On Mon 19-03-18 14:10:05, David Rientjes wrote:
> Commit 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and
> madvised allocations") changed the page allocator to no longer detect thp
> allocations based on __GFP_NORETRY.
>
> It did not, however, modify the mem cgroup try_charge() path to avoid oom
> kill for either khugepaged collapsing or thp faulting. It is never
> expected to oom kill a process to allocate a hugepage for thp; reclaim is
> governed by the thp defrag mode and MADV_HUGEPAGE, but allocations (and
> charging) should fallback instead of oom killing processes.
For some reason I thought that the charging path simply bails out for
costly orders - effectively the same thing as for the global OOM killer.
But we do not. Is there any reason to not do that though? Why don't we
simply do
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d1a917b5b7b7..08accbcd1a18 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1493,7 +1493,7 @@ static void memcg_oom_recover(struct mem_cgroup *memcg)
static void mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
{
- if (!current->memcg_may_oom)
+ if (!current->memcg_may_oom || order > PAGE_ALLOC_COSTLY_ORDER)
return;
/*
* We are in the middle of the charge context here, so we
--
Michal Hocko
SUSE Labs
