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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8B55C369A2 for ; Fri, 11 Apr 2025 18:13:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E9FEC680020; Fri, 11 Apr 2025 14:12:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E4F4968001E; Fri, 11 Apr 2025 14:12:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D3D7D680020; Fri, 11 Apr 2025 14:12:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id B2D9168001E for ; Fri, 11 Apr 2025 14:12:59 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 2ADC61206DB for ; Fri, 11 Apr 2025 18:13:00 +0000 (UTC) X-FDA: 83322559320.08.535506F Received: from mail-qk1-f176.google.com (mail-qk1-f176.google.com [209.85.222.176]) by imf24.hostedemail.com (Postfix) with ESMTP id 4AF25180006 for ; Fri, 11 Apr 2025 18:12:58 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=nsYNW6DS; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf24.hostedemail.com: domain of shakeel.butt@gmail.com designates 209.85.222.176 as permitted sender) smtp.mailfrom=shakeel.butt@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744395178; 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=RohNaCbynXMsTU9AdMmyEMzpA/tTHrz5QG5mLFjKvQE=; b=VkJYL0hVZAho4gAUIctl40c917/EuRuoEcnToyNuFO9KiDt5yub+LhhSXMZMPFrVOudnKS 1Y7msm1KMZzCehu44kp0NsRWe9TSNRkOa4vdPNxgc2J2jQUnUlb8R1gYvoEIVU1xOH9gP0 cl1sJeR+DmHVwoVJBnC2Qz5roT1EKCE= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=nsYNW6DS; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf24.hostedemail.com: domain of shakeel.butt@gmail.com designates 209.85.222.176 as permitted sender) smtp.mailfrom=shakeel.butt@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744395178; a=rsa-sha256; cv=none; b=4o1p0yiJ61Pgyu6kf5emJP4SP7lIVhVWF+zG4XiD0mkF2DQDeE77gRM26JH7HcSK/04xVn N8C+CFXjj8ZSPhVS0pzKKjc/Wdcm/ZLA0T/JuNgqA1mkTHbyWpP4OVToQy1RDJBKbzCCt/ KrRfGgfq8jXTS0o/djE+0WT8byHKJNc= Received: by mail-qk1-f176.google.com with SMTP id af79cd13be357-7c5a88b34a6so227588585a.3 for ; Fri, 11 Apr 2025 11:12:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1744395177; x=1744999977; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=RohNaCbynXMsTU9AdMmyEMzpA/tTHrz5QG5mLFjKvQE=; b=nsYNW6DST2zJMsXmYg+Bdo90OU4V3ObPAq/ifUvtvJPhHBV/vpxPFLSeJ/e8lE14hu GCAnhZeHAIalUNtDEbnO7YO+x8woAdGHR/eFeNjc05zWPI7hdNuaLT7+ntxv9QMn7xM4 ua9vCNpSI9pyMmDFci59ZQZlWqH8G+UVc8VhRWTiMD5EfYLGxWsH7xrYljBQjgr6Bvm9 68l4PUpVZKvATAUsO46VcB1z+pA6fuYtFVRH1BYv8/rVFTvO6iYqhQ+acrZthWKdEuf1 oOIsyQ9I1GTGChBKW3tl/mfk2y8jHxIPiFm5fWcfGjsnihpC6uKjItFnhgnA+Rn+NdH8 swKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744395177; x=1744999977; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=RohNaCbynXMsTU9AdMmyEMzpA/tTHrz5QG5mLFjKvQE=; b=F2/e8ZKVYdACAkFdTldHxU/pW4iJAuj+PyB/Ic9/g1KmpkkIFJxWPFx7/PO9lMR1sp J2sJh5hm4xzbKPwXIlin3G9rgG+7/Qng+GER6gpUI5xK5QIEISF2wr66sBXTiNW7pGuv 3NLg/gu4N+bHbu55RBWnGvu6jMiYh4wZ/KCnxxZQc+PCSqE5F2VLXjHalGfP3YxpRuJn JSmW6tC7MMT1D7ByYcZ2H0d4B0VR3g2mEF6Rbg831wiK+/HflX9Y3Bl3rDW40tGESkxo Ex2YLOmAIVdImPZCB4EOdIhmrK/f0WtiCxdTGNKFXzCHKq4LnwQPD6QBpJfMsI+hp50D psKQ== X-Forwarded-Encrypted: i=1; AJvYcCWsXrtCZarBo15EpyUfav+MzOr5OWq3y1pTq4Pg0yU2hEsIQhUh4uKu6Hu3Kor6vcSz//sG4Ynp7w==@kvack.org X-Gm-Message-State: AOJu0YzoHo6N2Ya2BEc4r1D9/Gj9Ml+bwjrTKeUpzu463sktEQVpa/Lf