6.1-stable review patch. If anyone has any objections, please let me know.
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From: Fiona Ebner f.ebner@proxmox.com
[ Upstream commit 00be6f26a2a7c671f1402d74c4d3c30a5844660a ]
When io_uring is used in the same task as CIFS, there might be unnecessary reconnects, causing issues in user-space applications like QEMU with a log like:
CIFS: VFS: \10.10.100.81 Error -512 sending data on socket to server
Certain io_uring completions might be added to task_work with notify_method being TWA_SIGNAL and thus TIF_NOTIFY_SIGNAL is set for the task.
In __smb_send_rqst(), signals are masked before calling smb_send_kvec(), but the masking does not apply to TIF_NOTIFY_SIGNAL.
If sk_stream_wait_memory() is reached via sock_sendmsg() while TIF_NOTIFY_SIGNAL is set, signal_pending(current) will evaluate to true there, and -EINTR will be propagated all the way from sk_stream_wait_memory() to sock_sendmsg() in smb_send_kvec(). Afterwards, __smb_send_rqst() will see that not everything was written and reconnect.
Signed-off-by: Fiona Ebner f.ebner@proxmox.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/transport.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c index d2867bd263c55..8a0342bb3ebe7 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -22,6 +22,7 @@ #include <linux/mempool.h> #include <linux/sched/signal.h> #include <linux/task_io_accounting_ops.h> +#include <linux/task_work.h> #include "cifspdu.h" #include "cifsglob.h" #include "cifsproto.h" @@ -211,9 +212,16 @@ smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg, * send a packet. In most cases if we fail to send * after the retries we will kill the socket and * reconnect which may clear the network problem. + * + * Even if regular signals are masked, EINTR might be + * propagated from sk_stream_wait_memory() to here when + * TIF_NOTIFY_SIGNAL is used for task work. For example, + * certain io_uring completions will use that. Treat + * having EINTR with pending task work the same as EAGAIN + * to avoid unnecessary reconnects. */ rc = sock_sendmsg(ssocket, smb_msg); - if (rc == -EAGAIN) { + if (rc == -EAGAIN || unlikely(rc == -EINTR && task_work_pending(current))) { retries++; if (retries >= 14 || (!server->noblocksnd && (retries > 2))) {