Date: Wed, 27 Apr 2016 10:39:29 -0500 (CDT) From: Christoph Lameter <cl@...ux.com> To: Andrew Morton <akpm@...ux-foundation.org> cc: Thomas Garnier <thgarnie@...gle.com>, Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>, Kees Cook <keescook@...omium.org>, gthelen@...gle.com, labbott@...oraproject.org, kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [PATCH v4] mm: SLAB freelist randomization On Tue, 26 Apr 2016, Andrew Morton wrote: > : CONFIG_FREELIST_RANDOM bugs me a bit - "freelist" is so vague. > : CONFIG_SLAB_FREELIST_RANDOM would be better. I mean, what Kconfig > : identifier could be used for implementing randomisation in > : slub/slob/etc once CONFIG_FREELIST_RANDOM is used up? > > but this pearl appeared to pass unnoticed. Ok. lets add SLAB here and then use this option for the other allocators as well. > > + /* If it fails, we will just use the global lists */ > > + cachep->random_seq = kcalloc(count, sizeof(freelist_idx_t), GFP_KERNEL); > > + if (!cachep->random_seq) > > + return -ENOMEM; > > OK, no BUG. If this happens, kmem_cache_init_late() will go BUG > instead ;) > > Questions for slab maintainers: > > What's going on with the gfp_flags in there? kmem_cache_init_late() > passes GFP_NOWAIT into enable_cpucache(). > > a) why the heck does it do that? It's __init code! enable_cpucache() was called when a slab cache was reconfigured by writing to /proc/slabinfo. That was changed awhile back when the memcg changes were made ot slab. So now its ok to be made init code. > Finally, all callers of enable_cpucache() (and hence of > cache_random_seq_create()) are __init, so we're unnecessarily bloating > up vmlinux. Could someone please take a look at this as a separate > thing? Hmmm. Well if that is the case then lots of stuff could be straightened out. Joonsoo?
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