From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Aring Date: Sun, 22 Nov 2020 18:10:24 -0500 Subject: [Cluster-devel] [PATCH gfs2/for-next] gfs2: Fix deadlock dumping resource group glocks Message-ID: <20201122231024.249253-1-aahringo@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Commit 0e539ca1bbbe ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump") introduced additional locking in gfs2_rgrp_go_dump, which is also used for dumping resource group glocks via debugfs. However, on that code path, the glock spin lock is already taken in dump_glock, and taking it again in gfs2_glock2rgrp leads to deadlock. This can be reproduced with: $ mkfs.gfs2 -O -p lock_nolock /dev/FOO $ mount /dev/FOO /mnt/foo $ touch /mnt/foo/bar $ cat /sys/kernel/debug/gfs2/FOO/glocks Fix that by not taking the glock spin lock inside the go_dump callback. Fixes: 0e539ca1bbbe ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump") Signed-off-by: Alexander Aring --- fs/gfs2/glops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c index 67f2921ae8d4..6cedeefb7b3f 100644 --- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -245,7 +245,7 @@ static void rgrp_go_inval(struct gfs2_glock *gl, int flags) static void gfs2_rgrp_go_dump(struct seq_file *seq, struct gfs2_glock *gl, const char *fs_id_buf) { - struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl); + struct gfs2_rgrpd *rgd = gl->gl_object; if (rgd) gfs2_rgrp_dump(seq, rgd, fs_id_buf); -- 2.26.2