On Thu, Jan 18, 2024 at 12:50:37PM +0100, Andreas Gruenbacher wrote:
On Tue, Jan 16, 2024 at 9:53 PM Pavel Machek <pavel@xxxxxxx> wrote:Hi! > From: Andreas Gruenbacher <agruenba@xxxxxxxxxx> > > [ Upstream commit 4e58543e7da4859c4ba61d15493e3522b6ad71fd ] > > It turns out that the .freeze_super and .thaw_super operations require > the filesystem to manage the superblock refcount itself. We are using > the freeze_super() and thaw_super() helpers to mostly take care of that > for us, but this means that the superblock may no longer be around by > when thaw_super() returns, and gfs2_thaw_super() will then access freed > memory. Take an extra superblock reference in gfs2_thaw_super() to fix > that. Patch was broken during backport. > +++ b/fs/gfs2/super.c > @@ -1013,6 +1013,7 @@ static int gfs2_freeze(struct super_block *sb) > goto out; > } > > + atomic_inc(&sb->s_active); > for (;;) { > error = gfs2_lock_fs_check_clean(sdp, &sdp->sd_freeze_gh); > if (!error) > @@ -1034,6 +1035,7 @@ static int gfs2_freeze(struct super_block *sb) > error = 0; > out: > mutex_unlock(&sdp->sd_freeze_mutex); > + deactivate_super(sb); > return error; > } Notice the goto out? That now jumps around the atomic_inc, but we still do decrease. This will break 4.19, please fix or drop.Thanks, Pavel. Sasha, you don't want that fix without "gfs2: Rework freeze / thaw logic" and the follow-up fixes, and backporting that probably isn't going to be worth it.
I'll drop it, thanks! -- Thanks, Sasha
