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knfsd: fix reply cache memory corruption

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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>
This commit is contained in:
Greg Banks 2009-04-01 07:28:15 +11:00 committed by J. Bruce Fields
parent fca4217c5b
commit cf0a586cf4
1 changed files with 2 additions and 2 deletions
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4
fs/nfsd/nfscache.c
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@ -174,8 +174,8 @@ nfsd_cache_lookup(struct svc_rqst *rqstp, int type)
} }
} }
/* This should not happen */ /* All entries on the LRU are in-progress. This should not happen */
if (rp == NULL) { if (&rp->c_lru == &lru_head) {
static int complaints; static int complaints;
printk(KERN_WARNING "nfsd: all repcache entries locked!\n"); printk(KERN_WARNING "nfsd: all repcache entries locked!\n");