lkml.org 
[lkml]   [2011]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] loop: queue_lock NULL pointer derefence in blk_throtl_exit (v2)
Performing
$ sudo mount -o loop -o umask=0 /dev/sdb1 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

$ sudo modprobe -r loop

results in oops:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
IP: [<ffffffff812479d4>] do_raw_spin_lock+0x14/0x122
Process modprobe (pid: 6189, threadinfo ffff88009a898000, task ffff880154a88000)
Call Trace:
[<ffffffff81486788>] _raw_spin_lock_irq+0x4a/0x51
[<ffffffff8123404b>] ? blk_throtl_exit+0x3b/0xa0
[<ffffffff8105b120>] ? cancel_delayed_work_sync+0xd/0xf
[<ffffffff8123404b>] blk_throtl_exit+0x3b/0xa0
[<ffffffff81229bc8>] blk_release_queue+0x21/0x65
[<ffffffff8123bb06>] kobject_release+0x51/0x66
[<ffffffff8123bab5>] ? kobject_release+0x0/0x66
[<ffffffff8123ce1e>] kref_put+0x43/0x4d
[<ffffffff8123ba27>] kobject_put+0x47/0x4b
[<ffffffff8122717c>] blk_cleanup_queue+0x56/0x5b
[<ffffffffa01c3824>] loop_exit+0x68/0x844 [loop]
[<ffffffff8107cccc>] sys_delete_module+0x1e8/0x25b
[<ffffffff814864c9>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81002112>] system_call_fastpath+0x16/0x1b


because of an attempt to acquire NULL queue_lock.
I added the same lines as in blk_queue_make_request -
`fall back to embedded per-queue lock'.

v2: According to comment by Vivek Goyal, queue_lock NULL check and fix moved
out from loop driver code to blk_cleanup_queue, which is more general approach.


Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

---

block/blk-core.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 2f4002f..45073ab 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -458,6 +458,10 @@ void blk_put_queue(struct request_queue *q)

void blk_cleanup_queue(struct request_queue *q)
{
+ /* fall back to our embedded per-queue locks */
+ if (!q->queue_lock)
+ q->queue_lock = &q->__queue_lock;
+
/*
* We know we have process context here, so we can be a little
* cautious and ensure that pending block actions on this device



\
 
 \ /
  Last update: 2011-01-20 14:01    [W:0.071 / U:2.016 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site