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From: Michal Hocko <mhocko@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	linux-mm@kvack.org, linux-next@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [linux-next: Tree for Jun 1] __khugepaged_exit rwsem_down_write_failed lockup
Date: Fri, 3 Jun 2016 09:25:36 +0200	[thread overview]
Message-ID: <20160603072536.GB20676@dhcp22.suse.cz> (raw)
In-Reply-To: <20160603071551.GA453@swordfish>

On Fri 03-06-16 16:15:51, Sergey Senozhatsky wrote:
> Hello,
> 
> On (06/02/16 11:21), Michal Hocko wrote:
> [..]
> > @@ -2863,6 +2854,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
> >  
> >  		collect_mm_slot(mm_slot);
> >  	}
> > +	mmput(mm);
> >  
> >  	return progress;
> >  }
> 
> this possibly sleeping mmput() is called from
> under the spin_lock(&khugepaged_mm_lock).

You are right. khugepaged_scan_mm_slot returns with the lock held.
mmput_async would deal with it.
 
> there is also a trivial build fixup needed
> (move collect_mm_slot() before __khugepaged_exit()).

will fix that. Thanks!

> it's quite hard to trigger the bug (somehow), so I can't
> follow up with more information as of now.

Thanks anyway!
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2016-06-03  7:25 UTC|newest]

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 [this message]
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
2016-06-09  3:51         ` Sergey Senozhatsky

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