From: Ido Schimmel <idosch@nvidia.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: syzbot <syzbot+3384541342de0ca933f1@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [syzbot] [kernel?] possible deadlock in __hrtimer_run_queues
Date: Sat, 13 May 2023 12:37:28 +0300 [thread overview]
Message-ID: <ZF9aWEeQ5+Xvc+oF@shredder> (raw)
In-Reply-To: <871qjldbes.ffs@tglx>
On Fri, May 12, 2023 at 01:41:47PM +0200, Thomas Gleixner wrote:
> No problem. The lockdep splat is enough data.
>
> Fix below.
Thomas, I applied the fix on top of net-next (which includes
0af462f19e63). I'm getting the splat below during boot and then the
systems hangs.
Thanks
[ 1.708425] ============================================
[ 1.709253] WARNING: possible recursive locking detected
[ 1.710079] 6.4.0-rc1-custom-gba79e9a73284-dirty #52 Not tainted
[ 1.711016] --------------------------------------------
[ 1.711842] swapper/0/0 is trying to acquire lock:
[ 1.712593] ffffffff8863bfb0 (&obj_hash[i].lock){....}-{2:2}, at: debug_object_activate+0x149/0x560
[ 1.714037]
[ 1.714037] but task is already holding lock:
[ 1.714947] ffffffff8863bfb0 (&obj_hash[i].lock){....}-{2:2}, at: debug_object_assert_init+0x279/0x410
[ 1.716411]
[ 1.716411] other info that might help us debug this:
[ 1.717419] Possible unsafe locking scenario:
[ 1.717419]
[ 1.718332] CPU0
[ 1.718716] ----
[ 1.719099] lock(&obj_hash[i].lock);
[ 1.719695] lock(&obj_hash[i].lock);
[ 1.720282]
[ 1.720282] *** DEADLOCK ***
[ 1.720282]
[ 1.721195] May be due to missing lock nesting notation
[ 1.721195]
[ 1.722245] 2 locks held by swapper/0/0:
[ 1.722861] #0: ffffffff8863bfb0 (&obj_hash[i].lock){....}-{2:2}, at: debug_object_assert_init+0x279/0x410
[ 1.724393] #1: ffff8881f61e9618 (&base->lock){....}-{2:2}, at: lock_timer_base+0x5f/0x200
[ 1.725718]
[ 1.725718] stack backtrace:
[ 1.726396] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.4.0-rc1-custom-gba79e9a73284-dirty #52
[ 1.727737] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc37 04/01/2014
[ 1.729091] Call Trace:
[ 1.729473] <TASK>
[ 1.729816] dump_stack_lvl+0x91/0xf0
[ 1.730400] check_deadlock+0x618/0xb10
[ 1.731023] __lock_acquire+0x2226/0x62d0
[ 1.731664] ? lockdep_hardirqs_on_prepare+0x420/0x420
[ 1.732475] lock_acquire+0x1a7/0x4e0
[ 1.733057] ? debug_object_activate+0x149/0x560
[ 1.733791] ? lock_sync+0x180/0x180
[ 1.734354] ? lock_acquired+0x238/0xa30
[ 1.735000] ? lock_acquire+0x1a7/0x4e0
[ 1.735613] ? find_held_lock+0x34/0x110
[ 1.736238] _raw_spin_lock_irqsave+0x46/0x90
[ 1.736936] ? debug_object_activate+0x149/0x560
[ 1.737669] debug_object_activate+0x149/0x560
[ 1.738372] ? debug_object_destroy+0x210/0x210
[ 1.739095] ? _raw_spin_lock_irqsave+0x60/0x90
[ 1.739820] ? lock_timer_base+0x184/0x200
[ 1.740469] __mod_timer+0x820/0xea0
[ 1.741047] ? timer_fixup_activate+0x2c0/0x2c0
[ 1.741770] ? find_held_lock+0x34/0x110
[ 1.742397] ? lock_release+0x3b5/0xbd0
[ 1.743013] add_timer+0x67/0x90
[ 1.743528] __queue_delayed_work+0x1a2/0x270
[ 1.744226] queue_delayed_work_on+0xce/0xd0
[ 1.744912] crng_reseed+0x124/0x270
[ 1.745485] ? random_write_iter+0x20/0x20
[ 1.746137] ? add_device_randomness+0xbd/0xf0
[ 1.746851] ? blake2s_update+0x106/0x4e0
[ 1.747492] random_init+0xcd/0x1a0
[ 1.748054] ? random_init_early+0x2a0/0x2a0
[ 1.748739] ? hrtimers_prepare_cpu+0xab/0x330
[ 1.749446] start_kernel+0x226/0x520
[ 1.750039] x86_64_start_reservations+0x18/0x30
[ 1.750776] x86_64_start_kernel+0xf4/0x150
[ 1.751432] secondary_startup_64_no_verify+0x106/0x10b
[ 1.752264] </TASK>
next prev parent reply other threads:[~2023-05-13 9:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-12 5:55 [syzbot] [kernel?] possible deadlock in __hrtimer_run_queues syzbot
2023-05-12 11:41 ` Thomas Gleixner
2023-05-13 9:37 ` Ido Schimmel [this message]
2023-05-13 19:34 ` Thomas Gleixner
2023-05-14 6:48 ` Ido Schimmel
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