From 61bc84c4008812d784c398cfb54118c1ba396dfc Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 21 Mar 2022 19:03:24 -0600
Subject: [PATCH] io_uring: remove poll entry from list when canceling all
Git-commit: 61bc84c4008812d784c398cfb54118c1ba396dfc
Patch-mainline: v5.18-rc1
References: bsc#1205205
When the ring is exiting, as part of the shutdown, poll requests are
removed. But io_poll_remove_all() does not remove entries when finding
them, and since completions are done out-of-band, we can find and remove
the same entry multiple times.
We do guard the poll execution by poll ownership, but that does not
exclude us from reissuing a new one once the previous removal ownership
goes away.
This can race with poll execution as well, where we then end up seeing
req->apoll be NULL because a previous task_work requeue finished the
request.
Remove the poll entry when we find it and get ownership of it. This
prevents multiple invocations from finding it.
Fixes: aa43477b0402 ("io_uring: poll rework")
Reported-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
fs/io_uring.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 48f4540d7dd5..53bd71363a44 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6275,6 +6275,7 @@ static __cold bool io_poll_remove_all(struct io_ring_ctx *ctx,
list = &ctx->cancel_hash[i];
hlist_for_each_entry_safe(req, tmp, list, hash_node) {
if (io_match_task_safe(req, tsk, cancel_all)) {
+ hlist_del_init(&req->hash_node);
io_poll_cancel_req(req);
found = true;
}
--
2.35.3