On Wed, Aug 22, 2012 at 01:25:06PM -0700, Hugh Dickins wrote: > > > Probably more important would be to remove spin_lock() and spin_unlock() > > > (and INIT_LIST_HEAD) from simple_xattrs_free() - those are unnecessary > > > in shmem_evict_inode(), and wouldn't they be unnecessary whenever > > > simple_xattrs_free() gets called? > > > > Removing INIT_LIST_HEAD() it's possible by actually unlinking each xattr > > inside the loop before freeing them. still, it'll have to check if the list is > > empty or not, which might end up being the same? > > > > About the locking, I'm not sure, I'm investigating it. > > I think we have a misunderstanding. > > INIT_LIST_HEAD() is not expensive, I just meant to remove it because > I thought it unnecessary by that point. ah, I see. > Do you envisage anywhere that would call simple_xattrs_free() except > a filesystem's evict_inode()? cgroup does it differently and it's called in d_iput() path (see cgroup_diput), because it needs to selectively remove files upon remount. > By that point, the inode is on its way out of the system: nothing > much (yes, I am being a bit vague there ;) can get to it any more, > there's no need to reinitialize the list head and there's no need for > locking, because nothing else can be playing with those xattrs now. I agree with you. That's why I'm looking into it because I'm pretty sure I removed it at some point in the past and decided to put it back after investigating the easily reproducible oops. Sadly I managed to forget the analisys I did at the time. -- Aristeu -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
