From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <peterz@infradead.org>,
Daniel Wagner <wagi@monom.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [ANNOUNCE] v5.14-rc4-rt4
Date: Wed, 4 Aug 2021 17:47:43 +0200 [thread overview]
Message-ID: <20210804154743.niogqvnladdkfgi2@linutronix.de> (raw)
In-Reply-To: <f2d0a028-fe85-28ff-9cea-8ab1d26a15d0@kernel.dk>
On 2021-08-04 09:39:30 [-0600], Jens Axboe wrote:
> I'm confused, the waitqueue locks are always IRQ disabling.
spin_lock_irq() does not disable interrupts on -RT. The patch above
produces:
| BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35
| in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 2020, name: iou-wrk-2018
| 1 lock held by iou-wrk-2018/2020:
| #0: ffff888111a47de8 (&hash->wait){+.+.}-{0:0}, at: io_worker_handle_work+0x443/0x630
| irq event stamp: 10
| hardirqs last enabled at (9): [<ffffffff81c47818>] _raw_spin_unlock_irqrestore+0x28/0x70
| hardirqs last disabled at (10): [<ffffffff81c4769e>] _raw_spin_lock_irq+0x3e/0x40
| softirqs last enabled at (0): [<ffffffff81077238>] copy_process+0x8f8/0x2020
| softirqs last disabled at (0): [<0000000000000000>] 0x0
| CPU: 5 PID: 2020 Comm: iou-wrk-2018 Tainted: G W 5.14.0-rc4-rt4+ #97
| Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
| Call Trace:
| dump_stack_lvl+0x45/0x59
| ___might_sleep.cold+0xa6/0xb6
| rt_spin_lock+0x35/0xc0
| ? io_worker_handle_work+0x443/0x630
| io_worker_handle_work+0x443/0x630
| io_wqe_worker+0xb4/0x340
| ? lockdep_hardirqs_on_prepare+0xd4/0x170
| ? _raw_spin_unlock_irqrestore+0x28/0x70
| ? _raw_spin_unlock_irqrestore+0x28/0x70
| ? io_worker_handle_work+0x630/0x630
| ? rt_mutex_slowunlock+0x2ba/0x310
| ? io_worker_handle_work+0x630/0x630
| ret_from_fork+0x22/0x30
But indeed, you are right, my snippet breaks non-RT. So this then maybe:
diff --git a/fs/io-wq.c b/fs/io-wq.c
index 57d3cdddcdb3e..0b931ac3c83e6 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -384,7 +384,7 @@ static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
{
struct io_wq *wq = wqe->wq;
- spin_lock(&wq->hash->wait.lock);
+ spin_lock_irq(&wq->hash->wait.lock);
if (list_empty(&wqe->wait.entry)) {
__add_wait_queue(&wq->hash->wait, &wqe->wait);
if (!test_bit(hash, &wq->hash->map)) {
@@ -392,7 +392,7 @@ static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
list_del_init(&wqe->wait.entry);
}
}
- spin_unlock(&wq->hash->wait.lock);
+ spin_unlock_irq(&wq->hash->wait.lock);
}
static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
@@ -430,9 +430,9 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
}
if (stall_hash != -1U) {
- raw_spin_unlock(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
io_wait_on_hash(wqe, stall_hash);
- raw_spin_lock(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
}
return NULL;
(this is on-top of the patch you sent earlier and Daniel Cc: me on after
I checked that the problem/warning still exists).
Sebastian
next prev parent reply other threads:[~2021-08-04 15:47 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-02 16:27 [ANNOUNCE] v5.14-rc4-rt4 Sebastian Andrzej Siewior
2021-08-04 8:24 ` Daniel Wagner
2021-08-04 10:43 ` Sebastian Andrzej Siewior
2021-08-04 10:48 ` Sebastian Andrzej Siewior
2021-08-04 11:00 ` Sebastian Andrzej Siewior
2021-08-04 13:17 ` Peter Zijlstra
2021-08-04 13:32 ` Jens Axboe
2021-08-04 14:23 ` Jens Axboe
2021-08-04 15:33 ` Sebastian Andrzej Siewior
2021-08-04 15:39 ` Jens Axboe
2021-08-04 15:47 ` Sebastian Andrzej Siewior [this message]
2021-08-04 15:49 ` Jens Axboe
2021-08-04 15:57 ` Sebastian Andrzej Siewior
2021-08-04 16:05 ` Jens Axboe
2021-08-04 16:20 ` Sebastian Andrzej Siewior
2021-08-04 16:20 ` Jens Axboe
2021-08-04 16:20 ` Steven Rostedt
2021-08-04 16:22 ` Jens Axboe
2021-08-04 16:47 ` Sebastian Andrzej Siewior
2021-08-04 16:57 ` Jens Axboe
2021-08-04 17:02 ` Sebastian Andrzej Siewior
2021-08-10 7:40 ` Sebastian Andrzej Siewior
2021-08-10 11:22 ` [PATCH] io-wq: remove GFP_ATOMIC allocation off schedule out path kernel test robot
2021-08-10 15:22 ` kernel test robot
2021-08-04 16:17 ` [ANNOUNCE] v5.14-rc4-rt4 Steven Rostedt
2021-08-04 16:22 ` Sebastian Andrzej Siewior
2021-08-04 16:25 ` Steven Rostedt
2021-08-04 16:31 ` Sebastian Andrzej Siewior
2021-08-04 16:47 ` Steven Rostedt
2021-08-04 16:57 ` Sebastian Andrzej Siewior
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