From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
toke@redhat.com
Subject: Re: [PATCH net-next] net: Add lockdep asserts to ____napi_schedule().
Date: Thu, 17 Mar 2022 19:48:51 -0600 [thread overview]
Message-ID: <YjPlAyly8FQhPJjT@zx2c4.com> (raw)
In-Reply-To: <YitkzkjU5zng7jAM@linutronix.de>
Hi Sebastian,
On Fri, Mar 11, 2022 at 04:03:42PM +0100, Sebastian Andrzej Siewior wrote:
> ____napi_schedule() needs to be invoked with disabled interrupts due to
> __raise_softirq_irqoff (in order not to corrupt the per-CPU list).
> ____napi_schedule() needs also to be invoked from an interrupt context
> so that the raised-softirq is processed while the interrupt context is
> left.
>
> Add lockdep asserts for both conditions.
> While this is the second time the irq/softirq check is needed, provide a
> generic lockdep_assert_softirq_will_run() which is used by both caller.
I stumbled upon this commit when noticing a new failure in WireGuard's
test suite:
[ 1.338823] ------------[ cut here ]------------
[ 1.339289] WARNING: CPU: 0 PID: 11 at ../../../../../../../../net/core/dev.c:4268 __napi_schedule+0xa1/0x300
[ 1.340222] CPU: 0 PID: 11 Comm: kworker/0:1 Not tainted 5.17.0-rc8-debug+ #1
[ 1.340896] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS d55cb5a 04/01/2014
[ 1.341669] Workqueue: wg-crypt-wg0 wg_packet_decrypt_worker
[ 1.342207] RIP: 0010:__napi_schedule+0xa1/0x300
[ 1.342655] Code: c0 03 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 eb 01 00 00 8b 05 cd a9 0d 01 85 c0 74 1f 65 8b 05 d6 87 7d 7e a9 00 ff 0f 00 75 02 <0f> 0b 65 8b 05 96 8e 7d 7e 85 c0 0f 84 86 01 00 00 4c 8d 73 10 be
[ 1.344366] RSP: 0018:ffff888004bc7c98 EFLAGS: 00010046
[ 1.344861] RAX: 0000000080000000 RBX: ffff888007570750 RCX: 1ffffffff05251e5
[ 1.345532] RDX: 0000000000000000 RSI: ffffffff822e1060 RDI: ffffffff8244c700
[ 1.346189] RBP: ffff888036400000 R08: 0000000000000001 R09: ffff888007570767
[ 1.346847] R10: ffffed1000eae0ec R11: 0000000000000001 R12: 0000000000000200
[ 1.347504] R13: 00000000000364c0 R14: ffff8880078231c0 R15: ffff888007570750
[ 1.348193] FS: 0000000000000000(0000) GS:ffff888036400000(0000) knlGS:0000000000000000
[ 1.348973] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1.349505] CR2: 00007ffec7b8ed3c CR3: 0000000002625005 CR4: 0000000000370eb0
[ 1.350207] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1.350921] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1.351587] Call Trace:
[ 1.351822] <TASK>
[ 1.352026] ? napi_schedule_prep+0x37/0x90
[ 1.352417] wg_packet_decrypt_worker+0x2ac/0x470
[ 1.352859] ? lock_is_held_type+0xd7/0x130
[ 1.353251] process_one_work+0x839/0x1380
[ 1.353651] ? rcu_read_unlock+0x40/0x40
[ 1.354023] ? pwq_dec_nr_in_flight+0x230/0x230
[ 1.354448] ? __rwlock_init+0x140/0x140
[ 1.354826] worker_thread+0x593/0xf60
[ 1.355180] ? process_one_work+0x1380/0x1380
[ 1.355593] ? process_one_work+0x1380/0x1380
[ 1.356002] kthread+0x262/0x300
[ 1.356308] ? kthread_exit+0xc0/0xc0
[ 1.356656] ret_from_fork+0x1f/0x30
[ 1.357011] </TASK>
Sounds like wg_packet_decrypt_worker() might be doing something wrong? I
vaguely recall a thread where you started looking into some things there
that seemed non-optimal, but I didn't realize there were correctness
issues. If your patch is correct, and wg_packet_decrypt_worker() is
wrong, do you have a concrete idea of how we should approach fixing
wireguard? Or do you want to send a patch for that?
Jason
next prev parent reply other threads:[~2022-03-18 1:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 15:03 [PATCH net-next] net: Add lockdep asserts to ____napi_schedule() Sebastian Andrzej Siewior
2022-03-14 10:40 ` patchwork-bot+netdevbpf
2022-03-17 19:21 ` Saeed Mahameed
2022-03-18 10:05 ` Sebastian Andrzej Siewior
2022-03-18 1:48 ` Jason A. Donenfeld [this message]
2022-03-18 10:57 ` Sebastian Andrzej Siewior
2022-03-18 18:19 ` Jason A. Donenfeld
2022-03-18 18:59 ` Jakub Kicinski
2022-03-19 0:41 ` Jason A. Donenfeld
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