Abaci reported the following warning:
[ 97.862205] ============================================
[ 97.863400] WARNING: possible recursive locking detected
[ 97.864640] 5.11.0-rc4+ #12 Not tainted
[ 97.865537] --------------------------------------------
[ 97.866748] a.out/2890 is trying to acquire lock:
[ 97.867829] ffff8881046763e8 (&ctx->uring_lock){+.+.}-{3:3}, at:
io_wq_submit_work+0x155/0x240
[ 97.869735]
[ 97.869735] but task is already holding lock:
[ 97.871033] ffff88810dfe0be8 (&ctx->uring_lock){+.+.}-{3:3}, at:
__x64_sys_io_uring_enter+0x3f0/0x5b0
[ 97.873074]
[ 97.873074] other info that might help us debug this:
[ 97.874520] Possible unsafe locking scenario:
[ 97.874520]
[ 97.875845] CPU0
[ 97.876440] ----
[ 97.877048] lock(&ctx->uring_lock);
[ 97.877961] lock(&ctx->uring_lock);
[ 97.878881]
[ 97.878881] *** DEADLOCK ***
[ 97.878881]
[ 97.880341] May be due to missing lock nesting notation
[ 97.880341]
[ 97.881952] 1 lock held by a.out/2890:
[ 97.882873] #0: ffff88810dfe0be8 (&ctx->uring_lock){+.+.}-{3:3}, at:
__x64_sys_io_uring_enter+0x3f0/0x5b0
[ 97.885108]
[ 97.885108] stack backtrace:
[ 97.886209] CPU: 0 PID: 2890 Comm: a.out Not tainted 5.11.0-rc4+ #12
[ 97.887683] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS
rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
[ 97.890457] Call Trace:
[ 97.891121] dump_stack+0xac/0xe3
[ 97.891972] __lock_acquire+0xab6/0x13a0
[ 97.892940] lock_acquire+0x2c3/0x390
[ 97.893853] ? io_wq_submit_work+0x155/0x240
[ 97.894894] __mutex_lock+0xae/0x9f0
[ 97.895785] ? io_wq_submit_work+0x155/0x240
[ 97.896816] ? __lock_acquire+0x782/0x13a0
[ 97.897817] ? io_wq_submit_work+0x155/0x240
[ 97.898867] ? io_wq_submit_work+0x155/0x240
[ 97.899916] ? _raw_spin_unlock_irqrestore+0x2d/0x40
[ 97.901101] io_wq_submit_work+0x155/0x240
[ 97.902112] io_wq_cancel_cb+0x162/0x490
[ 97.903084] ? io_uring_get_socket+0x40/0x40
[ 97.904126] io_async_find_and_cancel+0x3b/0x140
[ 97.905247] io_issue_sqe+0x86d/0x13e0
[ 97.906186] ? __lock_acquire+0x782/0x13a0
[ 97.907195] ? __io_queue_sqe+0x10b/0x550
[ 97.908175] ? lock_acquire+0x2c3/0x390
[ 97.909122] __io_queue_sqe+0x10b/0x550
[ 97.910080] ? io_req_prep+0xd8/0x1090
[ 97.911044] ? mark_held_locks+0x5a/0x80
[ 97.912042] ? mark_held_locks+0x5a/0x80
[ 97.913014] ? io_queue_sqe+0x235/0x470
[ 97.913971] io_queue_sqe+0x235/0x470
[ 97.914894] io_submit_sqes+0xcce/0xf10
[ 97.915842] ? xa_store+0x3b/0x50
[ 97.916683] ? __x64_sys_io_uring_enter+0x3f0/0x5b0
[ 97.917872] __x64_sys_io_uring_enter+0x3fb/0x5b0
[ 97.918995] ? lockdep_hardirqs_on_prepare+0xde/0x180
[ 97.920204] ? syscall_enter_from_user_mode+0x26/0x70
[ 97.921424] do_syscall_64+0x2d/0x40
[ 97.922329] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 97.923538] RIP: 0033:0x7f0b62601239
[ 97.924437] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00
48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f
05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 27 ec 2c 00 f7 d8 64 89 01
48
[ 97.928628] RSP: 002b:00007f0b62cc4d28 EFLAGS: 00000246 ORIG_RAX:
00000000000001aa
[ 97.930422] RAX: ffffffffffffffda RBX: 0000000000000000 RCX:
00007f0b62601239
[ 97.932073] RDX: 0000000000000000 RSI: 0000000000006cf6 RDI:
0000000000000005
[ 97.933710] RBP: 00007f0b62cc4e20 R08: 0000000000000000 R09:
0000000000000000
[ 97.935369] R10: 0000000000000000 R11: 0000000000000246 R12:
0000000000000000
[ 97.937008] R13: 0000000000021000 R14: 0000000000000000 R15:
00007f0b62cc5700
This is caused by try to hold uring_lock in io_wq_submit_work() without
checking if we are in io-wq thread context or not. It can be in original
context when io_wq_submit_work() is called from IORING_OP_ASYNC_CANCEL
code path, where we already held uring_lock.
Fixes: c07e6719511e ("io_uring: hold uring_lock while completing failed polled io in io_wq_submit_work()")
Reported-by: Abaci <abaci@xxxxxxxxxxxxxxxxx>
Signed-off-by: Hao Xu <haoxu@xxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 985a9e3f976d..15d0a96ec487 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6395,7 +6395,7 @@ static struct io_wq_work *io_wq_submit_work(struct io_wq_work *work)
if (ret) {
struct io_ring_ctx *lock_ctx = NULL;
- if (req->ctx->flags & IORING_SETUP_IOPOLL)
+ if ((req->ctx->flags & IORING_SETUP_IOPOLL) && io_wq_current_is_worker())
lock_ctx = req->ctx;
/*
--
1.8.3.1
