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dkim=pass header.d=google.com header.s=20210112 header.b=nwlr6Rfx; spf=pass (imf30.hostedemail.com: domain of yosryahmed@google.com designates 209.85.221.46 as permitted sender) smtp.mailfrom=yosryahmed@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Stat-Signature: ei9qbdpedcu7ozf17rakdirjmp7czwjt X-Rspamd-Queue-Id: DF59780004 X-Rspamd-Server: rspam06 X-HE-Tag: 1660580205-727306 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 Mon, Aug 15, 2022 at 8:42 AM Yosry Ahmed wrote: > > On Mon, Aug 15, 2022 at 8:31 AM Johannes Weiner wrote: > > > > On Mon, Aug 15, 2022 at 06:46:46AM -0700, Yosry Ahmed wrote: > > > Yeah I understand this much, what I don't understand is why we charge > > > the zswap memory through objcg (thus tying it to memcg kmem charging) > > > rather than directly through memcg. > > > > The charged quantities are smaller than a page, so we have to use the > > byte interface. > > > > The byte interface (objcg) was written for slab originally, hence the > > link to the kmem option. But note that CONFIG_MEMCG_KMEM is no longer > > a user-visible option, and for all intents and purposes a fixed part > > of CONFIG_MEMCG. > > > > (There is the SLOB quirk. But I'm not sure anybody uses slob, let > > alone slob + memcg.) > > Thanks for the clarification, it makes sense to use the byte interface > here for this, and thanks for pointing out that CONFIC_MEMCG_KMEM is > not part of CONFIG_MEMCG. > > One more question :) memcg kmem charging can still be disabled even > with !CONFIG_MEMCG_KMEM, right? In this case zswap charging will also > be off, which seems like an unintended side effect, right? memcg kmem charging can still be disabled even with CONFIG_MEMCG_KMEM***