From 98123866fcf3fe95a0c1b198ef122dfdbd351916 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Fri, 16 Dec 2022 07:45:27 -0500 Subject: Treewide: Stop corrupting socket's task_frag MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since moving to memalloc_nofs_save/restore, SUNRPC has stopped setting the GFP_NOIO flag on sk_allocation which the networking system uses to decide when it is safe to use current->task_frag. The results of this are unexpected corruption in task_frag when SUNRPC is involved in memory reclaim. The corruption can be seen in crashes, but the root cause is often difficult to ascertain as a crashing machine's stack trace will have no evidence of being near NFS or SUNRPC code. I believe this problem to be much more pervasive than reports to the community may indicate. Fix this by having kernel users of sockets that may corrupt task_frag due to reclaim set sk_use_task_frag = false. Preemptively correcting this situation for users that still set sk_allocation allows them to convert to memalloc_nofs_save/restore without the same unexpected corruptions that are sure to follow, unlikely to show up in testing, and difficult to bisect. CC: Philipp Reisner CC: Lars Ellenberg CC: "Christoph Böhmwalder" CC: Jens Axboe CC: Josef Bacik CC: Keith Busch CC: Christoph Hellwig CC: Sagi Grimberg CC: Lee Duncan CC: Chris Leech CC: Mike Christie CC: "James E.J. Bottomley" CC: "Martin K. Petersen" CC: Valentina Manea CC: Shuah Khan CC: Greg Kroah-Hartman CC: David Howells CC: Marc Dionne CC: Steve French CC: Christine Caulfield CC: David Teigland CC: Mark Fasheh CC: Joel Becker CC: Joseph Qi CC: Eric Van Hensbergen CC: Latchesar Ionkov CC: Dominique Martinet CC: Ilya Dryomov CC: Xiubo Li CC: Chuck Lever CC: Jeff Layton CC: Trond Myklebust CC: Anna Schumaker CC: Steffen Klassert CC: Herbert Xu Suggested-by: Guillaume Nault Signed-off-by: Benjamin Coddington Reviewed-by: Guillaume Nault Signed-off-by: Jakub Kicinski --- net/9p/trans_fd.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/9p') diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 07db2f436d44..d9120f14684b 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -868,6 +868,7 @@ static int p9_socket_open(struct p9_client *client, struct socket *csocket) } csocket->sk->sk_allocation = GFP_NOIO; + csocket->sk->sk_use_task_frag = false; file = sock_alloc_file(csocket, 0, NULL); if (IS_ERR(file)) { pr_err("%s (%d): failed to map fd\n", -- cgit