From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: Dmitry Vyukov <dvyukov@google.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Jens Axboe <axboe@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: mm: GPF in bdi_put
Date: Thu, 2 Mar 2017 11:44:53 +0000 [thread overview]
Message-ID: <20170302114453.GX29622@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170301142909.GG20512@quack2.suse.cz>
On Wed, Mar 01, 2017 at 03:29:09PM +0100, Jan Kara wrote:
> The problem is writeback code (from flusher work or through sync(2) -
> generally inode_to_bdi() users) can be looking at bdev inode independently
> from it being open. So if they start looking while the bdev is open but the
> dereference happens after it is closed and device removed, we oops. We have
> seen oopses due to this for quite a while. And all the stuff that is done
> in __blkdev_put() is not enough to prevent writeback code from having a
> look whether there is not something to write.
Um. What's to prevent the queue/device/module itself from disappearing
from under you? IOW, what are you doing that is safe to do in face of
driver going rmmoded?
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WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: Dmitry Vyukov <dvyukov@google.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, Jens Axboe <axboe@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: mm: GPF in bdi_put
Date: Thu, 2 Mar 2017 11:44:53 +0000 [thread overview]
Message-ID: <20170302114453.GX29622@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170301142909.GG20512@quack2.suse.cz>
On Wed, Mar 01, 2017 at 03:29:09PM +0100, Jan Kara wrote:
> The problem is writeback code (from flusher work or through sync(2) -
> generally inode_to_bdi() users) can be looking at bdev inode independently
> from it being open. So if they start looking while the bdev is open but the
> dereference happens after it is closed and device removed, we oops. We have
> seen oopses due to this for quite a while. And all the stuff that is done
> in __blkdev_put() is not enough to prevent writeback code from having a
> look whether there is not something to write.
Um. What's to prevent the queue/device/module itself from disappearing
from under you? IOW, what are you doing that is safe to do in face of
driver going rmmoded?
next prev parent reply other threads:[~2017-03-02 11:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-27 17:11 mm: GPF in bdi_put Dmitry Vyukov
2017-02-27 17:11 ` Dmitry Vyukov
2017-02-27 17:14 ` Dmitry Vyukov
2017-02-27 17:14 ` Dmitry Vyukov
2017-02-27 18:27 ` Al Viro
2017-02-27 18:27 ` Al Viro
2017-02-28 17:55 ` Dmitry Vyukov
2017-02-28 17:55 ` Dmitry Vyukov
2017-02-28 18:23 ` Al Viro
2017-02-28 18:23 ` Al Viro
2017-03-01 14:29 ` Jan Kara
2017-03-01 14:29 ` Jan Kara
2017-03-01 15:05 ` Jan Kara
2017-03-01 15:05 ` Jan Kara
2017-03-02 11:44 ` Al Viro [this message]
2017-03-02 11:44 ` Al Viro
2017-03-02 12:20 ` Jan Kara
2017-03-02 12:20 ` Jan Kara
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