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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.3 Subject: Re: [PATCH] mm/slub: remove dead code for debug caches on deactivate_slab() Content-Language: en-US To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20221014114322.97512-1-42.hyeyoo@gmail.com> <82e8147e-f031-6bc2-9395-56d2052e62cb@suse.cz> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666609860; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=c9LyPhw0fn06VJLpIWBBedHqVCQTOByd+fZNTw6i+9w=; b=76xnCzyjb66Zu70F85xU2keAAueQafXxwVdWltSrpNhc0aVoK8496zfYAqg32YWQpFCXN3 b60RMcQ7OIsgQtWr4IxBk9nmo2sKGp43X2kFADYIdxkBYZMaqweETnTqr0PFXfXVI4AT3K rTccuRVuOQ4tApAQ/8+/1VBAKUF29h4= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="P7qhGZV/"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=DbpVXtLX; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666609860; a=rsa-sha256; cv=none; b=QCkHTQBLAyeWAOdTR0zcG/uOxbvNr+dBuin81kTRP2rqCg7YoodvmtMkhqStM2GlqOknOA 0U+yT5kHVLCpsPkoS6NOCoseKFntoSuCXJ6m5o9IQeBGV7SKH7aHSeAL11RAWNacUrsABW jF6hKTFdIXBj4R90LNGHzSYkSMcHDSc= X-Stat-Signature: qkhh1pxjaj38cmns1sxds88d9msa8i3c X-Rspam-User: Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="P7qhGZV/"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=DbpVXtLX; spf=pass (imf17.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8F9214003A X-HE-Tag: 1666609860-969701 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 10/22/22 06:14, Hyeonggon Yoo wrote: > On Fri, Oct 21, 2022 at 12:43:42PM +0200, Vlastimil Babka wrote: >> On 10/14/22 13:43, Hyeonggon Yoo wrote: >> > After commit c7323a5ad0786 ("mm/slub: restrict sysfs validation to debug >> > caches and make it safe"), SLUB does not take a slab from partial list for >> >> I'm confused by "SLUB does not take a slab from partial list" here. Did you >> mean something like "SLUB never installs (even temporarily) a percpu slab >> for debug caches"? > > Yes. > >> So that means we never deactivate percpu slabs for debug >> caches. > > Yes. > >> And since debug caches are also the only ones that use the full >> list, we no longer need to care about the full list in deactivate_slab(), right? > > Yes, You got it right, exactly! > > Let me rephrase: > > "After commit c7323a5ad0786 ("mm/slub: restrict sysfs validation to debug > caches and make it safe"), SLUB never installs percpu slab for debug caches > and thus never deactivates percpu slab for them. > > Since only some of debug caches care about the full list, SLUB no longer > deactivates to full list. Remove dead code in deactivate_slab()." > > > Feel free to change this ;-) Great, thanks! Pushed to slab/for-6.2/cleanups