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-rw-r--r--mm/oom_kill.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4395f371bc7c..7dcca55ede7c 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -404,16 +404,40 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
#define K(x) ((x) << (PAGE_SHIFT-10))
static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
{
+ struct task_struct *q;
+ struct mm_struct *mm;
+
p = find_lock_task_mm(p);
if (!p)
return 1;
+ /* mm cannot be safely dereferenced after task_unlock(p) */
+ mm = p->mm;
+
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
task_pid_nr(p), p->comm, K(p->mm->total_vm),
K(get_mm_counter(p->mm, MM_ANONPAGES)),
K(get_mm_counter(p->mm, MM_FILEPAGES)));
task_unlock(p);
+ /*
+ * Kill all processes sharing p->mm in other thread groups, if any.
+ * They don't get access to memory reserves or a higher scheduler
+ * priority, though, to avoid depletion of all memory or task
+ * starvation. This prevents mm->mmap_sem livelock when an oom killed
+ * task cannot exit because it requires the semaphore and its contended
+ * by another thread trying to allocate memory itself. That thread will
+ * now get access to memory reserves since it has a pending fatal
+ * signal.
+ */
+ for_each_process(q)
+ if (q->mm == mm && !same_thread_group(q, p)) {
+ task_lock(q); /* Protect ->comm from prctl() */
+ pr_err("Kill process %d (%s) sharing same memory\n",
+ task_pid_nr(q), q->comm);
+ task_unlock(q);
+ force_sig(SIGKILL, q);
+ }
set_tsk_thread_flag(p, TIF_MEMDIE);
force_sig(SIGKILL, p);