On Thu 06-12-12 11:12:49, azurIt wrote:

quoted

Dohh. The very same stack mem_cgroup_newpage_charge called from the page
fault. The heavy inlining is not particularly helping here... So there
must be some other THP charge leaking out.
[/me is diving into the code again]

* do_huge_pmd_anonymous_page falls back to handle_pte_fault
* do_huge_pmd_wp_page_fallback falls back to simple pages so it doesn't
 charge the huge page
* do_huge_pmd_wp_page splits the huge page and retries with fallback to
 handle_pte_fault
* collapse_huge_page is not called in the page fault path
* do_wp_page, do_anonymous_page and __do_fault  operate on a single page
 so the memcg charging cannot return ENOMEM

There are no other callers AFAICS so I am getting clueless. Maybe more
debugging will tell us something (the inlining has been reduced for thp
paths which can reduce performance in thp page fault heavy workloads but
this will give us better traces - I hope).

Should i apply all patches togather? (fix for this bug, more log
messages, backported fix from 3.5 and this new one)

Yes please
-- 
Michal Hocko
SUSE Labs

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