Messages in this thread Patch in this message | | | From | Gaurav Kohli <> | Subject | [PATCH] mm: oom: Fix race condition between oom_badness and do_exit of task | Date | Wed, 7 Mar 2018 18:27:34 +0530 |
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oom_badness access real_cred of task for calculation without increasing the usage counter of task struct. This may create a race if do_exit of same task runs and free the real_cred. So using get_task_struct which blocks the freeing until oom_badness is executing.
el1_da+0x24/0x84 security_capable_noaudit+0x64/0x94 has_capability_noaudit+0x38/0x58 oom_badness.part.21+0x114/0x1c0 oom_badness+0x50/0x5c proc_oom_score+0x48/0x80 proc_single_show+0x5c/0xb8
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 6fd9773..5f4cc4b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -114,9 +114,11 @@ struct task_struct *find_lock_task_mm(struct task_struct *p) for_each_thread(p, t) { task_lock(t); + get_task_struct(t); if (likely(t->mm)) goto found; task_unlock(t); + put_task_struct(t); } t = NULL; found: @@ -191,6 +193,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, test_bit(MMF_OOM_SKIP, &p->mm->flags) || in_vfork(p)) { task_unlock(p); + put_task_struct(p); return 0; } @@ -208,7 +211,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, */ if (has_capability_noaudit(p, CAP_SYS_ADMIN)) points -= (points * 3) / 100; - + put_task_struct(p); /* Normalize to oom_score_adj units */ adj *= totalpages / 1000; points += adj; -- 1.9.1
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