Messages in this thread | | | Date | Mon, 5 Apr 2021 18:23:49 +0000 | From | Al Viro <> | Subject | Re: [syzbot] WARNING in mntput_no_expire (2) |
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On Mon, Apr 05, 2021 at 07:08:01PM +0200, Christian Brauner wrote:
> Ah dentry count of -127 looks... odd.
dead + 1...
void lockref_mark_dead(struct lockref *lockref) { assert_spin_locked(&lockref->lock); lockref->count = -128; }
IOW, a leaked (uncounted) reference to dentry, that got dget() called on it after dentry had been freed.
IOW, current->fs->pwd.dentry happens to point to an already freed struct dentry here. Joy...
Could you slap
spin_lock(¤t->fs->lock); WARN_ON(d_count(current->fs->pwd.dentry) < 0); spin_unlock(¤t->fs->lock);
before and after calls of io_issue_sqe() and see if it triggers? We definitely are seeing buggered dentry refcounting here.
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