public inbox for [email protected]
 help / color / mirror / Atom feed
From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 1/2] io_uring: fail cancellation for EXITING tasks
Date: Fri, 26 Nov 2021 14:38:14 +0000	[thread overview]
Message-ID: <4c41c5f379c6941ad5a07cd48cb66ed62199cf7e.1637937097.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

WARNING: CPU: 1 PID: 20 at fs/io_uring.c:6269 io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269
CPU: 1 PID: 20 Comm: kworker/1:0 Not tainted 5.16.0-rc1-syzkaller #0
Workqueue: events io_fallback_req_func
RIP: 0010:io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269
Call Trace:
 <TASK>
 io_req_task_link_timeout+0x6b/0x1e0 fs/io_uring.c:6886
 io_fallback_req_func+0xf9/0x1ae fs/io_uring.c:1334
 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445
 kthread+0x405/0x4f0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

We need original task's context to do cancellations, so if it's dying
and the callback is executed in a fallback mode, fail the cancellation
attempt.

Reported-by: [email protected]
Signed-off-by: Pavel Begunkov <[email protected]>
---
 fs/io_uring.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a4c508a1e0cf..7dd112d44adf 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6882,10 +6882,11 @@ static inline struct file *io_file_get(struct io_ring_ctx *ctx,
 static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
 {
 	struct io_kiocb *prev = req->timeout.prev;
-	int ret;
+	int ret = -ENOENT;
 
 	if (prev) {
-		ret = io_try_cancel_userdata(req, prev->user_data);
+		if (!(req->task->flags & PF_EXITING))
+			ret = io_try_cancel_userdata(req, prev->user_data);
 		io_req_complete_post(req, ret ?: -ETIME, 0);
 		io_put_req(prev);
 	} else {
-- 
2.34.0


  reply	other threads:[~2021-11-26 14:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-26 14:38 [PATCH 0/2] 5.16 fixes for syz reports Pavel Begunkov
2021-11-26 14:38 ` Pavel Begunkov [this message]
2021-11-26 15:32   ` [PATCH 1/2] io_uring: fail cancellation for EXITING tasks Pavel Begunkov
2021-11-26 14:38 ` [PATCH 2/2] io_uring: fix link traversal locking Pavel Begunkov
2021-11-26 15:29   ` Pavel Begunkov
2021-11-26 15:36 ` [PATCH 0/2] 5.16 fixes for syz reports Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4c41c5f379c6941ad5a07cd48cb66ed62199cf7e.1637937097.git.asml.silence@gmail.com \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox