From 6b393a1ff1746a1c91bd95cbb2d79b104d8f15ac Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Sat, 16 Jan 2021 05:32:29 +0000
Subject: [PATCH] io_uring: fix false positive sqo warning on flush
WARNING: CPU: 1 PID: 9094 at fs/io_uring.c:8884
io_disable_sqo_submit+0x106/0x130 fs/io_uring.c:8884
Call Trace:
io_uring_flush+0x28b/0x3a0 fs/io_uring.c:9099
filp_close+0xb4/0x170 fs/open.c:1280
close_fd+0x5c/0x80 fs/file.c:626
__do_sys_close fs/open.c:1299 [inline]
__se_sys_close fs/open.c:1297 [inline]
__x64_sys_close+0x2f/0xa0 fs/open.c:1297
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
io_uring's final close() may be triggered by any task not only the
creator. It's well handled by io_uring_flush() including SQPOLL case,
though a warning in io_disable_sqo_submit() will fallaciously fire by
moving this warning out to the only call site that matters.
Reported-by: syzbot+2f5d1785dc624932da78@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5cda878b69cfd0..616c5f732a2691 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8918,8 +8918,6 @@ static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
static void io_disable_sqo_submit(struct io_ring_ctx *ctx)
{
- WARN_ON_ONCE(ctx->sqo_task != current);
-
mutex_lock(&ctx->uring_lock);
ctx->sqo_dead = 1;
mutex_unlock(&ctx->uring_lock);
@@ -8941,6 +8939,7 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
/* for SQPOLL only sqo_task has task notes */
+ WARN_ON_ONCE(ctx->sqo_task != current);
io_disable_sqo_submit(ctx);
task = ctx->sq_data->thread;
atomic_inc(&task->io_uring->in_idle);
--
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