From: Andreas Gruenbacher Date: Sat, 10 Dec 2022 01:21:32 +0000 (+0100) Subject: gfs2: Make glock lru list scanning safer X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=228804a35caa7edae4a81049281e7f106dea1ad1;p=linux.git gfs2: Make glock lru list scanning safer In __gfs2_glock_put(), remove the glock from the lru list *after* dropping the glock lock. This prevents deadlocks against gfs2_scan_glock_lru(). In gfs2_scan_glock_lru(), make sure that the glock's reference count is zero before moving the glock to the dispose list. This skips glocks that are marked dead as well as glocks that are still in use. Additionally, switch to spin_trylock() as we already do in gfs2_dispose_glock_lru(); this alone would also be enough to prevent deadlocks against __gfs2_glock_put(). Signed-off-by: Andreas Gruenbacher --- diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 05ef0ffa7ea6a..fbfbf7a2feac7 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -274,9 +274,8 @@ static void __gfs2_glock_put(struct gfs2_glock *gl) struct address_space *mapping = gfs2_glock2aspace(gl); lockref_mark_dead(&gl->gl_lockref); - - gfs2_glock_remove_from_lru(gl); spin_unlock(&gl->gl_lockref.lock); + gfs2_glock_remove_from_lru(gl); GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders)); if (mapping) { truncate_inode_pages_final(mapping); @@ -1995,9 +1994,14 @@ static long gfs2_scan_glock_lru(int nr) break; /* Test for being demotable */ if (!test_bit(GLF_LOCK, &gl->gl_flags)) { - list_move(&gl->gl_lru, &dispose); - atomic_dec(&lru_count); - freed++; + if (!spin_trylock(&gl->gl_lockref.lock)) + continue; + if (!gl->gl_lockref.count) { + list_move(&gl->gl_lru, &dispose); + atomic_dec(&lru_count); + freed++; + } + spin_unlock(&gl->gl_lockref.lock); } } if (!list_empty(&dispose))