The patch below does not apply to the 5.11-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 9ae1f8dd372e0e4c020b345cf9e09f519265e981 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov asml.silence@gmail.com Date: Mon, 1 Feb 2021 18:59:51 +0000 Subject: [PATCH] io_uring: fix inconsistent lock state
WARNING: inconsistent lock state
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. syz-executor217/8450 [HC1[1]:SC0[0]:HE0:SE1] takes: ffff888023d6e620 (&fs->lock){?.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff888023d6e620 (&fs->lock){?.+.}-{2:2}, at: io_req_clean_work fs/io_uring.c:1398 [inline] ffff888023d6e620 (&fs->lock){?.+.}-{2:2}, at: io_dismantle_req+0x66f/0xf60 fs/io_uring.c:2029
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&fs->lock); <Interrupt> lock(&fs->lock);
*** DEADLOCK ***
1 lock held by syz-executor217/8450: #0: ffff88802417c3e8 (&ctx->uring_lock){+.+.}-{3:3}, at: __do_sys_io_uring_enter+0x1071/0x1f30 fs/io_uring.c:9442
stack backtrace: CPU: 1 PID: 8450 Comm: syz-executor217 Not tainted 5.11.0-rc5-next-20210129-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> [...] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] io_req_clean_work fs/io_uring.c:1398 [inline] io_dismantle_req+0x66f/0xf60 fs/io_uring.c:2029 __io_free_req+0x3d/0x2e0 fs/io_uring.c:2046 io_free_req fs/io_uring.c:2269 [inline] io_double_put_req fs/io_uring.c:2392 [inline] io_put_req+0xf9/0x570 fs/io_uring.c:2388 io_link_timeout_fn+0x30c/0x480 fs/io_uring.c:6497 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x609/0xe40 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xbd/0x100 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:199 spin_unlock_irq include/linux/spinlock.h:404 [inline] io_queue_linked_timeout+0x194/0x1f0 fs/io_uring.c:6525 __io_queue_sqe+0x328/0x1290 fs/io_uring.c:6594 io_queue_sqe+0x631/0x10d0 fs/io_uring.c:6639 io_queue_link_head fs/io_uring.c:6650 [inline] io_submit_sqe fs/io_uring.c:6697 [inline] io_submit_sqes+0x19b5/0x2720 fs/io_uring.c:6960 __do_sys_io_uring_enter+0x107d/0x1f30 fs/io_uring.c:9443 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Don't free requests from under hrtimer context (softirq) as it may sleep or take spinlocks improperly (e.g. non-irq versions).
Cc: stable@vger.kernel.org # 5.6+ Reported-by: syzbot+81d17233a2b02eafba33@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/fs/io_uring.c b/fs/io_uring.c index 6711200ece22..1310c074f4cc 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1886,8 +1886,8 @@ static void io_cqring_fill_event(struct io_kiocb *req, long res) __io_cqring_fill_event(req, res, 0); }
-static void io_req_complete_nostate(struct io_kiocb *req, long res, - unsigned int cflags) +static void io_req_complete_post(struct io_kiocb *req, long res, + unsigned int cflags) { struct io_ring_ctx *ctx = req->ctx; unsigned long flags; @@ -1898,6 +1898,12 @@ static void io_req_complete_nostate(struct io_kiocb *req, long res, spin_unlock_irqrestore(&ctx->completion_lock, flags);
io_cqring_ev_posted(ctx); +} + +static inline void io_req_complete_nostate(struct io_kiocb *req, long res, + unsigned int cflags) +{ + io_req_complete_post(req, res, cflags); io_put_req(req); }
@@ -6489,9 +6495,10 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) if (prev) { req_set_fail_links(prev); io_async_find_and_cancel(ctx, req, prev->user_data, -ETIME); - io_put_req(prev); + io_put_req_deferred(prev, 1); } else { - io_req_complete(req, -ETIME); + io_req_complete_post(req, -ETIME, 0); + io_put_req_deferred(req, 1); } return HRTIMER_NORESTART; }