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 <philipp.reisner@linbit.com>
CC: Lars Ellenberg <lars.ellenberg@linbit.com>
CC: "Christoph Böhmwalder" <christoph.boehmwalder@linbit.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Josef Bacik <josef@toxicpanda.com>
CC: Keith Busch <kbusch@kernel.org>
CC: Christoph Hellwig <hch@lst.de>
CC: Sagi Grimberg <sagi@grimberg.me>
CC: Lee Duncan <lduncan@suse.com>
CC: Chris Leech <cleech@redhat.com>
CC: Mike Christie <michael.christie@oracle.com>
CC: "James E.J. Bottomley" <jejb@linux.ibm.com>
CC: "Martin K. Petersen" <martin.petersen@oracle.com>
CC: Valentina Manea <valentina.manea.m@gmail.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: David Howells <dhowells@redhat.com>
CC: Marc Dionne <marc.dionne@auristor.com>
CC: Steve French <sfrench@samba.org>
CC: Christine Caulfield <ccaulfie@redhat.com>
CC: David Teigland <teigland@redhat.com>
CC: Mark Fasheh <mark@fasheh.com>
CC: Joel Becker <jlbec@evilplan.org>
CC: Joseph Qi <joseph.qi@linux.alibaba.com>
CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: Dominique Martinet <asmadeus@codewreck.org>
CC: Ilya Dryomov <idryomov@gmail.com>
CC: Xiubo Li <xiubli@redhat.com>
CC: Chuck Lever <chuck.lever@oracle.com>
CC: Jeff Layton <jlayton@kernel.org>
CC: Trond Myklebust <trond.myklebust@hammerspace.com>
CC: Anna Schumaker <anna@kernel.org>
CC: Steffen Klassert <steffen.klassert@secunet.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 4 insertions, 0 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e80252a83225..7bc7b5e03c51 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2944,6 +2944,7 @@ generic_ip_connect(struct TCP_Server_Info *server)
 		cifs_dbg(FYI, "Socket created\n");
 		server->ssocket = socket;
 		socket->sk->sk_allocation = GFP_NOFS;
+		socket->sk->sk_use_task_frag = false;
 		if (sfamily == AF_INET6)
 			cifs_reclassify_socket6(socket);
 		else
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);
 
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index 37d222bdfc8c..a07b24d170f2 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -1602,6 +1602,7 @@ static void o2net_start_connect(struct work_struct *work)
 	sc->sc_sock = sock; /* freed by sc_kref_release */
 
 	sock->sk->sk_allocation = GFP_ATOMIC;
+	sock->sk->sk_use_task_frag = false;
 
 	myaddr.sin_family = AF_INET;
 	myaddr.sin_addr.s_addr = mynode->nd_ipv4_address;