Treewide: Stop corrupting socket's task_frag

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 <[email protected]>
CC: Lars Ellenberg <[email protected]>
CC: "Christoph Böhmwalder" <[email protected]>
CC: Jens Axboe <[email protected]>
CC: Josef Bacik <[email protected]>
CC: Keith Busch <[email protected]>
CC: Christoph Hellwig <[email protected]>
CC: Sagi Grimberg <[email protected]>
CC: Lee Duncan <[email protected]>
CC: Chris Leech <[email protected]>
CC: Mike Christie <[email protected]>
CC: "James E.J. Bottomley" <[email protected]>
CC: "Martin K. Petersen" <[email protected]>
CC: Valentina Manea <[email protected]>
CC: Shuah Khan <[email protected]>
CC: Greg Kroah-Hartman <[email protected]>
CC: David Howells <[email protected]>
CC: Marc Dionne <[email protected]>
CC: Steve French <[email protected]>
CC: Christine Caulfield <[email protected]>
CC: David Teigland <[email protected]>
CC: Mark Fasheh <[email protected]>
CC: Joel Becker <[email protected]>
CC: Joseph Qi <[email protected]>
CC: Eric Van Hensbergen <[email protected]>
CC: Latchesar Ionkov <[email protected]>
CC: Dominique Martinet <[email protected]>
CC: Ilya Dryomov <[email protected]>
CC: Xiubo Li <[email protected]>
CC: Chuck Lever <[email protected]>
CC: Jeff Layton <[email protected]>
CC: Trond Myklebust <[email protected]>
CC: Anna Schumaker <[email protected]>
CC: Steffen Klassert <[email protected]>
CC: Herbert Xu <[email protected]>

Suggested-by: Guillaume Nault <[email protected]>
Signed-off-by: Benjamin Coddington <[email protected]>
Reviewed-by: Guillaume Nault <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 8b80ca0cd65f..4450721ec83c 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -645,6 +645,7 @@ static void add_sock(struct socket *sock, struct connection *con)
 	if (dlm_config.ci_protocol == DLM_PROTO_SCTP)
 		sk->sk_state_change = lowcomms_state_change;
 	sk->sk_allocation = GFP_NOFS;
+	sk->sk_use_task_frag = false;
 	sk->sk_error_report = lowcomms_error_report;
 	release_sock(sk);
 }
@@ -1769,6 +1770,7 @@ static int dlm_listen_for_all(void)
 	listen_con.sock = sock;
 
 	sock->sk->sk_allocation = GFP_NOFS;
+	sock->sk->sk_use_task_frag = false;
 	sock->sk->sk_data_ready = lowcomms_listen_data_ready;
 	release_sock(sock->sk);