[Adding Eric to CC] On Thu 14-11-13 15:26:51, David Rientjes wrote: > When current has a pending SIGKILL or is already in the exit path, it > only needs access to memory reserves to fully exit. In that sense, the > memcg is not actually oom for current, it simply needs to bypass memory > charges to exit and free its memory, which is guarantee itself that > memory will be freed. > > We only want to notify userspace for actionable oom conditions where > something needs to be done (and all oom handling can already be deferred > to userspace through this method by disabling the memcg oom killer with > memory.oom_control), not simply when a memcg has reached its limit, which > would actually have to happen before memcg reclaim actually frees memory > for charges.
I believe this also fixes the issue reported by Eric (https://lkml.org/lkml/2013/7/28/74). I had a patch for this https://lkml.org/lkml/2013/7/31/94 but the code changed since then and this should be equivalent. > Reported-by: Johannes Weiner <han...@cmpxchg.org> > Signed-off-by: David Rientjes <rient...@google.com> > --- > mm/memcontrol.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1783,16 +1783,6 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup > *memcg, gfp_t gfp_mask, > unsigned int points = 0; > struct task_struct *chosen = NULL; > > - /* > - * If current has a pending SIGKILL or is exiting, 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) || current->flags & PF_EXITING) { > - set_thread_flag(TIF_MEMDIE); > - return; > - } > - > check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL); > totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1; > for_each_mem_cgroup_tree(iter, memcg) { > @@ -2243,6 +2233,16 @@ bool mem_cgroup_oom_synchronize(bool handle) > if (!handle) > goto cleanup; > > + /* > + * If current has a pending SIGKILL or is exiting, 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) || current->flags & PF_EXITING) { > + set_thread_flag(TIF_MEMDIE); > + goto cleanup; > + } > + > owait.memcg = memcg; > owait.wait.flags = 0; > owait.wait.func = memcg_oom_wake_function; -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
