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* Re: possible deadlock in blk_trace_remove
       [not found] <001a1141f8dc4440a9055e53896e@google.com>
@ 2017-11-19 18:50 ` Jens Axboe
  2017-12-03 20:24 ` Eric Biggers
  1 sibling, 0 replies; 6+ messages in thread
From: Jens Axboe @ 2017-11-19 18:50 UTC (permalink / raw)
  To: syzbot, linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On 11/19/2017 03:36 AM, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on  
> d9e0e63d9a6f88440eb201e1491fcf730272c706
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> 
> Unfortunately, I don't have any reproducer for this bug yet.> 
> 
> Use struct sctp_sack_info instead
> 
> ============================================
> WARNING: possible recursive locking detected
> 4.14.0-rc8-next-20171110+ #40 Not tainted
> --------------------------------------------
> syz-executor6/21462 is trying to acquire lock:
>   (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81760261>]  
> blk_trace_remove+0x21/0x40 kernel/trace/blktrace.c:373
> 
> but task is already holding lock:
>   (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81763b38>]  
> blk_trace_setup+0x38/0x70 kernel/trace/blktrace.c:606
> 
> other info that might help us debug this:
>   Possible unsafe locking scenario:
> 
>         CPU0
>         ----
>    lock(&q->blk_trace_mutex);
>    lock(&q->blk_trace_mutex);

The below should fix it.


diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 206e0e2ace53..f224985de5fa 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -591,7 +591,7 @@ static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 		return ret;
 
 	if (copy_to_user(arg, &buts, sizeof(buts))) {
-		blk_trace_remove(q);
+		__blk_trace_remove(q);
 		return -EFAULT;
 	}
 	return 0;
@@ -637,7 +637,7 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
 		return ret;
 
 	if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
-		blk_trace_remove(q);
+		__blk_trace_remove(q);
 		return -EFAULT;
 	}
 
 
-- 
Jens Axboe

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: possible deadlock in blk_trace_remove
       [not found] <001a1141f8dc4440a9055e53896e@google.com>
  2017-11-19 18:50 ` possible deadlock in blk_trace_remove Jens Axboe
@ 2017-12-03 20:24 ` Eric Biggers
  2017-12-04  0:24   ` Jens Axboe
  1 sibling, 1 reply; 6+ messages in thread
From: Eric Biggers @ 2017-12-03 20:24 UTC (permalink / raw)
  To: syzbot; +Cc: axboe, linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On Sun, Nov 19, 2017 at 02:36:01AM -0800, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> d9e0e63d9a6f88440eb201e1491fcf730272c706
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> 
> Unfortunately, I don't have any reproducer for this bug yet.
> 
> 
> Use struct sctp_sack_info instead
> 
> ============================================
> WARNING: possible recursive locking detected
> 4.14.0-rc8-next-20171110+ #40 Not tainted
> --------------------------------------------
> syz-executor6/21462 is trying to acquire lock:
>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81760261>]
> blk_trace_remove+0x21/0x40 kernel/trace/blktrace.c:373
> 
> but task is already holding lock:
>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81763b38>]
> blk_trace_setup+0x38/0x70 kernel/trace/blktrace.c:606
> 
> other info that might help us debug this:
>  Possible unsafe locking scenario:

#syz fix: blktrace: fix trace mutex deadlock

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: possible deadlock in blk_trace_remove
  2017-12-03 20:24 ` Eric Biggers
@ 2017-12-04  0:24   ` Jens Axboe
  2017-12-04  0:44     ` Eric Biggers
  0 siblings, 1 reply; 6+ messages in thread
From: Jens Axboe @ 2017-12-04  0:24 UTC (permalink / raw)
  To: Eric Biggers, syzbot
  Cc: linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On 12/03/2017 01:24 PM, Eric Biggers wrote:
> On Sun, Nov 19, 2017 at 02:36:01AM -0800, syzbot wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> d9e0e63d9a6f88440eb201e1491fcf730272c706
>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>>
>> Unfortunately, I don't have any reproducer for this bug yet.
>>
>>
>> Use struct sctp_sack_info instead
>>
>> ============================================
>> WARNING: possible recursive locking detected
>> 4.14.0-rc8-next-20171110+ #40 Not tainted
>> --------------------------------------------
>> syz-executor6/21462 is trying to acquire lock:
>>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81760261>]
>> blk_trace_remove+0x21/0x40 kernel/trace/blktrace.c:373
>>
>> but task is already holding lock:
>>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81763b38>]
>> blk_trace_setup+0x38/0x70 kernel/trace/blktrace.c:606
>>
>> other info that might help us debug this:
>>  Possible unsafe locking scenario:
> 
> #syz fix: blktrace: fix trace mutex deadlock

This is fixed in current -git.

