On Mon, Nov 23, 2020 at 12:10 AM Alexander Aring <[email protected]> wrote: > 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 <[email protected]> > --- > 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 >
Thanks. I've added this to for-next for now, but I'll try to push this to Linus before the 5.10 release. Andreas
