Due to commit 696453e66630ad45 ("mm, oom: task_will_free_mem should skip
oom_reaped tasks") and patch "mm,oom: Use ALLOC_OOM for OOM victim's last
second allocation.", thread groups sharing the OOM victim's mm without
setting ->signal->oom_mm before task_will_free_mem(current) is called
might fail to try ALLOC_OOM allocation attempt.
Therefore, make sure that all thread groups sharing the OOM victim's mm can
try ALLOC_OOM allocation attempt by calling mark_oom_victim() on all thread
groups sharing the OOM victim's mm, by splitting oom_kill_process() into
"select final victim and print message" part and "kill final victim" part.
Roman is proposing similar change for implementing cgroup-aware OOM killer
at http://lkml.kernel.org/r/20171019185218.12663-2-guro@xxxxxx , and this
patch can be reused for that purpose.
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Fixes: 696453e66630ad45 ("mm, oom: task_will_free_mem should skip oom_reaped tasks")
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
mm/oom_kill.c | 129 ++++++++++++++++++++++++++++++----------------------------
1 file changed, 67 insertions(+), 62 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3b0d0fe..f859144 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -814,6 +814,64 @@ static bool task_will_free_mem(struct task_struct *task)
return ret;
}
+static void __oom_kill_process(struct task_struct *victim)
+{
+ bool can_oom_reap = true;
+ struct task_struct *p;
+ struct task_struct *t;
+ struct mm_struct *mm;
+
+ victim = find_lock_task_mm(victim);
+ if (!victim)
+ return;
+ get_task_struct(victim);
+ /* Get a reference to safely compare mm after task_unlock(victim) */
+ mm = victim->mm;
+ mmgrab(mm);
+ task_unlock(victim);
+
+ /*
+ * Kill all user processes sharing victim's mm and then grant them
+ * access to memory reserves.
+ */
+ rcu_read_lock();
+ for_each_process(p) {
+ if (!process_shares_mm(p, mm))
+ continue;
+ if (is_global_init(p)) {
+ can_oom_reap = false;
+ set_bit(MMF_OOM_SKIP, &mm->flags);
+ pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n",
+ task_pid_nr(victim), victim->comm,
+ task_pid_nr(p), p->comm);
+ continue;
+ }
+ /*
+ * No use_mm() user needs to read from the userspace so we are
+ * ok to reap it.
+ */
+ if (unlikely(p->flags & PF_KTHREAD))
+ continue;
+ /*
+ * We should send SIGKILL before granting access to memory
+ * reserves in order to prevent the OOM victim from depleting
+ * the memory reserves from the user space under its control.
+ */
+ do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
+ t = find_lock_task_mm(p);
+ if (!t)
+ continue;
+ mark_oom_victim(t);
+ task_unlock(t);
+ }
+ rcu_read_unlock();
+
+ if (can_oom_reap)
+ wake_oom_reaper(victim);
+ mmdrop(mm);
+ put_task_struct(victim);
+}
+
static void oom_kill_process(struct oom_control *oc, const char *message)
{
struct task_struct *p = oc->chosen;
@@ -825,7 +883,6 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
unsigned int victim_points = 0;
static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
- bool can_oom_reap = true;
/*
* If the task is already exiting, don't alarm the sysadmin or kill
@@ -833,13 +890,8 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
* so it can die quickly
*/
task_lock(p);
- if (task_will_free_mem(p)) {
- mark_oom_victim(p);
- wake_oom_reaper(p);
- task_unlock(p);
- put_task_struct(p);
- return;
- }
+ if (task_will_free_mem(p))
+ goto kill_victims;
task_unlock(p);
if (__ratelimit(&oom_rs))
@@ -885,66 +937,20 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
put_task_struct(victim);
victim = p;
}
-
- /* Get a reference to safely compare mm after task_unlock(victim) */
mm = victim->mm;
- mmgrab(mm);
/* Raise event before sending signal: task reaper must see this */
count_vm_event(OOM_KILL);
count_memcg_event_mm(mm, OOM_KILL);
- /*
- * We should send SIGKILL before granting access to memory reserves
- * in order to prevent the OOM victim from depleting the memory
- * reserves from the user space under its control.
- */
- do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
- mark_oom_victim(victim);
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
- task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
- K(get_mm_counter(victim->mm, MM_ANONPAGES)),
- K(get_mm_counter(victim->mm, MM_FILEPAGES)),
- K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
+ task_pid_nr(victim), victim->comm, K(mm->total_vm),
+ K(get_mm_counter(mm, MM_ANONPAGES)),
+ K(get_mm_counter(mm, MM_FILEPAGES)),
+ K(get_mm_counter(mm, MM_SHMEMPAGES)));
+kill_victims:
task_unlock(victim);
-
- /*
- * Kill all user processes sharing victim->mm in other thread groups, if
- * any. They don't get access to memory reserves, though, to avoid
- * depletion of all memory. This prevents mm->mmap_sem livelock when an
- * oom killed thread 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.
- */
- rcu_read_lock();
- for_each_process(p) {
- if (!process_shares_mm(p, mm))
- continue;
- if (same_thread_group(p, victim))
- continue;
- if (is_global_init(p)) {
- can_oom_reap = false;
- set_bit(MMF_OOM_SKIP, &mm->flags);
- pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n",
- task_pid_nr(victim), victim->comm,
- task_pid_nr(p), p->comm);
- continue;
- }
- /*
- * No use_mm() user needs to read from the userspace so we are
- * ok to reap it.
- */
- if (unlikely(p->flags & PF_KTHREAD))
- continue;
- do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
- }
- rcu_read_unlock();
-
- if (can_oom_reap)
- wake_oom_reaper(victim);
-
- mmdrop(mm);
+ __oom_kill_process(victim);
put_task_struct(victim);
}
#undef K
@@ -1018,8 +1024,7 @@ bool out_of_memory(struct oom_control *oc)
* quickly exit and free its memory.
*/
if (task_will_free_mem(current)) {
- mark_oom_victim(current);
- wake_oom_reaper(current);
+ __oom_kill_process(current);
return true;
}
--
1.8.3.1
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