From: Andrew Morton <akpm@linux-foundation.org>
To: Li Zefan <lizefan@huawei.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Michel Lespinasse <walken@google.com>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
"Chandramouleeswaran, Aswin" <aswin@hp.com>,
"Norton, Scott J" <scott.norton@hp.com>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4] mm: per-thread vma caching
Date: Thu, 13 Mar 2014 21:43:08 -0700 [thread overview]
Message-ID: <20140313214308.090d1a18.akpm@linux-foundation.org> (raw)
In-Reply-To: <5322720F.1030706@huawei.com>
On Fri, 14 Mar 2014 11:05:51 +0800 Li Zefan <lizefan@huawei.com> wrote:
> Hi Davidlohr,
>
> On 2014/3/4 11:26, Linus Torvalds wrote:
> > On Mon, Mar 3, 2014 at 7:13 PM, Davidlohr Bueso <davidlohr@hp.com> wrote:
> >>
> >> Yes, I shortly realized that was silly... but I can say for sure it can
> >> happen and a quick qemu run confirms it. So I see your point as to
> >> asking why we need it, so now I'm looking for an explanation in the
> >> code.
> >
> > We definitely *do* have users.
> >
> > One example would be ptrace -> access_process_vm -> __access_remote_vm
> > -> get_user_pages() -> find_extend_vma() -> find_vma_prev -> find_vma.
> >
>
> I raw this oops on 3.14.0-rc5-next-20140307, which is possible caused by
> your patch? Don't know how it was triggered.
>
> ...
>
> [ 6072.027007] [<ffffffff811a4f62>] get_user_pages+0x52/0x60
> [ 6072.027015] [<ffffffff811a5088>] __access_remote_vm+0x118/0x1f0
> [ 6072.027023] [<ffffffff811a51bb>] access_process_vm+0x5b/0x80
> [ 6072.027033] [<ffffffff812675a7>] proc_pid_cmdline+0x77/0x120
> [ 6072.027041] [<ffffffff81267da2>] proc_info_read+0xa2/0xe0
> [ 6072.027050] [<ffffffff811f439d>] vfs_read+0xad/0x1a0
> [ 6072.027057] [<ffffffff811f45b5>] SyS_read+0x65/0xb0
> [ 6072.027066] [<ffffffff8159ba12>] system_call_fastpath+0x16/0x1b
> [ 6072.027072] Code: f4 4c 89 f7 89 45 a4 e8 36 0e eb ff 48 3d 00 f0 ff ff 48 89 c3 0f 86 d7 00 00 00 4c 89 e0
> 49 8b 56 40 48 c1 e8 27 25 ff 01 00 00 <48> 8b 0c c2 48 85 c9 75 3e 41 83 e5 08 74 1b 49 8b 87 90 00 00
> [ 6072.027134] RIP [<ffffffff811a0189>] follow_page_mask+0x69/0x620
> [ 6072.027142] RSP <ffff880618855c18>
> [ 6072.027146] CR2: 00000000000007f8
Yep. Please grab whichever of
mm-per-thread-vma-caching-fix-3.patch
mm-per-thread-vma-caching-fix-4.patch
mm-per-thread-vma-caching-fix-5.patch
mm-per-thread-vma-caching-fix-6-checkpatch-fixes.patch
mm-per-thread-vma-caching-fix-6-fix.patch
which you don't have from http://ozlabs.org/~akpm/mmots/broken-out/
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next prev parent reply other threads:[~2014-03-14 4:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-27 21:48 [PATCH v4] mm: per-thread vma caching Davidlohr Bueso
2014-02-28 4:39 ` Davidlohr Bueso
2014-03-04 0:00 ` Andrew Morton
2014-03-04 0:18 ` Davidlohr Bueso
2014-03-04 0:40 ` Andrew Morton
2014-03-04 0:59 ` Davidlohr Bueso
2014-03-04 1:23 ` Andrew Morton
2014-03-04 2:42 ` Davidlohr Bueso
2014-03-04 3:12 ` Andrew Morton
2014-03-04 3:13 ` Davidlohr Bueso
2014-03-04 3:26 ` Andrew Morton
2014-03-04 3:26 ` Linus Torvalds
2014-03-04 5:32 ` Davidlohr Bueso
2014-03-14 3:05 ` Li Zefan
2014-03-14 4:43 ` Andrew Morton [this message]
2014-03-06 22:56 ` Andrew Morton
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