YcVMQXL+N1GEKMo9Nm6oVSVJ/DFWMKBgsKKhQDptCT+khZ40KvkESgaW4SbB9lNsfOgDp2kXyTe oB/qgYNpLpEIq+mJxqnmHnYB/r0Q= X-Gm-Gg: ASbGncsVG6VrLRR6ZDRnJyj1YndnXa8jfFxUp90B3UaawfL023iRDUCCyoRzVtVN8Uw CiXh9aVxesYFN/9AitXKsfb12Owwu7eHMsTBnFV1Hbd+1DwWH1Algxw1D2NdRDpoQjLiqUmlIf+ l4hwMMDkliQL3vj8eqoIv18Fak1cnpGDXMcxNKMWhcl7/EbNAPaV2HeWDBo7O13hw3D5g= X-Google-Smtp-Source: AGHT+IG8jVgxtwWubehVN+Idyf1Ufevy60rGqvVQAG1oqRSMZHvG5QfgPIhp6kOOvLpu3Hu/Kwxt+gKP7lJmYuDJNw4= X-Received: by 2002:a05:620a:4399:b0:7c5:6396:f161 with SMTP id af79cd13be357-7c7af20ba80mr660931985a.49.1744395177325; Fri, 11 Apr 2025 11:12:57 -0700 (PDT) MIME-Version: 1.0 References: <20250410210623.1016767-1-shakeel.butt@linux.dev> <0e9e2d5d-ec64-4ad4-a184-0c53832ff565@suse.cz> <8cce9a28-3b02-4126-a150-532e92c0e7f8@suse.cz> In-Reply-To: <8cce9a28-3b02-4126-a150-532e92c0e7f8@suse.cz> From: Shakeel Butt Date: Fri, 11 Apr 2025 14:12:46 -0400 X-Gm-Features: ATxdqUEuqDVleemKEFKk_6Ulu3ecA-4XDITgG6BPtj9oe0wu99PMHvXpTs2Zmaw Message-ID: Subject: Re: [PATCH] memcg: decouple memcg_hotplug_cpu_dead from stock_lock To: Vlastimil Babka Cc: Sebastian Andrzej Siewior , Shakeel Butt , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Yosry Ahmed , Waiman Long , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 4AF25180006 X-Stat-Signature: 87nbxicmbucocj45f49ama7itd533di6 X-Rspam-User: X-HE-Tag: 1744395178-938935 X-HE-Meta: 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 kmA0WmSg TPx8w4RZ6+tipBSZlYDa+fp+N/HeYcVqbvwahOWgw+qkBsUaqIySioON3c7nkEjrQjF7bcO8cGMI9XIw6IelEHYvuE1hRiazD7k3CpnbFKBETgfDBDou7NvAvWigTJ2igGe1/WQ4gjtJQbXgTjfPFsKUYrMu41Bgw2Xdtc+ADDP30BvdE75FEFhBtHGGaE7MpEV3vYDCPELdfpFAOn/E38jrwMmLJ9szFRIW2Vl3vsSDSVjGKBotFV/nQR6vFIFUJtJ5vbrSbKij2FBAQqN1yJCoS5nfVVLXzCneuOpn6dmJd8hblTdQI6aBB0t8pgXZvOuIDyFHCrDh9+nVZNEGShRv8whYca8lEpNl7oXRP9obc5Y0M75hHafRh5bVJ9d4FOLMxodCoq7wNSz7c+qnDokfpcw== 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: List-Subscribe: List-Unsubscribe: On Fri, Apr 11, 2025 at 2:06=E2=80=AFPM Vlastimil Babka wr= ote: > > On 4/11/25 19:54, Shakeel Butt wrote: > > (my migadu/linux.dev stopped working and I have to send through gmail, > > sorry for any formatting issue) > > > > I don't see how local_irq_save() will break anything. We are working on > > a stock of a dead remote cpu. We actually don't even need to disable ir= q > > or need local cpu's local_lock. It is actually the calls to > > __mod_memcg_lruvec_state() and __mod_memcg_state() in > > __drain_obj_stock() which need irq-disabled on non-RT kernels and for > > RT-kernels they already have preempt_disable_nested(). > > > > Disabling irq even on RT seems excessive but this is not a performance > > critical code, so I don't see an issue unless there is > > local_lock_irqsave() alternative which does not disables irqs on RT > > kernels. > > local_lock_irqsave() does not disable irqs on RT kernels :) Sorry, I wanted to say local_irq_save() here instead of local_lock_irqsave(= ). > so keeping > local_lock as is would do the irq disable on !RT and be more RT-friendly = on > RT. It's just wrong from the logical scope of the lock to perform it on a > different cpu than the stock we modify. If one day we have some runtime > checks for that, they would complain. Basically I don't want to use stock_lock here. Maybe I should explore adding a new local_lock for __mod_memcg_lruvec_state and __mod_memcg_state.