From: Tejun Heo <tj@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Hugh Dickins <hughd@google.com>,
Shaohua Li <shaohua.li@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH block/for-3.3/core] block: an exiting task should be allowed to create io_context
Date: Tue, 3 Jan 2012 14:13:01 -0800 [thread overview]
Message-ID: <20120103221301.GH31746@google.com> (raw)
In-Reply-To: <4F03631C.8080501@kernel.dk>
On Tue, Jan 03, 2012 at 09:20:44PM +0100, Jens Axboe wrote:
> On 2012-01-03 21:09, Tejun Heo wrote:
> > On Tue, Jan 03, 2012 at 09:59:22AM -0800, Tejun Heo wrote:
> >> That should have been service tree. I couldn't find more missing
> >> removals other than the one Shaohua's patch already fixed. Close
> >> cooperator selection in cfq_select_queue() seems suspicious tho. I
> >> can't see what prevents it from returning an empty coopeator cfqq.
> >> I'm trying to verify whether that's the case. Will update when I know
> >> more.
> >
> > While testing, found another bug.
> >
> > Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.
> > Last user: [<ffffffff813a82ee>](cfq_put_queue+0x7e/0xd0)
> > 070: e8 32 ab 1d 00 88 ff ff e8 32 ab 1d 00 88 ff ff .2.......2......
> > Prev obj: start=ffff88001dab3178, len=232
> > Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.
> > Last user: [<ffffffff813a82ee>](cfq_put_queue+0x7e/0xd0)
> > 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> > 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> > Next obj: start=ffff88001dab3378, len=232
> > Redzone: 0xd84156c5635688c0/0xd84156c5635688c0.
> > Last user: [<ffffffff813a8e53>](cfq_get_queue+0x153/0x670)
> > 000: 02 00 00 00 21 01 00 00 e0 c9 b1 1d 00 88 ff ff ....!...........
> > 010: 89 96 ae 18 00 88 ff ff 00 00 00 00 00 00 00 00 ................
> >
> > The field at 0x70 which is being updated after being freed is
> > cfqq->fifo. Interestingly, it didn't lead to any visible failure.
>
> That's pretty odd. Given Hughs report as well, it sure does sound like
> we now have some life time issues with cfqq's.
Hmmm... I disabled cfqq merge logic (commented out
cfq_close_cooperator() and the following cfq_setup_merge() calls) in
cfq_select_queue() and neither is triggering for quite a while now.
Maybe cfqq refcnt is getting borked over cfqq merging / splitting? It
would also explain the low frequency of the issue too. I'll try to
further isolate it but It would be awesome if someone more familiar
with the logic can go over that part.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-01-03 22:13 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20111221174733.9ba0861e762e8d96844b060b@canb.auug.org.au>
2011-12-21 23:15 ` linux-next: Tree for Dec 21 Andrew Morton
2011-12-22 23:08 ` Andrew Morton
2011-12-22 23:20 ` Tejun Heo
2011-12-22 23:24 ` Andrew Morton
2011-12-22 23:38 ` Tejun Heo
2011-12-22 23:44 ` Andrew Morton
2011-12-22 23:46 ` Tejun Heo
2011-12-23 0:42 ` Tejun Heo
2011-12-24 5:13 ` Hugh Dickins
2011-12-25 1:02 ` [PATCH block/for-3.3/core] block: an exiting task should be allowed to create io_context Tejun Heo
2011-12-25 13:29 ` Jens Axboe
2011-12-27 22:07 ` Andrew Morton
2011-12-28 8:33 ` Hugh Dickins
2011-12-28 16:48 ` Tejun Heo
2011-12-28 17:50 ` Hugh Dickins
2011-12-28 17:55 ` Tejun Heo
2011-12-28 21:19 ` Tejun Heo
2012-01-03 17:35 ` Tejun Heo
2012-01-03 17:59 ` Tejun Heo
2012-01-03 20:09 ` Tejun Heo
2012-01-03 20:20 ` Jens Axboe
2012-01-03 22:13 ` Tejun Heo [this message]
2012-01-03 22:35 ` Tejun Heo
2012-01-05 1:24 ` Tejun Heo
2012-01-05 18:36 ` Hugh Dickins
2012-01-05 18:38 ` Tejun Heo
2012-01-06 2:17 ` [PATCH block:for-3.3/core] cfq: merged request shouldn't jump to a different cfqq Tejun Heo
2012-01-06 2:36 ` Tejun Heo
2012-01-06 3:14 ` Shaohua Li
2012-01-06 3:04 ` Tejun Heo
2012-01-06 3:30 ` Tejun Heo
2012-01-06 3:52 ` [PATCH block:for-3.3/core] block: disable ELEVATOR_INSERT_SORT_MERGE Tejun Heo
2012-01-06 4:19 ` Shaohua Li
2012-01-06 4:38 ` Tejun Heo
2012-01-06 8:15 ` Shaohua Li
2012-01-06 15:34 ` Tejun Heo
2012-01-06 3:34 ` [PATCH block:for-3.3/core] cfq: merged request shouldn't jump to a different cfqq Shaohua Li
2012-01-06 3:22 ` Tejun Heo
2012-01-06 4:15 ` Shaohua Li
2012-01-06 4:40 ` Tejun Heo
2012-01-06 2:47 ` Shaohua Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120103221301.GH31746@google.com \
--to=tj@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=hughd@google.com \
--cc=linux-ide@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-next@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=sfr@canb.auug.org.au \
--cc=shaohua.li@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).