From: Michal Hocko <mhocko@suse.cz>
To: Richard Weinberger <richard@nod.at>
Cc: LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
cgroups mailinglist <cgroups@vger.kernel.org>,
"kamezawa.hiroyu@jp.fujitsu.com" <kamezawa.hiroyu@jp.fujitsu.com>,
bsingharora@gmail.com, hannes@cmpxchg.org
Subject: Re: mem_cgroup_page_lruvec: BUG: unable to handle kernel NULL pointer dereference at 00000000000001a8
Date: Thu, 13 Jun 2013 15:29:08 +0200 [thread overview]
Message-ID: <20130613132908.GC23070@dhcp22.suse.cz> (raw)
In-Reply-To: <51B9B5BC.4090702@nod.at>
On Thu 13-06-13 14:06:20, Richard Weinberger wrote:
[...]
> All code
> ========
> 0: 89 50 08 mov %edx,0x8(%rax)
> 3: 48 89 d1 mov %rdx,%rcx
> 6: 0f 1f 40 00 nopl 0x0(%rax)
> a: 49 8b 04 24 mov (%r12),%rax
> e: 48 89 c2 mov %rax,%rdx
> 11: 48 c1 e8 38 shr $0x38,%rax
> 15: 83 e0 03 and $0x3,%eax
nid = page_to_nid
> 18: 48 c1 ea 3a shr $0x3a,%rdx
zid = page_zonenum
> 1c: 48 69 c0 38 01 00 00 imul $0x138,%rax,%rax
> 23: 48 03 84 d1 e0 02 00 add 0x2e0(%rcx,%rdx,8),%rax
&memcg->nodeinfo[nid]->zoneinfo[zid]
> 2a: 00
> 2b:* 48 3b 58 70 cmp 0x70(%rax),%rbx <-- trapping instruction
OK, so this maps to:
if (unlikely(lruvec->zone != zone)) <<<
lruvec->zone = zone;
> [35355.883056] RSP: 0000:ffff88003d523aa8 EFLAGS: 00010002
> [35355.883056] RAX: 0000000000000138 RBX: ffff88003fffa600 RCX: ffff88003e04a800
> [35355.883056] RDX: 0000000000000020 RSI: 0000000000000000 RDI: 0000000000028500
> [35355.883056] RBP: ffff88003d523ab8 R08: 0000000000000000 R09: 0000000000000000
> [35355.883056] R10: 0000000000000000 R11: dead000000100100 R12: ffffea0000a14000
> [35355.883056] R13: ffff88003e04b138 R14: ffff88003d523bb8 R15: ffffea0000a14020
> [35355.883056] FS: 0000000000000000(0000) GS:ffff88003fd80000(0000)
RAX (lruvec) is obviously incorrect and it doesn't make any sense. rax should
contain an address at an offset from ffff88003e04a800 But there is 0x138 there
instead.
Is this easily reproducible? Could you configure kdump.
--
Michal Hocko
SUSE Labs
--
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/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-06-13 13:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-13 11:48 richard -rw- weinberger
2013-06-13 12:02 ` Michal Hocko
2013-06-13 12:06 ` Richard Weinberger
2013-06-13 13:29 ` Michal Hocko [this message]
2013-06-13 13:32 ` Michal Hocko
2013-06-13 13:34 ` Richard Weinberger
2013-06-13 14:39 ` Michal Hocko
2013-06-13 14:45 ` Richard Weinberger
2013-06-13 14:57 ` Richard Weinberger
2013-06-13 15:19 ` Michal Hocko
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=20130613132908.GC23070@dhcp22.suse.cz \
--to=mhocko@suse.cz \
--cc=bsingharora@gmail.com \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=richard@nod.at \
/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