From: Badari Pulavarty <pbadari@us.ibm.com>
Date: Fri, 22 Dec 2006 09:06:23 +0000 (-0800)
Subject: [PATCH] Fix for shmem_truncate_range() BUG_ON()
X-Git-Tag: v2.6.20-rc2~53
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92a3d03aab912624cae799e5772a6eb2ef55083f;p=linux-2.6

[PATCH] Fix for shmem_truncate_range() BUG_ON()

Ran into BUG() while doing madvise(REMOVE) testing.  If we are punching a
hole into shared memory segment using madvise(REMOVE) and the entire hole
is below the indirect blocks, we hit following assert.

	        BUG_ON(limit <= SHMEM_NR_DIRECT);

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/mm/shmem.c b/mm/shmem.c
index 4bb28d218e..70da7a0981 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -515,7 +515,12 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
 			size = SHMEM_NR_DIRECT;
 		nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
 	}
-	if (!topdir)
+
+	/*
+	 * If there are no indirect blocks or we are punching a hole
+	 * below indirect blocks, nothing to be done.
+	 */
+	if (!topdir || (punch_hole && (limit <= SHMEM_NR_DIRECT)))
 		goto done2;
 
 	BUG_ON(limit <= SHMEM_NR_DIRECT);