From: NeilBrown <neilb@suse.de>
To: Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: NFSv4.1 backchannel xprt problems.
Date: Wed, 09 Oct 2019 16:15:04 +1100 [thread overview]
Message-ID: <87tv8iqz3b.fsf@notabene.neil.brown.name> (raw)
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Hi,
I have a customer with a 4.12-based kernel who is experiencing memory
exhaustion.
There are over 100,000 rpc_rqst structures queue on sv_cb_list for
handing by the NFSv4 callback, which is idle.
The rpc_rqst.rq_xprt pointer points to freed memory.
I notice that that server code calls svc_xprt_get() on the xprt
before storing it in rq_xprt, but the client/backchannel code doesn't.
I'm wondering if the following might be useful.
I plan to explore the code a bit more tomorrow and if this still seems
likely I get the customer to test this change, but I thought I would
ask here as well incase someone more knowledgeable can give me any
pointers.
Thanks,
NeilBrown
diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c
index 339e8c077c2d..c95ca39688b6 100644
--- a/net/sunrpc/backchannel_rqst.c
+++ b/net/sunrpc/backchannel_rqst.c
@@ -61,6 +61,7 @@ static void xprt_free_allocation(struct rpc_rqst *req)
free_page((unsigned long)xbufp->head[0].iov_base);
xbufp = &req->rq_snd_buf;
free_page((unsigned long)xbufp->head[0].iov_base);
+ xprt_put(req->rq_xprt);
kfree(req);
}
@@ -85,7 +86,7 @@ struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
if (req == NULL)
return NULL;
- req->rq_xprt = xprt;
+ req->rq_xprt = xprt_get(xprt);
INIT_LIST_HEAD(&req->rq_bc_list);
/* Preallocate one XDR receive buffer */
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next reply other threads:[~2019-10-09 5:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 5:15 NeilBrown [this message]
2019-10-11 16:56 ` NFSv4.1 backchannel xprt problems J. Bruce Fields
2019-10-14 23:36 ` [PATCH] SUNRPC: backchannel RPC request must reference XPRT NeilBrown
2019-10-15 21:16 ` Trond Myklebust
2019-10-15 21:47 ` Chuck Lever
2019-10-15 23:23 ` NeilBrown
2019-10-16 3:04 ` Trond Myklebust
2019-10-16 4:38 ` NeilBrown
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