From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: zhong jiang <zhongjiang@huawei.com>
Cc: mhocko@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/huge_memory: fix the memory leak due to the race
Date: Tue, 21 Jun 2016 18:29:20 +0300 [thread overview]
Message-ID: <20160621152920.GA7760@node.shutemov.name> (raw)
In-Reply-To: <57695AEB.8030509@huawei.com>
On Tue, Jun 21, 2016 at 11:19:07PM +0800, zhong jiang wrote:
> On 2016/6/21 22:37, Kirill A. Shutemov wrote:
> > On Tue, Jun 21, 2016 at 10:05:56PM +0800, zhongjiang wrote:
> >> From: zhong jiang <zhongjiang@huawei.com>
> >>
> >> with great pressure, I run some test cases. As a result, I found
> >> that the THP is not freed, it is detected by check_mm().
> >>
> >> BUG: Bad rss-counter state mm:ffff8827edb70000 idx:1 val:512
> >>
> >> Consider the following race :
> >>
> >> CPU0 CPU1
> >> __handle_mm_fault()
> >> wp_huge_pmd()
> >> do_huge_pmd_wp_page()
> >> pmdp_huge_clear_flush_notify()
> >> (pmd_none = true)
> >> exit_mmap()
> >> unmap_vmas()
> >> zap_pmd_range()
> >> pmd_none_or_trans_huge_or_clear_bad()
> >> (result in memory leak)
> >> set_pmd_at()
> >>
> >> because of CPU0 have allocated huge page before pmdp_huge_clear_notify,
> >> and it make the pmd entry to be null. Therefore, The memory leak can occur.
> >>
> >> The patch fix the scenario that the pmd entry can lead to be null.
> > I don't think the scenario is possible.
> >
> > exit_mmap() called when all mm users have gone, so no parallel threads
> > exist.
> >
> Forget this patch. It 's my fault , it indeed don not exist.
> But I hit the following problem. we can see the memory leak when the process exit.
>
>
> Any suggestion will be apprecaited.
Could you try this:
http://lkml.kernel.org/r/20160621150433.GA7536@node.shutemov.name
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2016-06-21 15:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 14:05 [PATCH] mm/huge_memory: fix the memory leak due to the race zhongjiang
2016-06-21 14:32 ` kbuild test robot
2016-06-21 14:37 ` Kirill A. Shutemov
2016-06-21 15:19 ` zhong jiang
2016-06-21 15:29 ` Kirill A. Shutemov [this message]
2016-06-22 2:55 ` zhong jiang
2016-06-22 9:52 ` zhong jiang
2016-06-21 14:37 ` Michal Hocko
2016-06-21 14:42 ` kbuild test robot
-- strict thread matches above, loose matches on Subject: below --
2016-06-21 14:57 zhongjiang
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