On Sat, Jan 06, 2018 at 10:06:54AM -0800, Eric Biggers wrote: > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > This reverts commit d5dabd633922ac5ee5bcc67748f7defb8b211469. > > This patch did absolutely nothing, because ->c_entry_count is unsigned. > > In addition if there is a bug in how mbcache maintains its entry count, > it needs to be fixed, not just hacked around. (There is no obvious bug, > though.) Right, if we're going to add a check, we should be checking to make sure cache->c_entry_count is not zero before we decrement it in mb_cache_entry_delete(). I will note that it's quite possible the error is in do_shrink_slab() --- it's already dodgy that it assigns an unsigned long from shrinker->count_objects to a signed long. Then it multiplies it by (4 * nr_scanned) / shrinker->seeks. So there are plenty of opportunities to get the "negative objects to delete" message that has nothing to do with value returned from mb_cache_count(). Regards, - Ted
