diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2014-12-12 16:56:24 -0800 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2019-05-02 18:57:22 +0200 |
| commit | baef704101598ac1b3eef38e71da3c180ecfcd30 (patch) | |
| tree | 76d7ecd19b8b8caad8d4cc01ce174e97dd5c5958 /mm | |
| parent | 1290125a2f1265d7fc4bd11c7dcec4183eceb31b (diff) | |
oom: don't assume that a coredumping thread will exit soon
oom_kill.c assumes that PF_EXITING task should exit and free the memory
soon. This is wrong in many ways and one important case is the coredump.
A task can sleep in exit_mm() "forever" while the coredumping sub-thread
can need more memory.
Change the PF_EXITING checks to take SIGNAL_GROUP_COREDUMP into account,
we add the new trivial helper for that.
Note: this is only the first step, this patch doesn't try to solve other
problems. The SIGNAL_GROUP_COREDUMP check is obviously racy, a task can
participate in coredump after it was already observed in PF_EXITING state,
so TIF_MEMDIE (which also blocks oom-killer) still can be wrongly set.
fatal_signal_pending() can be true because of SIGNAL_GROUP_COREDUMP so
out_of_memory() and mem_cgroup_out_of_memory() shouldn't blindly trust it.
And even the name/usage of the new helper is confusing, an exiting thread
can only free its ->mm if it is the only/last task in thread group.
[akpm@linux-foundation.org: add comment]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change-Id: I6a69bf26a477f31e733ed6911da4f299d49cdfe1
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 2 | ||||
| -rw-r--r-- | mm/oom_kill.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d6d5a7ea9..cb9dc56d3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1812,7 +1812,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, * select it. The goal is to allow it to allocate so that it may * quickly exit and free its memory. */ - if (fatal_signal_pending(current) || current->flags & PF_EXITING) { + if (fatal_signal_pending(current) || task_will_free_mem(current)) { set_thread_flag(TIF_MEMDIE); return; } diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 1093dcd15..479d1723a 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -455,7 +455,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, * If the task is already exiting, don't alarm the sysadmin or kill * its children or threads, just set TIF_MEMDIE so it can die quickly */ - if (p->flags & PF_EXITING) { + if (task_will_free_mem(p)) { set_tsk_thread_flag(p, TIF_MEMDIE); last_victim = jiffies; put_task_struct(p); @@ -688,7 +688,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, * select it. The goal is to allow it to allocate so that it may * quickly exit and free its memory. */ - if (fatal_signal_pending(current) || current->flags & PF_EXITING) { + if (fatal_signal_pending(current) || task_will_free_mem(current)) { set_thread_flag(TIF_MEMDIE); last_victim = jiffies; return; |