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authorBenjamin Marzinski <bmarzins@redhat.com>2009-06-30 13:51:11 -0500
committerSteven Whitehouse <swhiteho@redhat.com>2009-07-30 10:59:28 +0100
commita51b56fff3f04fc5aa66b21a2a6d693ee9862d66 (patch)
treee93c25ebe818e7a157f2b878a9512ada0f2f2bd1 /fs/gfs2/glock.c
parent1946f70ab5e4eb8b54a8eaaedba2293a3750ab7e (diff)
downloadconfigs-a51b56fff3f04fc5aa66b21a2a6d693ee9862d66.tar.gz
GFS2: Fix panic in glock memory shrinker
It is possible for gfs2_shrink_glock_memory() to check a glock for demotion that's in the process of being freed by gfs2_glock_put(). In this case, gfs2_shrink_glock_memory() will acquire a new reference to this glock, and then try to free the glock itself when it drops the refernce. To solve this, gfs2_shrink_glock_memory() just needs to check if the glock is in the process of being freed, and if so skip it without ever unlocking the lru_lock. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Acked-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2/glock.c')
-rw-r--r--fs/gfs2/glock.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index fdb796c4f94..827136ee794 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1314,6 +1314,10 @@ static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask)
list_del_init(&gl->gl_lru);
atomic_dec(&lru_count);
+ /* Check if glock is about to be freed */
+ if (atomic_read(&gl->gl_ref) == 0)
+ continue;
+
/* Test for being demotable */
if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
gfs2_glock_hold(gl);