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authorChuck Lever <chuck.lever@oracle.com>2024-04-03 10:36:25 -0400
committerChuck Lever <chuck.lever@oracle.com>2024-04-04 09:43:02 -0400
commit05258a0a69b3c5d2c003f818702c0a52b6fea861 (patch)
treec76a5d2475d8a7f76086cb491949bc2e7619dbad /net/sunrpc
parent99dc2ef0397d082b63404c01cf841cf80f1418dc (diff)
SUNRPC: Fix a slow server-side memory leak with RPC-over-TCP
Jan Schunk reports that his small NFS servers suffer from memory exhaustion after just a few days. A bisect shows that commit e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_sendmsg() call") is the first bad commit. That commit assumed that sock_sendmsg() releases all the pages in the underlying bio_vec array, but the reality is that it doesn't. svc_xprt_release() releases the rqst's response pages, but the record marker page fragment isn't one of those, so it is never released. This is a narrow fix that can be applied to stable kernels. A more extensive fix is in the works. Reported-by: Jan Schunk <scpcom@gmx.de> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218671 Fixes: e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_sendmsg() call") Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Jakub Kacinski <kuba@kernel.org> Cc: David Howells <dhowells@redhat.com> Reviewed-by: David Howells <dhowells@redhat.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/svcsock.c10
1 files changed, 1 insertions, 9 deletions
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 545017a3daa4..6b3f01beb294 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1206,15 +1206,6 @@ err_noclose:
* MSG_SPLICE_PAGES is used exclusively to reduce the number of
* copy operations in this path. Therefore the caller must ensure
* that the pages backing @xdr are unchanging.
- *
- * Note that the send is non-blocking. The caller has incremented
- * the reference count on each page backing the RPC message, and
- * the network layer will "put" these pages when transmission is
- * complete.
- *
- * This is safe for our RPC services because the memory backing
- * the head and tail components is never kmalloc'd. These always
- * come from pages in the svc_rqst::rq_pages array.
*/
static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp,
rpc_fraghdr marker, unsigned int *sentp)
@@ -1244,6 +1235,7 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp,
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec,
1 + count, sizeof(marker) + rqstp->rq_res.len);
ret = sock_sendmsg(svsk->sk_sock, &msg);
+ page_frag_free(buf);
if (ret < 0)
return ret;
*sentp += ret;