] [<ffffffff8045c47f>] _spin_lock_irqsave+0x8/0x18 RSP: 0018:ffff8100448c7c30 EFLAGS: 00010002 RAX: 0000000000000202 RBX: 0000000000000009 RCX: 000000000001c9f3 RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000808 RBP: ffff81007e444080 R08: 0000000000000000 R09: ffff8100448c7900 R10: ffff81000105f480 R11: 00000100ffffffff R12: ffff810067c84140 R13: 0000000000000001 R14: ffff8100441d0018 R15: ffff81007da56200 FS: 00007f70eb1856f0(0000) GS:ffff81007fbad3c0(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000808 CR3: 000000004498a000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process a.out (pid: 11973, threadinfo ffff8100448c6000, task ffff81007da533e0) Stack: ffffffff8023ef5a 00000000000000d0 ffffffff80548dc0 00000000000000d0 ffff810067c84140 ffff81007e444080 ffffffff8026cef9 00000000000000d0 ffff8100441d0000 00000000000000d0 ffff8100441d0000 ffff8100505445c0 Call Trace: [<ffffffff8023ef5a>] ? force_sig_info+0x25/0xb9 [<ffffffff8026cef9>] ? oom_kill_task+0x77/0xe2 [<ffffffff8026d696>] ? mem_cgroup_out_of_memory+0x55/0x67 [<ffffffff802910ad>] ? mem_cgroup_charge_common+0xec/0x202 [<ffffffff8027997b>] ? handle_mm_fault+0x24e/0x77f [<ffffffff8022c4af>] ? default_wake_function+0x0/0xe [<ffffffff8027a17a>] ? get_user_pages+0x2ce/0x3af [<ffffffff80290fee>] ? mem_cgroup_charge_common+0x2d/0x202 [<ffffffff8027a441>] ? make_pages_present+0x8e/0xa4 [<ffffffff8027d1ab>] ? mmap_region+0x373/0x429 [<ffffffff8027d7eb>] ? do_mmap_pgoff+0x2ff/0x364 [<ffffffff80210471>] ? sys_mmap+0xe5/0x111 [<ffffffff8020bfc9>] ? tracesys+0xdc/0xe1 Code: 00 00 01 48 8b 3c 24 e9 46 d4 dd ff f0 ff 07 48 8b 3c 24 e9 3a d4 dd ff fe 07 48 8b 3c 24 e9 2f d4 dd ff 9c 58 fa ba 00 01 00 00 <f0> 66 0f c1 17 38 f2 74 06 f3 90 8a 17 eb f6 c3 fa b8 00 01 00 RIP [<ffffffff8045c47f>] _spin_lock_irqsave+0x8/0x18 RSP <ffff8100448c7c30> CR2: 0000000000000808 ---[ end trace c3702fa668021ea4 ]--- It's reproducable in a x86_64 box, but doesn't happen in x86_32. This is because tsk->sighand is not guarded by RCU, so we have to hold tasklist_lock, just as what out_of_memory() does. Signed-off-by: Li Zefan <lizf@cn.fujitsu> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelianov <xemul@openvz.org> Cc: Paul Menage <menage@google.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: David Rientjes <rientjes@cs.washington.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/oom_kill.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f255eda..beb592f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -423,7 +423,7 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
struct task_struct *p;
cgroup_lock();
- rcu_read_lock();
+ read_lock(&tasklist_lock);
retry:
p = select_bad_process(&points, mem);
if (PTR_ERR(p) == -1UL)
@@ -436,7 +436,7 @@ retry:
"Memory cgroup out of memory"))
goto retry;
out:
- rcu_read_unlock();
+ read_unlock(&tasklist_lock);
cgroup_unlock();
}
#endif