Commit cf0a586c authored Apr 01, 2009 by Greg Banks Committed by J. Bruce Fields May 27, 2009

knfsd: fix reply cache memory corruption



Fix a regression in the reply cache introduced when the code was
converted to use proper Linux lists.  When a new entry needs to be
inserted, the case where all the entries are currently being used
by threads is not correctly detected.  This can result in memory
corruption and a crash.  In the current code this is an extremely
unlikely corner case; it would require the machine to have 1024
nfsd threads and all of them to be busy at the same time.  However,
upcoming reply cache changes make this more likely; a crash due to
this problem was actually observed in field.

Signed-off-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

parent fca4217c

fs/nfsd/nfscache.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -174,8 +174,8 @@ nfsd_cache_lookup(struct svc_rqst *rqstp, int type)
		}
		}

		/* This should not happen */
		if (rp == NULL) {
		/* All entries on the LRU are in-progress. This should not happen */
		if (&rp->c_lru == &lru_head) {
		static int complaints;

		printk(KERN_WARNING "nfsd: all repcache entries locked!\n");