2022-01-06 10:21:17

by Jann Horn

[permalink] [raw]
Subject: [PATCH v2] 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.

As documented in struct oom_control, order == -1 means the oom kill is
required by sysrq. So check for that, and if it's true, don't bail out
no matter what the OOM notifiers say.

Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Jann Horn <[email protected]>
---
mm/oom_kill.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1ddabefcfb5a..3c480b24a93c 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1057,7 +1057,7 @@ 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;
}

base-commit: c9e6606c7fe92b50a02ce51dda82586ebdf99b48
--
2.34.1.448.ga2b2bfdf31-goog



2022-01-06 10:22:48

by Jann Horn

[permalink] [raw]
Subject: Re: [PATCH v2] mm, oom: OOM sysrq should always kill a process

On Thu, Jan 6, 2022 at 11:21 AM Jann Horn <[email protected]> wrote:
> 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.
>
> As documented in struct oom_control, order == -1 means the oom kill is
> required by sysrq. So check for that, and if it's true, don't bail out
> no matter what the OOM notifiers say.

Er, sorry, I just noticed after sending this that the commit message
doesn't make sense anymore... I'll send a new version in a sec.