From: Al Viro <viro@ZenIV.linux.org.uk>
To: syzbot <syzbot+bacbe5d8791f30c9cee5@syzkaller.appspotmail.com>
Cc: akpm@linux-foundation.org, aneesh.kumar@linux.vnet.ibm.com,
dan.j.williams@intel.com, james.morse@arm.com,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, mingo@kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: possible deadlock in get_user_pages_unlocked
Date: Fri, 2 Feb 2018 04:50:20 +0000 [thread overview]
Message-ID: <20180202045020.GF30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <001a113f6344393d89056430347d@google.com>
On Thu, Feb 01, 2018 at 04:58:00PM -0800, syzbot wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> 7109a04eae81c41ed529da9f3c48c3655ccea741 (Thu Feb 1 17:37:30 2018 +0000)
> Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide
>
> So far this crash happened 2 times on upstream.
> C reproducer is attached.
Umm... How reproducible that is?
> syzkaller reproducer is attached.
> Raw console output is attached.
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached.
Can't reproduce with gcc 5.4.1 (same .config, same C reproducer).
It looks like __get_user_pages_locked() returning with *locked zeroed,
but ->mmap_sem not dropped. I don't see what could've lead to it and
attempts to reproduce had not succeeded so far...
How long does it normally take for lockdep splat to trigger?
next prev parent reply other threads:[~2018-02-02 4:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-02 0:58 possible deadlock in get_user_pages_unlocked syzbot
2018-02-02 4:50 ` Al Viro [this message]
2018-02-02 5:35 ` Eric Biggers
2018-02-02 5:46 ` Al Viro
2018-02-02 6:20 ` Al Viro
2018-02-02 8:57 ` Dmitry Vyukov
2018-02-10 1:36 ` Al Viro
2018-02-10 3:19 ` Eric Biggers
2018-03-10 4:15 ` Eric Biggers
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=20180202045020.GF30522@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=dan.j.williams@intel.com \
--cc=james.morse@arm.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@kernel.org \
--cc=syzbot+bacbe5d8791f30c9cee5@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.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