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From: Vlastimil Babka <vbabka@suse.cz>
To: Ebru Akagunduz <ebru.akagunduz@gmail.com>, akpm@linux-foundation.org
Cc: sergey.senozhatsky.work@gmail.com, mhocko@kernel.org,
	kirill.shutemov@linux.intel.com, sfr@canb.auug.org.au,
	linux-mm@kvack.org, linux-next@vger.kernel.org,
	linux-kernel@vger.kernel.org, riel@redhat.com,
	aarcange@redhat.com
Subject: Re: [PATCH] mm, thp: fix locking inconsistency in collapse_huge_page
Date: Mon, 6 Jun 2016 15:05:19 +0200
Message-ID: <12918dcd-a695-c6f4-e06f-69141c5f357f@suse.cz> (raw)
In-Reply-To: <1464956884-4644-1-git-send-email-ebru.akagunduz@gmail.com>

On 06/03/2016 02:28 PM, Ebru Akagunduz wrote:
> After creating revalidate vma function, locking inconsistency occured
> due to directing the code path to wrong label. This patch directs
> to correct label and fix the inconsistency.
>
> Related commit that caused inconsistency:
> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=da4360877094368f6dfe75bbe804b0f0a5d575b0
>
> Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>

I think this does fix the inconsistency, thanks.

But looking at collapse_huge_page() as of latest -next, I wonder if 
there's another problem:

pmd = mm_find_pmd(mm, address);
...
up_read(&mm->mmap_sem);
down_write(&mm->mmap_sem);
hugepage_vma_revalidate(mm, address);
...
pte = pte_offset_map(pmd, address);

What guarantees that 'pmd' is still valid?

Vlastimil

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  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-01  3:11 linux-next: Tree for Jun 1 Stephen Rothwell
2016-06-02  1:48 ` [linux-next: Tree for Jun 1] __khugepaged_exit rwsem_down_write_failed lockup Sergey Senozhatsky
2016-06-02  9:21   ` Michal Hocko
2016-06-02 12:08     ` Sergey Senozhatsky
2016-06-02 12:21       ` Michal Hocko
2016-06-03 13:51         ` Andrea Arcangeli
2016-06-03 14:46           ` Michal Hocko
2016-06-03 15:10             ` Andrea Arcangeli
2016-06-07  7:34               ` Michal Hocko
2016-06-08  8:19               ` Vlastimil Babka
2016-06-03  7:15     ` Sergey Senozhatsky
2016-06-03  7:25       ` Michal Hocko
2016-06-03  8:43         ` Sergey Senozhatsky
2016-06-03  9:55           ` Michal Hocko
2016-06-03 10:05             ` Michal Hocko
2016-06-03 13:38               ` Sergey Senozhatsky
2016-06-03 13:45                 ` Michal Hocko
2016-06-03 13:49                   ` Michal Hocko
2016-06-04  7:51                     ` Sergey Senozhatsky
2016-06-06  8:39                       ` Michal Hocko
2016-06-02 13:24   ` Vlastimil Babka
2016-06-02 18:58     ` Ebru Akagunduz
2016-06-03  1:00       ` Sergey Senozhatsky
2016-06-03  1:29         ` Sergey Senozhatsky
2016-06-03  4:14           ` Sergey Senozhatsky
2016-06-03 12:28     ` [PATCH] mm, thp: fix locking inconsistency in collapse_huge_page Ebru Akagunduz
2016-06-06 13:05       ` Vlastimil Babka [this message]
2016-06-09  3:51         ` Sergey Senozhatsky

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