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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 D3C1CC10F03 for ; Fri, 22 Mar 2019 14:35:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9091321916 for ; Fri, 22 Mar 2019 14:35:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9091321916 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 11C1D6B0007; Fri, 22 Mar 2019 10:35:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0CC576B0008; Fri, 22 Mar 2019 10:35:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED7306B000A; Fri, 22 Mar 2019 10:35:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by kanga.kvack.org (Postfix) with ESMTP id C96786B0007 for ; Fri, 22 Mar 2019 10:35:25 -0400 (EDT) Received: by mail-qk1-f200.google.com with SMTP id c67so2077131qkg.5 for ; Fri, 22 Mar 2019 07:35:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:subject:to:cc :references:from:openpgp:autocrypt:organization:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=pLPPXAfElSV+eLwLcnJGPUAEA79wHbNbWg4yR8J8abI=; b=dqzjnBMaXNmFzFN/prl8rxkQp6DPjQX/nDejs4azjIlrv9+OQGWj6+A+brREhKGQLU wtk261nT0++aqCPqcVJjkcx/4qlHfXYt0/DcyF7FmYhq34tvYNae4c2d3zLdwvjD3GBS ELiYD26jMV9iKDcb5B83PXipof3MC5yuuyXovwlN/e3iO2NVXx+sZFs5Xc9tB0ZO9yxl jG8mzE4UXK0K/X5XjTESYhRBE8z3fz2MmZbIVMN76R7bjCuVGziv3LJJVTytJlZtY9xc nzVyaCFMwKYSIw2jnFzWPNWcb56i+gHkFUU3yT+g5zve/N8lpjx+SFMesLvmglx3agpU RXVA== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=longman@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Gm-Message-State: APjAAAWDrPBkb7p/voiF1SlnNXR+IdBKB0JmHyVSKN2S47CJGVibYypX o984zkGjrxlKVmAg2eNYZh/1DLj52lrRfZiya86ZgE3vyB+kuV7I7JpIr7Dzgb5arl0dE+6s2Up xF0gYaXSClEKCfJ5zJ0+yragXdvA4Rmt3Oh75ugLZkoT+gHMxsVJtwYHmGxL3sa2wXw== X-Received: by 2002:ac8:2207:: with SMTP id o7mr8360585qto.376.1553265325463; Fri, 22 Mar 2019 07:35:25 -0700 (PDT) X-Google-Smtp-Source: APXvYqzoSQ+ImVtWlQtOoYQadgiBBrmS82DMp7HSy8eCR2+wyW3fUecHmExLPbg2iH7ObyyGjZnK X-Received: by 2002:ac8:2207:: with SMTP id o7mr8360504qto.376.1553265324551; Fri, 22 Mar 2019 07:35:24 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1553265324; cv=none; d=google.com; s=arc-20160816; b=S4E1AY8iUlxuanUdjMBByysDawi7oVvEbPMpR/gBZ/CU/xka9DRP0Ea8TYRScu0t3l ELKvkJWbA99qC77DLk1A+WnlrAJG2soB4Ao1wdcb+pykwvuQ6Dco/SmVnoSFlnSMeXo7 xUzOu2poYUq1g+tv5U8ghpAgRvZCjA/wt2tmOTPsOeE1IseX6ua5lcgQadz09X+11i/O 8DEWtGMbY7MITp8rx6N1PBgHaakwgALugoCfLIrdNAdIWoAZvrU9BRr7wh3EjfPUD8Gd qoLY8XVJ7H1gQefDF3q2R49j8CkOJAfJ2g9Ic9a1BwOK+HDFcI2NvReoiTZpd7NcL5Cf gpEg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-language:content-transfer-encoding:in-reply-to:mime-version :user-agent:date:message-id:organization:autocrypt:openpgp:from :references:cc:to:subject; bh=pLPPXAfElSV+eLwLcnJGPUAEA79wHbNbWg4yR8J8abI=; b=lbAWHGd6D+fegYih2Edf++a4ykXK7A7B4XWcXCNz2hzMSB294cPe7pKix10wuqCuBP J5M/nQYVTMBt7DyKEudfnhufTbZkXKNNUBBFhjAZatlyC+HLBfC3YRCld66AT4SeyQy9 Cd+qvESmIfKNjoxlfXccaD55xYg2Zh938Sga36u0DwaWKqq0SM0KmeKL3KpjQyfa9tEB /wK/ryfshvPIeC4Mc0ivh70yGUUoMQ5CONP1HDSJWxA7GJPv1tsCuVqds1u0NfQq0QB7 /eb0yGcRr3kjfVNPpZzqaHqwXjnGO+DhmWChCkF1gTKroMfSz1LKiRykIDZMjeW0mE0D hSTA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=longman@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id k7si4871032qvh.206.2019.03.22.07.35.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Mar 2019 07:35:24 -0700 (PDT) Received-SPF: pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=longman@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 57B723078AB5; Fri, 22 Mar 2019 14:35:23 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-47.bos.redhat.com [10.18.17.47]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8F7A219C59; Fri, 22 Mar 2019 14:35:18 +0000 (UTC) Subject: Re: [PATCH 4/4] mm: Do periodic rescheduling when freeing objects in kmem_free_up_q() To: Peter Zijlstra Cc: Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , linux-kernel@vger.kernel.org, linux-mm@kvack.org, selinux@vger.kernel.org, Paul Moore , Stephen Smalley , Eric Paris , Oleg Nesterov References: <20190321214512.11524-1-longman@redhat.com> <20190321214512.11524-5-longman@redhat.com> <20190321220035.GF7905@worktop.programming.kicks-ass.net> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFgsZGsBEAC3l/RVYISY3M0SznCZOv8aWc/bsAgif1H8h0WPDrHnwt1jfFTB26EzhRea XQKAJiZbjnTotxXq1JVaWxJcNJL7crruYeFdv7WUJqJzFgHnNM/upZuGsDIJHyqBHWK5X9ZO jRyfqV/i3Ll7VIZobcRLbTfEJgyLTAHn2Ipcpt8mRg2cck2sC9+RMi45Epweu7pKjfrF8JUY r71uif2ThpN8vGpn+FKbERFt4hW2dV/3awVckxxHXNrQYIB3I/G6mUdEZ9yrVrAfLw5M3fVU CRnC6fbroC6/ztD40lyTQWbCqGERVEwHFYYoxrcGa8AzMXN9CN7bleHmKZrGxDFWbg4877zX 0YaLRypme4K0ULbnNVRQcSZ9UalTvAzjpyWnlnXCLnFjzhV7qsjozloLTkZjyHimSc3yllH7 VvP/lGHnqUk7xDymgRHNNn0wWPuOpR97J/r7V1mSMZlni/FVTQTRu87aQRYu3nKhcNJ47TGY evz/U0ltaZEU41t7WGBnC7RlxYtdXziEn5fC8b1JfqiP0OJVQfdIMVIbEw1turVouTovUA39 Qqa6Pd1oYTw+Bdm1tkx7di73qB3x4pJoC8ZRfEmPqSpmu42sijWSBUgYJwsziTW2SBi4hRjU h/Tm0NuU1/R1bgv/EzoXjgOM4ZlSu6Pv7ICpELdWSrvkXJIuIwARAQABzR9Mb25nbWFuIExv bmcgPGxsb25nQHJlZGhhdC5jb20+wsF/BBMBAgApBQJYLGRrAhsjBQkJZgGABwsJCAcDAgEG FQgCCQoLBBYCAwECHgECF4AACgkQbjBXZE7vHeYwBA//ZYxi4I/4KVrqc6oodVfwPnOVxvyY oKZGPXZXAa3swtPGmRFc8kGyIMZpVTqGJYGD9ZDezxpWIkVQDnKM9zw/qGarUVKzElGHcuFN