mm, oom: OOM sysrq should always kill a process

The OOM kill sysrq (alt+sysrq+F) should allow the user to kill the
process with the highest OOM badness with a single execution.

However, at the moment, the OOM kill can bail out if an OOM notifier
(e.g.  the i915 one) says that it reclaimed a tiny amount of memory from
somewhere.  That's probably not what the user wants, so skip the bailout
if the OOM was triggered via sysrq.

Link: https://lkml.kernel.org/r/20220106102605.635656-1-jannh@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3390316..3934ff5 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1058,7 +1058,7 @@ bool out_of_memory(struct oom_control *oc)
 
        if (!is_memcg_oom(oc)) {
                blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
-               if (freed > 0)
+               if (freed > 0 && !is_sysrq_oom(oc))
                        /* Got some memory back in the last second. */
                        return true;
        }