From a51b56fff3f04fc5aa66b21a2a6d693ee9862d66 Mon Sep 17 00:00:00 2001 From: Benjamin Marzinski Date: Tue, 30 Jun 2009 13:51:11 -0500 Subject: 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 Acked-by: Bob Peterson Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/gfs2') 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); -- cgit v1.2.3