From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19E1CC2B9F8 for ; Tue, 25 May 2021 16:00:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BCC73613F5 for ; Tue, 25 May 2021 16:00:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BCC73613F5 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 387696B0036; Tue, 25 May 2021 12:00:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 338576B006E; Tue, 25 May 2021 12:00:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 18AF26B0070; Tue, 25 May 2021 12:00:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0058.hostedemail.com [216.40.44.58]) by kanga.kvack.org (Postfix) with ESMTP id D9CB46B0036 for ; Tue, 25 May 2021 12:00:51 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 7312FA8E8 for ; Tue, 25 May 2021 16:00:51 +0000 (UTC) X-FDA: 78180216702.02.53568D0 Received: from mail-lj1-f169.google.com (mail-lj1-f169.google.com [209.85.208.169]) by imf11.hostedemail.com (Postfix) with ESMTP id 4FDEA200107D for ; Tue, 25 May 2021 16:00:43 +0000 (UTC) Received: by mail-lj1-f169.google.com with SMTP id a4so24006486ljd.5 for ; Tue, 25 May 2021 09:00:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=AlGDwi+fKb5zDo0UgCxQb6+0ejL9MD7uZrEbLSa4Oto=; b=F8IoZ31vbu3JuKyp9XnxNMl6YxtNA2oECxMIbLi9v7US/TCuDrFIPmY876ESiknlBc cAKK1IAGOHcTMDm51QNr9q62Lx/yjQC4eiavpb6wfgGZnDi8R1R24k+pZ5+7OWIBjSnt f9C0aKQJlR8IR67wEbnAeeJWeez+R+6+5yuntCPH5gVMbHonthRDAgW1/EI5npLjF1vh hZx92RzdJKVaAhRzMmxq2psslRuA4eZJGhEzyNUOh/fFOHmlGJGhJ56xXtI4VCj4fZJv giLk1Ue6Dnsmns3bHjtEQwj0Oz8LWpgllGSbx2TmVO8qpVtEearWBhhmTpzH3st0oC99 Pf/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=AlGDwi+fKb5zDo0UgCxQb6+0ejL9MD7uZrEbLSa4Oto=; b=dRuxFu3hDnlFZpLToF/Di4yzkfoFMTMpboTi+l9MKP2mM4ZJSjNTS5igdq6zLgSpDy Kce+eJQbWU83FVi9z386uB39+ZPZRZ+bFn4ygxC8BiyF/gHbEW33UEJLvYiEv1G7S8Qx ZNwgk2+jf2ipCHpurBou/+Jwdz/PqH+FDo8gymAJmIC1E6MtbXSAGiE8zrHN9MNNlPBq npinTj/OOBiQJ/r1qdshP2kgeC9adcHoP8CMY7fuJbwAlO0wR8sKnSqXDMtqWuaQqtBo t+bDuItT9tfThKQjyMnj5VN0H+G3CFWdjoWpl7K2A4+ytRbBL1y9n3Ga5uGTE/ANCbsb QNPg== X-Gm-Message-State: AOAM533fDefYfZXlj2rvgU4hBRbA28hWW7FkjcLBxnrJ/33RBh6CJlx4 9XUcRS0vEna4g0MFVs/kRyG/Mc4ySdP61lm25to3kA== X-Google-Smtp-Source: ABdhPJx9xYr2Q9z8EeDwQEaSd0fE2W8VGVS1cMT3ZD+4m9iso3u01S1B4hRaNGxuBydJN6h2WIrDsTxaLTS5pE2QPtU= X-Received: by 2002:a2e:b4ed:: with SMTP id s13mr21295934ljm.86.1621958449402; Tue, 25 May 2021 09:00:49 -0700 (PDT) MIME-Version: 1.0 References: <20210524233946.20352-1-vbabka@suse.cz> <20210524233946.20352-12-vbabka@suse.cz> In-Reply-To: <20210524233946.20352-12-vbabka@suse.cz> From: Jann Horn Date: Tue, 25 May 2021 18:00:23 +0200 Message-ID: Subject: Re: [RFC 11/26] mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc() To: Vlastimil Babka Cc: Linux-MM , kernel list , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=F8IoZ31v; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf11.hostedemail.com: domain of jannh@google.com designates 209.85.208.169 as permitted sender) smtp.mailfrom=jannh@google.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4FDEA200107D X-Stat-Signature: yf4pfpbmkfgproww8eintx19qpgd3ckz X-HE-Tag: 1621958443-860139 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 Tue, May 25, 2021 at 1:40 AM Vlastimil Babka wrote: > Continue reducing the irq disabled scope. Check for per-cpu partial slabs with > first with irqs enabled and then recheck with irqs disabled before grabbing > the slab page. Mostly preparatory for the following patches. [...] > diff --git a/mm/slub.c b/mm/slub.c [...] > if (slub_percpu_partial(c)) { > + local_irq_save(flags); > + if (unlikely(c->page)) { > + local_irq_restore(flags); > + goto reread_page; > + } > + if (unlikely(!slub_percpu_partial(c))) /* stolen by IRQ? */ > + goto new_objects; nit: I think this comment is wrong by the end of the patch series, since at that point, in RT configurations, it could also be stolen by another task, if I understand correctly what migrate_disable() means? Similarly the comment above ___slab_alloc() still talks about disabling preemption for bulk allocation.