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=-0.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 C5FFBC4361B for ; Sun, 20 Dec 2020 01:56:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4C3FC23A00 for ; Sun, 20 Dec 2020 01:56:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C3FC23A00 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmx.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 93EA16B005C; 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Sun, 20 Dec 2020 01:56:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1608429380; bh=vXUawh3kPUtcXgR/FybC5uzJbN+zai3TrH7SO3d14Is=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=FfTBJHB83Yn9N/NPeJ6Mm7Cpa80BgLt/qZjztz4UZd06McV1++e4xqp0y8Mr1iw+C NDRnvFjYJjJV5bWllZgHNMZ0y1IInbjVmsCeOyJwOZoFMAxV7F/UP0IeNRFeSLpVdy +hJCwipa1TIZY2sh8ayvBFdO1Aml5CxlXN2aonbM= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.221.150.14]) by mail.gmx.com (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MFKGZ-1ktFkL0NFx-00FgeW; Sun, 20 Dec 2020 02:56:20 +0100 Message-ID: <53dd6a82bbb2a9a102b420899281633a3e1b37a8.camel@gmx.de> Subject: Re: [PATCH] zsmalloc: do not use bit_spin_lock From: Mike Galbraith To: Vitaly Wool , LKML , linux-mm Cc: Barry Song , Sebastian Andrzej Siewior , Minchan Kim , NitinGupta Date: Sun, 20 Dec 2020 02:56:18 +0100 In-Reply-To: <20201220002228.38697-1-vitaly.wool@konsulko.com> References: <18669bd607ae9efbf4e00e36532c7aa167d0fa12.camel@gmx.de> <20201220002228.38697-1-vitaly.wool@konsulko.com> Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:VGiNPUjzT+E+GM6QKupqdR66ABAQZq/3HoCKx4v30GHTPaPvsFP +5vRKde64mKEUlumbSbzH5aYBuuTHgqGC6VPqZUpQ+av4KNyoCh/w5xt4XJGuLeocrNpN71 1XttEmGwlpKHWTXpjYpCkjbCP46dcKYveW/WMaBKhRFf1z1m4IF0U8y0HuGmrDsPmlw6OoG 7GbDYrs1pFw3QpYEP+K2g== X-UI-Out-Filterresults: notjunk:1;V03:K0:HyBZqduQu1Y=:ONBy/YVfBUPMs+eb+D58Cx RBBiazb/NqBC4wgVA8oj+MI07e4a7YvQA1E9fpxHGdXYgaMmQjeLg6iaO3/0B4pIN8rfKXs2y rEs4FeHkMX1HSNYW5Ilz4i27X9lTNnwPPWjy/pK8sx7eRTBHzloz6b3HTbY6mV7596F4xWqG3 aDAGOfdjBzt3fvhSwIi9whddOCgVTfSZm0uz4I5bXc7iGPjLWKW/+N4SNzl9oRbx6/rKzfl3y 5V2jcGTGlmnYzNCLg+ZViTorMVCfKQXEPzjX3L4Bo622k0VJ/PpfisvoEVy179dJNhPWZn/wz 8/CGdpkcHpCvKrwm8Xsumbvkta3vPBSg+ul2emxuZfkOWYsFrOJz/FgQl/UrkaE+uEj5ddqRR yl8XlvGj4y3BtUF9UbOyDZr7CMaiJY8fyTpzZdDJ2k2OSKFybn2PVUuR33YZQyzh/Gvm441V0 VDDb71AWVyginlL4GVU7Q5X2SpZcz+LAWGADrSV/747/TUw/AmXcgmCjYLbYyKbpgr9jvqiLh eXcMdcxnveUGfxPTEKmIQsNHbNSQ5NtjTHuxOpyUuJ97mq1Cl2LcHTxiOi2evQDymZhe3RaTe Org470QE1cBEvY5uoUvchbNMCTNa0TsB5wh3vioA9Uk3eeNbt01o0FKjpYqaG8XlylEPcPsZM VXC/0Me/BC+rKzyt8xeqc/MAFjjh52QfsSaeBblP7CZYAFgLLiYuSGexu3hgdSLyd/qOo53nL tlzlzu4Uxxl8HT8Jla2HDLpJcBlhBnrMdwm1/HQqx+a+0pXBhcQJ/Udc5rOkGqdJX1uN2axDY CZezCObgCJXu3Adh8hdiz3b7L+ZrMXG9BjIcKC2j5vFPvEKtA0aYHzR1zJ4LCD1uT4NCuefe+ nOxCYvyGKlno4xxdbi0Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000074, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, 2020-12-20 at 02:22 +0200, Vitaly Wool wrote: > zsmalloc takes bit spinlock in its _map() callback and releases it > only in unmap() which is unsafe and leads to zswap complaining > about scheduling in atomic context. > > To fix that and to improve RT properties of zsmalloc, remove that > bit spinlock completely and use a bit flag instead. > -static void pin_tag(unsigned long handle) __acquires(bitlock) > +static void pin_tag(unsigned long handle) > { > - bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle); > + preempt_disable(); > + while(test_and_set_bit(HANDLE_PIN_BIT, (unsigned long *)handle)) > + cpu_relax(); > + preempt_enable(); > } If try doesn't need to disable preemption, neither does pin. -Mike