On Mon, May 20, 2013 at 11:14:27AM +0200, Oskar Andero wrote: > Add a BUG_ON to catch any illegal value from the shrinkers. This fixes a > potential bug if scan_objects returns a negative other than -1, which > would lead to undefined behaviour. > > Cc: Glauber Costa <[email protected]> > Cc: Dave Chinner <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Hugh Dickins <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Signed-off-by: Oskar Andero <[email protected]> > --- > mm/vmscan.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 6bac41e..fbe6742 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -293,6 +293,7 @@ shrink_slab_one(struct shrinker *shrinker, struct > shrink_control *shrinkctl, > ret = shrinker->scan_objects(shrinker, shrinkctl); > if (ret == -1) > break; > + BUG_ON(ret < -1); > freed += ret; > > count_vm_events(SLABS_SCANNED, nr_to_scan);
NACK. we've got to fix the damn shrinkers first. If you want this sort of guard added to the patchset Glauber and I are working on that does this, then discuss it in the context of that patch set. Even if you do, you'll get the same answer: we need to first all the busted shrinkers before we even consider being nasty about enforcing the API constraints to prevent furture breakage. If you want to do something useful, look at all the comments about broken shrinkers in Glauber's patch set and work with the owners of the code to understand what they really need and get them fixed. -Dave. -- Dave Chinner [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
