On Wed, 9 Mar 2011 13:27:50 -0800 (PST)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
> When a memcg is oom and current has already received a SIGKILL, then give
> it access to memory reserves with a higher scheduling priority so that it
> may quickly exit and free its memory.
>
> This is identical to the global oom killer and is done even before
> checking for panic_on_oom: a pending SIGKILL here while panic_on_oom is
> selected is guaranteed to have come from userspace; the thread only needs
> access to memory reserves to exit and thus we don't unnecessarily panic
> the machine until the kernel has no last resort to free memory.
>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> ---
> mm/oom_kill.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -537,6 +537,17 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
> unsigned int points = 0;
> struct task_struct *p;
>
> + /*
> + * If current has a pending SIGKILL, then automatically select it. The
> + * goal is to allow it to allocate so that it may quickly exit and free
> + * its memory.
> + */
> + if (fatal_signal_pending(current)) {
> + set_thread_flag(TIF_MEMDIE);
> + boost_dying_task_prio(current, NULL);
> + return;
> + }
> +
> check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
> limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
> read_lock(&tasklist_lock);
The code duplication seems a bit gratuitous.
Was it deliberate that mem_cgroup_out_of_memory() ignores the oom
notifier callbacks?
(Why does that notifier list exist at all? Wouldn't it be better to do
this via a vmscan shrinker? Perhaps altered to be passed the scanning
priority?)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>