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Sun, 09 Oct 2022 20:54:37 -0700 (PDT) Date: Sun, 9 Oct 2022 20:54:36 -0700 (PDT) From: David Rientjes To: Rasmus Villemoes cc: Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: slub: remove dead and buggy code from sysfs_slab_add() In-Reply-To: <20220930084742.771804-1-linux@rasmusvillemoes.dk> Message-ID: <48a02db7-f59e-b80b-b879-3fd679623945@google.com> References: <20220930084742.771804-1-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665374079; a=rsa-sha256; cv=none; b=OvqbQuOxnrEqKga7NqBrjDPSnd28sC18fmhBy4Qnx28SKaPigJgioh5ZBt3XLsdWndRiCj sngjGTXjzR5UCezkTiOLjarxCrIzKFNe5U7jrEnyKPkRA+R/D2WWVa1mccDFrkMNwzLD6o IhAp8jThx3mBOEvaiBjM3IFaFQG+/nM= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=grP00eNB; 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spf=pass (imf14.hostedemail.com: domain of rientjes@google.com designates 209.85.216.49 as permitted sender) smtp.mailfrom=rientjes@google.com X-HE-Tag: 1665374078-648022 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 30 Sep 2022, Rasmus Villemoes wrote: > The function sysfs_slab_add() has two callers: > > One is slab_sysfs_init(), which first initializes slab_kset, and only > when that succeeds sets slab_state to FULL, and then proceeds to call > sysfs_slab_add() for all previously created slabs. > > The other is __kmem_cache_create(), but only after a > > if (slab_state <= UP) > return 0; > > check. > > So in other words, sysfs_slab_add() is never called without > slab_kset (aka the return value of cache_kset()) being non-NULL. > > And this is just as well, because if we ever did take this path and > called kobject_init(&s->kobj), and then later when called again from > slab_sysfs_init() would end up calling kobject_init_and_add(), we > would hit > > if (kobj->state_initialized) { > /* do not error out as sometimes we can recover */ > pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.\n", > dump_stack(); > } > > in kobject.c. > > Signed-off-by: Rasmus Villemoes Acked-by: David Rientjes