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 /include | |
| 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 'include')
| -rw-r--r-- | include/linux/oom.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/oom.h b/include/linux/oom.h index fbb0bead6..3ce57d6cf 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -87,6 +87,17 @@ static inline void oom_killer_enable(void) extern struct task_struct *find_lock_task_mm(struct task_struct *p); +static inline bool task_will_free_mem(struct task_struct *task) +{ + /* + * A coredumping process may sleep for an extended period in exit_mm(), + * so the oom killer cannot assume that the process will promptly exit + * and release memory. + */ + return (task->flags & PF_EXITING) && + !(task->signal->flags & SIGNAL_GROUP_COREDUMP); +} + extern void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemask); |