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: possible deadlock in blk_trace_remove
  2017-12-04  0:24   ` Jens Axboe
@ 2017-12-04  0:44     ` Eric Biggers
  2017-12-04  0:47       ` Jens Axboe
  0 siblings, 1 reply; 6+ messages in thread
From: Eric Biggers @ 2017-12-04  0:44 UTC (permalink / raw)
  To: Jens Axboe
  Cc: syzbot, linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On Sun, Dec 03, 2017 at 05:24:32PM -0700, Jens Axboe wrote:
> On 12/03/2017 01:24 PM, Eric Biggers wrote:
> > On Sun, Nov 19, 2017 at 02:36:01AM -0800, syzbot wrote:
> >> Hello,
> >>
> >> syzkaller hit the following crash on
> >> d9e0e63d9a6f88440eb201e1491fcf730272c706
> >> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> >> compiler: gcc (GCC) 7.1.1 20170620
> >> .config is attached
> >> Raw console output is attached.
> >>
> >> Unfortunately, I don't have any reproducer for this bug yet.
> >>
> >>
> >> Use struct sctp_sack_info instead
> >>
> >> ============================================
> >> WARNING: possible recursive locking detected
> >> 4.14.0-rc8-next-20171110+ #40 Not tainted
> >> --------------------------------------------
> >> syz-executor6/21462 is trying to acquire lock:
> >>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81760261>]
> >> blk_trace_remove+0x21/0x40 kernel/trace/blktrace.c:373
> >>
> >> but task is already holding lock:
> >>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81763b38>]
> >> blk_trace_setup+0x38/0x70 kernel/trace/blktrace.c:606
> >>
> >> other info that might help us debug this:
> >>  Possible unsafe locking scenario:
> > 
> > #syz fix: blktrace: fix trace mutex deadlock
> 
> This is fixed in current -git.
> 

I know, but syzbot needed to be told what commit fixes the bug.
See https://github.com/google/syzkaller/blob/master/docs/syzbot.md

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: possible deadlock in blk_trace_remove
  2017-12-04  0:44     ` Eric Biggers
@ 2017-12-04  0:47       ` Jens Axboe
  2017-12-04  3:47         ` Mike Galbraith
  0 siblings, 1 reply; 6+ messages in thread
From: Jens Axboe @ 2017-12-04  0:47 UTC (permalink / raw)
  To: Eric Biggers
  Cc: syzbot, linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On 12/03/2017 05:44 PM, Eric Biggers wrote:
> On Sun, Dec 03, 2017 at 05:24:32PM -0700, Jens Axboe wrote:
>> On 12/03/2017 01:24 PM, Eric Biggers wrote:
>>> On Sun, Nov 19, 2017 at 02:36:01AM -0800, syzbot wrote:
>>>> Hello,
>>>>
>>>> syzkaller hit the following crash on
>>>> d9e0e63d9a6f88440eb201e1491fcf730272c706
>>>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>>>> compiler: gcc (GCC) 7.1.1 20170620
>>>> .config is attached
>>>> Raw console output is attached.
>>>>
>>>> Unfortunately, I don't have any reproducer for this bug yet.
>>>>
>>>>
>>>> Use struct sctp_sack_info instead
>>>>
>>>> ============================================
>>>> WARNING: possible recursive locking detected
>>>> 4.14.0-rc8-next-20171110+ #40 Not tainted
>>>> --------------------------------------------
>>>> syz-executor6/21462 is trying to acquire lock:
>>>>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81760261>]
>>>> blk_trace_remove+0x21/0x40 kernel/trace/blktrace.c:373
>>>>
>>>> but task is already holding lock:
>>>>  (&q->blk_trace_mutex){+.+.}, at: [<ffffffff81763b38>]
>>>> blk_trace_setup+0x38/0x70 kernel/trace/blktrace.c:606
>>>>
>>>> other info that might help us debug this:
>>>>  Possible unsafe locking scenario:
>>>
>>> #syz fix: blktrace: fix trace mutex deadlock
>>
>> This is fixed in current -git.
>>
> 
> I know, but syzbot needed to be told what commit fixes the bug.
> See https://github.com/google/syzkaller/blob/master/docs/syzbot.md

Ah gotcha.

-- 
Jens Axboe

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: possible deadlock in blk_trace_remove
  2017-12-04  0:47       ` Jens Axboe
@ 2017-12-04  3:47         ` Mike Galbraith
  0 siblings, 0 replies; 6+ messages in thread
From: Mike Galbraith @ 2017-12-04  3:47 UTC (permalink / raw)
  To: Jens Axboe, Eric Biggers
  Cc: syzbot, linux-block, linux-kernel, mingo, rostedt, syzkaller-bugs

On Sun, 2017-12-03 at 17:47 -0700, Jens Axboe wrote:
> On 12/03/2017 05:44 PM, Eric Biggers wrote:
> > 
> >>> #syz fix: blktrace: fix trace mutex deadlock
> >>
> >> This is fixed in current -git.
> >>
> > 
> > I know, but syzbot needed to be told what commit fixes the bug.
> > See https://github.com/google/syzkaller/blob/master/docs/syzbot.md
> 
> Ah gotcha.

"@syzbot fix: bla" syntax would have been intuitive.

	-Mike

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-12-04  3:48 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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     [not found] <001a1141f8dc4440a9055e53896e@google.com>
2017-11-19 18:50 ` possible deadlock in blk_trace_remove Jens Axboe
2017-12-03 20:24 ` Eric Biggers
2017-12-04  0:24   ` Jens Axboe
2017-12-04  0:44     ` Eric Biggers
2017-12-04  0:47       ` Jens Axboe
2017-12-04  3:47         ` Mike Galbraith

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