Re: [syzbot] [fs?] [mm?] INFO: task hung in v9fs_file_fsync

[Oleg Nesterov <oleg@redhat.com>]

On 08/18, syzbot wrote:
>
> Hello,
>
> syzbot has tested the proposed patch and the reproducer did not trigger any issue:
>
> Reported-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
> Tested-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
>
> Tested on:
>
> commit:         038d61fd Linux 6.16

And trans_fd.c wasn't changed since 038d61fd...

Dominique, David,

Perhaps you can reconsider the fix that Prateek and I tried to propose
in this thread

	[syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter
	https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@google.com/

Oleg.
---

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 339ec4e54778..474fe67f72ac 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -666,7 +666,6 @@ static void p9_poll_mux(struct p9_conn *m)
 
 static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
 {
-	__poll_t n;
 	int err;
 	struct p9_trans_fd *ts = client->trans;
 	struct p9_conn *m = &ts->conn;
@@ -686,13 +685,7 @@ static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
 	list_add_tail(&req->req_list, &m->unsent_req_list);
 	spin_unlock(&m->req_lock);
 
-	if (test_and_clear_bit(Wpending, &m->wsched))
-		n = EPOLLOUT;
-	else
-		n = p9_fd_poll(m->client, NULL, NULL);
-
-	if (n & EPOLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
-		schedule_work(&m->wq);
+	p9_poll_mux(m);
 
 	return 0;
 }