linux-kernel - Re: [PATCH v2] mm: fix account pmd page to the process

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Date:	Fri, 17 Jun 2016 15:20:38 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	zhongjiang <zhongjiang@...wei.com>
Cc:	mike.kravetz@...cle.com, kirill@...temov.name, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm: fix account pmd page to the process

On Fri 17-06-16 21:13:12, zhongjiang wrote:
> From: zhong jiang <zhongjiang@...wei.com>
> 
> huge_pmd_share accounts the number of pmds incorrectly when it races
> with a parallel pud instantiation. vma_interval_tree_foreach will
> increase the counter but then has to recheck the pud with the pte lock
> held and the back off path should drop the increment. The previous
> code would lead to an elevated pmd count which shouldn't be very
> harmful (check_mm() might complain and oom_badness() might be marginally
> confused) but this is worth fixing.

Kirill has posted a patch which is imho better [1]

[1] http://lkml.kernel.org/r/20160617122506.GC6534@node.shutemov.name
-- 
Michal Hocko
SUSE Labs