From: Chris Wright <chrisw@sous-sol.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>, CAI Qian <caiqian@redhat.com>,
Andrea Righi <andrea@betterlinux.com>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
Mel Gorman <mel@csn.ul.ie>, Izik Eidus <ieidus@redhat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [BUG 3.0.0-rc1] ksm: NULL pointer dereference in ksm_do_scan()
Date: Thu, 2 Jun 2011 08:36:41 -0700 [thread overview]
Message-ID: <20110602153641.GJ23047@sequoia.sous-sol.org> (raw)
In-Reply-To: <20110602143622.GE19505@random.random>
* Andrea Arcangeli (aarcange@redhat.com) wrote:
> On Thu, Jun 02, 2011 at 07:31:43AM -0700, Chris Wright wrote:
> > * CAI Qian (caiqian@redhat.com) wrote:
> > > madvise(0x2210000, 4096, 0xc /* MADV_??? */) = 0
> > > --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> >
> > Right, that's just what the program is trying to do, segfault.
> >
> > > +++ killed by SIGSEGV (core dumped) +++
> > > Segmentation fault (core dumped)
> > >
> > > Did I miss anything?
> >
> > I found it works but not 100% of the time.
> >
> > So I just run the bug in a loop.
>
> echo 0 >scan_millisecs helps.
BTW, here's my stack trace (I dropped back to 2.6.39 just to see if it
happened to be recent regression). It looks like mm_slot is off the list:
R10: dead000000200200 R11: dead000000100100
w/ ->mm == NULL. Smells like use after free, but doesn't quite all add up.
BUG: unable to handle kernel
ksmd-bug[14824]: segfault at 0 ip 0000000000400677 sp 00007fff987cb8b0 error 6 in ksmd-bug[400000+1000]
NULL pointer dereference at 0000000000000060
IP: [<ffffffff815be345>] down_read+0x19/0x28
PGD 0
Oops: 0002 [#1] SMP
last sysfs file: /sys/devices/system/cpu/cpu15/cache/index2/shared_cpu_map
CPU 6
Modules linked in: bridge stp vhost_net macvtap macvlan tun kvm_intel kvm ixgbe mdio igb [last unloaded: scsi_wait_scan]
Pid: 825, comm: ksmd Not tainted 2.6.39+ #23 Supermicro X8DTN/X8DTN
RIP: 0010:[<ffffffff815be345>] [<ffffffff815be345>] down_read+0x19/0x28
RSP: 0018:ffff8801b5325e10 EFLAGS: 00010246
RAX: 0000000000000060 RBX: 0000000000000060 RCX: 00000000ffffffff
RDX: 0000000000000000 RSI: 0000000000000286 RDI: 0000000000000060
RBP: ffff8801b5325e20 R08: ffffffffffffffff R09: ffff8801b5325db0
R10: dead000000200200 R11: dead000000100100 R12: 0000000000000000
R13: ffffffff81a20e60 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88033fc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000060 CR3: 0000000001a03000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process ksmd (pid: 825, threadinfo ffff8801b5324000, task ffff8801b55196b0)
Stack:
ffff8801b5325e20 0000000000000060 ffff8801b5325ee0 ffffffff810eec3a
ffff88033fd51cc0 ffff8801b5325e80 ffff8801b5325ee0 ffffffff00000000
ffff8801b55196b0 ffff8801b5325e98 ffff8801b5324000 00000064b5324010
Call Trace:
[<ffffffff810eec3a>] ksm_scan_thread+0x12d/0xc47
[<ffffffff8105a6e7>] ? wake_up_bit+0x2a/0x2a
[<ffffffff810eeb0d>] ? try_to_merge_with_ksm_page+0x498/0x498
[<ffffffff8105a25e>] kthread+0x82/0x8a
[<ffffffff815c6354>] kernel_thread_helper+0x4/0x10
[<ffffffff8105a1dc>] ? kthread_worker_fn+0x13f/0x13f
[<ffffffff815c6350>] ? gs_change+0xb/0xb
Code: 48 0f c1 10 48 85 d2 74 05 e8 98 84 c8 ff 58 5b c9 c3 55 48 89 e5 53 48 83 ec 08 0f 1f 44 00 00 48 89 fb e8 85 f4 ff ff 48 89 d8 <f0> 48 ff 00 79 05 e8 40 84 c8 ff 5a 5b c9 c3 55 48 89 e5 0f 1f
RIP [<ffffffff815be345>] down_read+0x19/0x28
RSP <ffff8801b5325e10>
CR2: 0000000000000060
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-06-02 15:37 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-01 22:20 Andrea Righi
2011-06-02 1:53 ` Chris Wright
2011-06-02 7:09 ` CAI Qian
2011-06-02 14:19 ` Andrea Righi
2011-06-02 16:48 ` Chris Wright
2011-06-02 17:29 ` Hugh Dickins
2011-06-02 17:43 ` Andrea Arcangeli
2011-06-03 17:06 ` Hugh Dickins
2011-06-03 18:13 ` Andrea Arcangeli
2011-06-02 17:35 ` [PATCH] ksm: fix race between ksmd and exiting task Chris Wright
2011-06-02 20:12 ` Andrea Righi
2011-06-02 21:23 ` Chris Wright
2011-06-03 16:37 ` Hugh Dickins
2011-06-04 0:54 ` [PATCH] ksm: fix NULL pointer dereference in scan_get_next_rmap_item Chris Wright
2011-06-02 20:10 ` [BUG 3.0.0-rc1] ksm: NULL pointer dereference in ksm_do_scan() Andrea Righi
2011-06-03 4:42 ` CAI Qian
2011-06-02 14:31 ` Chris Wright
2011-06-02 14:36 ` Andrea Arcangeli
2011-06-02 15:36 ` Chris Wright [this message]
2011-06-02 16:44 ` Andrea Arcangeli
2011-06-02 20:15 ` Andrea Righi
2011-06-02 21:35 ` Andrea Arcangeli
2011-06-03 4:50 ` CAI Qian
2011-06-03 4:44 ` CAI Qian
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=20110602153641.GJ23047@sequoia.sous-sol.org \
--to=chrisw@sous-sol.org \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=andrea@betterlinux.com \
--cc=caiqian@redhat.com \
--cc=hughd@google.com \
--cc=ieidus@redhat.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mel@csn.ul.ie \
--cc=riel@redhat.com \
/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