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From: Hugh Dickins <hughd@google.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Michel Lespinasse <walken@google.com>,
	Sasha Levin <levinsasha928@gmail.com>,
	linux-mm@kvack.org, riel@redhat.com, peterz@infradead.org,
	aarcange@redhat.com, daniel.santos@pobox.com,
	linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	Dave Jones <davej@redhat.com>
Subject: Re: [PATCH 6/7] mm: add CONFIG_DEBUG_VM_RB build option
Date: Sun, 16 Sep 2012 12:07:40 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LSU.2.00.1209161130460.5591@eggly.anvils> (raw)
In-Reply-To: <505433A0.3010702@suse.cz>

On Sat, 15 Sep 2012, Jiri Slaby wrote:
> On 09/15/2012 02:00 AM, Michel Lespinasse wrote:
> > All right. Hugh managed to reproduce the issue on his suse laptop, and
> > I came up with a fix.
> > 
> > The problem was that in mremap, the new vma's vm_{start,end,pgoff}
> > fields need to be updated before calling anon_vma_clone() so that the
> > new vma will be properly indexed.
> > 
> > Patch attached. I expect this should also explain Jiri's reported
> > failure involving splitting THP pages during mremap(), even though we
> > did not manage to reproduce that one.
> 
> Oh, great. This is BTW also machine with suse.

We guessed that for you it might be :)
I've not yet moved up from 11.4 by the way, if that makes a difference.

In fact, even before these reports, when Michel was wondering about the
uses of mremap, I did mention an mremap/THP bug from a year ago, which
the SuSE update had been good for reproducing.

> What was the way that
> Hugh used to reproduce the other issue?

I've lost track of which issue is "other".

To reproduce Sasha's interval_tree.c warnings, all I had to do was switch
on CONFIG_DEBUG_VM_RB (I regret not having done so before) and boot up.

I didn't look to see what was doing the mremap which caused the warning
until now: surprisingly, it's microcode_ctl.  I've not made much effort
to get the right set of sources and work out why that would be using
mremap (a realloc inside a library?).

I failed to reproduce your BUG in huge_memory.c, but what I was trying
was SuSE update via yast2, on several machines; but perhaps because
they were all fairly close to up-to-date, I didn't hit a problem.
(That was before I turned on DEBUG_VM_RB for Sasha's.)

Hugh

> For me it happened twice in a
> row when using zypper to upgrade packages. But it did not happen any
> more after that.
> 
> thanks,
> -- 
> js
> suse labs

  reply	other threads:[~2012-09-16 19:08 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-04  9:20 [PATCH 0/7] use interval trees for anon rmap Michel Lespinasse
2012-09-04  9:20 ` [PATCH 1/7] mm: interval tree updates Michel Lespinasse
2012-09-07 22:13   ` Andrew Morton
2012-09-07 22:29     ` Michel Lespinasse
2012-09-07 22:55       ` Andrew Morton
2012-09-07 23:26         ` Michel Lespinasse
2012-09-08  4:45           ` Hillf Danton
2012-09-07 23:26         ` Michel Lespinasse
2012-09-04  9:20 ` [PATCH 2/7] mm: fix potential anon_vma locking issue in mprotect() Michel Lespinasse
2012-09-04 14:27   ` Andrea Arcangeli
2012-09-04 21:53     ` Michel Lespinasse
2012-09-04 22:16       ` Andrea Arcangeli
2012-09-05  0:45         ` Michel Lespinasse
2012-09-04  9:20 ` [PATCH 3/7] mm anon rmap: remove anon_vma_moveto_tail Michel Lespinasse
2012-09-04  9:20 ` [PATCH 4/7] mm anon rmap: replace same_anon_vma linked list with an interval tree Michel Lespinasse
2012-09-05  0:51   ` Michel Lespinasse
2012-09-04  9:20 ` [PATCH 5/7] mm rmap: remove vma_address check for address inside vma Michel Lespinasse
2012-09-04  9:20 ` [PATCH 6/7] mm: add CONFIG_DEBUG_VM_RB build option Michel Lespinasse
2012-09-14 22:14   ` Sasha Levin
2012-09-14 22:40     ` Sasha Levin
2012-09-14 22:46     ` Michel Lespinasse
2012-09-15  0:00       ` Michel Lespinasse
2012-09-15  7:52         ` Jiri Slaby
2012-09-16 19:07           ` Hugh Dickins [this message]
2012-09-22  7:19             ` Jiri Slaby
2012-09-15  9:26         ` Sasha Levin
2012-09-20 21:39           ` Fengguang Wu
2012-09-20 22:27             ` Hugh Dickins
2012-09-20 22:31               ` Fengguang Wu
2012-09-04  9:20 ` [PATCH 7/7] mm: avoid taking rmap locks in move_ptes() Michel Lespinasse

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