linux-kernel - Re: perf bug: bad page map

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Message-ID: <alpine.DEB.2.10.1311181138390.18020@vincent-weaver-1.um.maine.edu>
Date:	Mon, 18 Nov 2013 11:41:22 -0500 (EST)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Vince Weaver <vincent.weaver@...ne.edu>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	tytso@....edu, adilger.kernel@...ger.ca
Subject: Re: perf bug: bad page map

On Mon, 18 Nov 2013, Peter Zijlstra wrote:

> On Fri, Nov 15, 2013 at 01:04:23PM -0500, Vince Weaver wrote:
> > 
> > (figured out the minicom issue).
> > 
> > Anyway while trying to reproduce the last bug I instead got this with
> > the perf_fuzzer.
> > 
> > Is it worth continuing to run and report these issues?  I'm losing track 
> > of all the open bugs.
> 
> This is looks like ext4. Not entirely sure how perf ties into this.

It's believable the filesystem could have issues (it's a fuzzer machine, 
so it's had 100+ unclean shutdowns on an SSD drive in the past few months)
but as far as I know there shouldn't have been any filesystem accesses 
happening at all when the bug triggered.

I thought it might be perf related due to the perf references in the 
backtrace (and since it was being perf-fuzzed at the time).

> Anyway, yes, I do think its useful to keep running these tests, we do
> fix various issues -- although probably not at the rate you seem to be
> finding them.
> 
> > [ 1618.118179] BUG: Bad page map in process perf_fuzzer  pte:ffff8800c4d60040 pmd:bd86a067
> > [ 1618.142177] addr:0000000000409000 vm_flags:00000875 anon_vma:          (null) mapping:ffff8800cb74adf0 index:9
> > [ 1618.172142] vma->vm_ops->fault: filemap_fault+0x0/0x358
> > [ 1618.187783] vma->vm_file->f_op->mmap: ext4_file_mmap+0x0/0x48
> > [ 1618.204981] CPU: 1 PID: 24819 Comm: perf_fuzzer Not tainted 3.12.0 #4
> > [ 1618.224256] Hardware name: AOpen   DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BIOS 080015  10/19/2012
> > [ 1618.250825]  0000000000409000 ffff8800bf6dfaa8 ffffffff8151d8ec 0000000000000000
> > [ 1618.273081]  ffff8800c89ac928 ffff8800bf6dfaf8 ffffffff810ed692 dead000000200200
> > [ 1618.295345]  00000000c03df067 ffff8800bf6dfbe8 0000000000409000 ffffea0002bc2fe8
> > [ 1618.317603] Call Trace:
> > [ 1618.324951]  [<ffffffff8151d8ec>] dump_stack+0x49/0x5d
> > [ 1618.340355]  [<ffffffff810ed692>] print_bad_pte+0x1f5/0x213
> > [ 1618.357059]  [<ffffffff810ef43c>] unmap_single_vma+0x511/0x666
> > [ 1618.374540]  [<ffffffff810ef5c3>] unmap_vmas+0x32/0x49
> > [ 1618.389934]  [<ffffffff810f3804>] exit_mmap+0x84/0x10d
> > [ 1618.405343]  [<ffffffff8105bb15>] ? hrtimer_try_to_cancel+0x41/0x4b
> > [ 1618.424129]  [<ffffffff8103ac43>] mmput+0x4b/0xd1
> > [ 1618.438227]  [<ffffffff8103ec76>] do_exit+0x36c/0x936
> > [ 1618.453366]  [<ffffffff810c7312>] ? update_context_time+0x11/0x34
> > [ 1618.471628]  [<ffffffff8100951b>] ? native_sched_clock+0x3b/0x3d
> > [ 1618.489635]  [<ffffffff8106730d>] ? sched_clock_local+0x1c/0x82
> > [ 1618.507376]  [<ffffffff8103f2b8>] do_group_exit+0x78/0xa0
> > [ 1618.523563]  [<ffffffff8104c898>] get_signal_to_deliver+0x46d/0x48a
> > [ 1618.542347]  [<ffffffff810c8ac7>] ? ctx_sched_in+0x35/0x185
> > [ 1618.559051]  [<ffffffff810c8c80>] ? perf_event_sched_in+0x69/0x72
> > [ 1618.577318]  [<ffffffff81002513>] do_signal+0x46/0x5f5
> > [ 1618.592724]  [<ffffffff810c8ffe>] ? __perf_event_task_sched_in+0x3a/0x10e
> > [ 1618.613071]  [<ffffffff8106699f>] ? finish_task_switch+0x46/0x98
> > [ 1618.631075]  [<ffffffff8151f832>] ? __schedule+0x51c/0x54b
> > [ 1618.647516]  [<ffffffff81002aee>] do_notify_resume+0x2c/0x64
> > [ 1618.664486]  [<ffffffff81520ef5>] retint_signal+0x3d/0x78
> > [ 1618.680661] Disabling lock debugging due to kernel taint
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