OOM kills when running fsstress on CIFS

[Jeff Layton <jlayton@redhat.com>]

Since 2.6.34, I've been able to consistently reproduce OOM kills when running fsstress (from the LTP suite) on CIFS. I spent some time yesterday and bisected it down to this patch:

---------------------[snip]---------------------
commit 315e995c63a15cb4d4efdbfd70fe2db191917f7a
Author: Nick Piggin <npiggin@suse.de>
Date:   Wed Apr 21 03:18:28 2010 +0000

    [CIFS] use add_to_page_cache_lru
    
    add_to_page_cache_lru is exported, so it should be used. Benefits over
    using a private pagevec: neater code, 128 bytes fewer stack used, percpu
    lru ordering is preserved, and finally don't need to flush pagevec
    before returning so batching may be shared with other LRU insertions.
    
    Signed-off-by: Nick Piggin <npiggin@suse.de>
    Reviewed-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
    Signed-off-by: Steve French <sfrench@us.ibm.com>
---------------------[snip]---------------------

Here's how I've been reproducing it:

Mount up a samba share with -o sec=krb5i,nounix,noserverino

Run: fsstress -d /path/to/dir/on/cifs/ -n 1000 -l0 -p8

...within an hour or two, I start getting OOM kills. After backing out
the patch above, I was able to run the test overnight. I'm not sure yet
what the actual problem is, but there seems to be something wrong with
that patch.

Thoughts?
-- 
Jeff Layton <jlayton@redhat.com>