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From: Bart Van Assche <bvanassche@acm.org>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	linux-kernel@vger.kernel.org,
	syzbot <syzbot+6f39a9deb697359fe520@syzkaller.appspotmail.com>,
	syzkaller-bugs@googlegroups.com
Subject: Re: BUG: MAX_STACK_TRACE_ENTRIES too low! (2)
Date: Wed, 10 Jul 2019 10:46:00 -0700	[thread overview]
Message-ID: <f498d8cc-ba82-d3dc-7557-142a1b35976a@acm.org> (raw)
In-Reply-To: <20190710172123.GC801@sol.localdomain>

On 7/10/19 10:21 AM, Eric Biggers wrote:
> With my simplified reproducer, on commit 669de8bda87b ("kernel/workqueue: Use
> dynamic lockdep keys for workqueues") I see:
> 
> 	WARNING: CPU: 3 PID: 189 at kernel/locking/lockdep.c:747 register_lock_class+0x4f6/0x580
> 
> and then somewhat later:
> 
> 	BUG: MAX_LOCKDEP_KEYS too low!
> 
> If on top of that I cherry pick commit 28d49e282665 ("locking/lockdep: Shrink
> struct lock_class_key"), I see instead:
> 
> 	BUG: MAX_STACK_TRACE_ENTRIES too low!
> 
> I also see that on mainline.
> 
> Alternatively, if I check out 669de8bda87b and revert it, I don't see anything.

Hi Eric,

Is the rdma_ucm code the only code that triggers the "BUG:
MAX_STACK_TRACE_ENTRIES too low!" complaint or is this complaint also
triggered by other kernel code? I'm asking this because I think that
fixing this would require to implement garbage collection for the
stack_trace[] array in the lockdep code. That would make the lockdep
code slower. I don't think that making the lockdep code slower would be
welcome.

Bart.


  reply	other threads:[~2019-07-10 17:46 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-29 10:42 BUG: MAX_STACK_TRACE_ENTRIES too low! (2) syzbot
2019-03-30 11:10 ` syzbot
2019-03-30 21:58 ` syzbot
2019-03-31  2:17   ` Bart Van Assche
2019-07-10  5:30     ` Eric Biggers
2019-07-10 14:19       ` Bart Van Assche
2019-07-10 17:00         ` Eric Biggers
2019-07-10 17:21           ` Eric Biggers
2019-07-10 17:46             ` Bart Van Assche [this message]
2019-07-10 18:02               ` Eric Biggers
2019-07-10 18:36                 ` Bart Van Assche
2019-07-10 18:44                   ` Eric Dumazet
2019-07-10 19:09                     ` Bart Van Assche
2019-07-10 20:47                       ` Eric Dumazet
2019-07-10 21:23                         ` Bart Van Assche
2019-07-10 22:09                           ` Peter Zijlstra
2019-07-11 18:53                             ` Bart Van Assche
2019-07-12  8:55                               ` Peter Zijlstra
2019-07-12 23:03                                 ` Bart Van Assche

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