Messages in this thread | | | Date | Mon, 20 May 2013 15:24:53 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH] mm: vmscan: add BUG_ON on illegal return values from scan_objects |
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On Mon, 20 May 2013, 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 <glommer@openvz.org> > Cc: Dave Chinner <dchinner@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Oskar Andero <oskar.andero@sonymobile.com> > --- > 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, this doesn't fix anything. I can see the intention, and for that it might make sense to turn this into VM_BUG_ON() so that anybody debugging an issue related to this with CONFIG_DEBUG_VM would get the indication, but I don't think we need to enforce the API with BUG_ON().
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