On Tue, 9 Jun 2015 21:00:58 -0500 (CDT) Christoph Lameter <cl@xxxxxxxxx> wrote: > On Tue, 9 Jun 2015, Andrew Morton wrote: > > > > Why do this at all? > > > > For the third time: because there are approx 200 callsites which are > > already doing it. > > Did some grepping and I did see some call sites that do this but the > majority has to do other processing as well. > > 200 call sites? Do we have that many uses of caches? Typical prod system > have ~190 caches active and the merging brings that down to half of that. I didn't try terribly hard. z:/usr/src/linux-4.1-rc7> grep -r -C1 kmem_cache_destroy . | grep "if [(]" | wc -l 158 It's a lot, anyway. > > More than half of the kmem_cache_destroy() callsites are declining that > > value by open-coding the NULL test. That's reality and we should recognize > > it. > > Well that may just indicate that we need to have a look at those > callsites and the reason there to use a special cache at all. This makes no sense. Go look at the code. drivers/staging/lustre/lustre/llite/super25.c, for example. It's all in the basic unwind/recover/exit code. > If the cache > is just something that kmalloc can provide then why create a special > cache. On the other hand if something special needs to be accomplished > then it would make sense to have special processing on kmem_cache_destroy. This has nothing to do with anything. We're talking about a basic "if I created this cache then destroy it" operation. It's a common pattern. mm/ exists to serve client code and as a lot of client code is doing this, we should move it into mm/ so as to serve client code better. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>