ddtwX64yxDhA+3Og8MTy8+8ZucM4oNsbM9Dx171bFnHjWSka8o6qhK5siBAf9WXcPNogUk4S fMNYKxexcUayv750GK5E8RouG0DrjtIMYVJwu+p3X1bRHHDoieVfE1i380YydPd7mXa7FrRl 7unTlrxUyJSiBc83HgKCdFC8+ggmRVisbs+1clMsK++ehz08dmGlbQD8Fv2VK5KR2+QXYLU0 rRQjXk/gJ8wcMasuUcywnj8dqqO3kIS1EfshrfR/xCNSREcv2fwHvfJjprpoE9tiL1qP7Jrq 4tUYazErOEQJcE8Qm3fioh40w8YrGGYEGNA4do/jaHXm1iB9rShXE2jnmy3ttdAh3M8W2OMK 4B/Rlr+Awr2NlVdvEF7iL70kO+aZeOu20Lq6mx4Kvq/WyjZg8g+vYGCExZ7sd8xpncBSl7b3 99AIyT55HaJjrs5F3Rl8dAklaDyzXviwcxs+gSYvRCr6AMzevmfWbAILN9i1ZkfbnqVdpaag QmWlmPuKzqKhJP+OMYSgYnpd/vu5FBbc+eXpuhydKqtUVOWjtp5hAERNnSpD87i1TilshFQm TFxHDzbOwU0EWCxkawEQALAcdzzKsZbcdSi1kgjfce9AMjyxkkZxcGc6Rhwvt78d66qIFK9D Y9wfcZBpuFY/AcKEqjTo4FZ5LCa7/dXNwOXOdB1Jfp54OFUqiYUJFymFKInHQYlmoES9EJEU yy+2ipzy5yGbLh3ZqAXyZCTmUKBU7oz/waN7ynEP0S0DqdWgJnpEiFjFN4/ovf9uveUnjzB6 lzd0BDckLU4dL7aqe2ROIHyG3zaBMuPo66pN3njEr7IcyAL6aK/IyRrwLXoxLMQW7YQmFPSw drATP3WO0x8UGaXlGMVcaeUBMJlqTyN4Swr2BbqBcEGAMPjFCm6MjAPv68h5hEoB9zvIg+fq M1/Gs4D8H8kUjOEOYtmVQ5RZQschPJle95BzNwE3Y48ZH5zewgU7ByVJKSgJ9HDhwX8Ryuia 79r86qZeFjXOUXZjjWdFDKl5vaiRbNWCpuSG1R1Tm8o/rd2NZ6l8LgcK9UcpWorrPknbE/pm MUeZ2d3ss5G5Vbb0bYVFRtYQiCCfHAQHO6uNtA9IztkuMpMRQDUiDoApHwYUY5Dqasu4ZDJk bZ8lC6qc2NXauOWMDw43z9He7k6LnYm/evcD+0+YebxNsorEiWDgIW8Q/E+h6RMS9kW3Rv1N qd2nFfiC8+p9I/KLcbV33tMhF1+dOgyiL4bcYeR351pnyXBPA66ldNWvABEBAAHCwWUEGAEC AA8FAlgsZGsCGwwFCQlmAYAACgkQbjBXZE7vHeYxSQ/+PnnPrOkKHDHQew8Pq9w2RAOO8gMg 9Ty4L54CsTf21Mqc6GXj6LN3WbQta7CVA0bKeq0+WnmsZ9jkTNh8lJp0/RnZkSUsDT9Tza9r GB0svZnBJMFJgSMfmwa3cBttCh+vqDV3ZIVSG54nPmGfUQMFPlDHccjWIvTvyY3a9SLeamaR jOGye8MQAlAD40fTWK2no6L1b8abGtziTkNh68zfu3wjQkXk4kA4zHroE61PpS3oMD4AyI9L 7A4Zv0Cvs2MhYQ4Qbbmafr+NOhzuunm5CoaRi+762+c508TqgRqH8W1htZCzab0pXHRfywtv 0P+BMT7vN2uMBdhr8c0b/hoGqBTenOmFt71tAyyGcPgI3f7DUxy+cv3GzenWjrvf3uFpxYx4 yFQkUcu06wa61nCdxXU/BWFItryAGGdh2fFXnIYP8NZfdA+zmpymJXDQeMsAEHS0BLTVQ3+M 7W5Ak8p9V+bFMtteBgoM23bskH6mgOAw6Cj/USW4cAJ8b++9zE0/4Bv4iaY5bcsL+h7TqQBH Lk1eByJeVooUa/mqa2UdVJalc8B9NrAnLiyRsg72Nurwzvknv7anSgIkL+doXDaG21DgCYTD wGA5uquIgb8p3/ENgYpDPrsZ72CxVC2NEJjJwwnRBStjJOGQX4lV1uhN1XsZjBbRHdKF2W9g weim8xU= Organization: Red Hat Message-ID: <2434d78c-b77c-571d-7add-e111f9d81485@redhat.com> Date: Fri, 22 Mar 2019 10:35:18 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190321220035.GF7905@worktop.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Fri, 22 Mar 2019 14:35:23 +0000 (UTC) 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 03/21/2019 06:00 PM, Peter Zijlstra wrote: > On Thu, Mar 21, 2019 at 05:45:12PM -0400, Waiman Long wrote: >> If the freeing queue has many objects, freeing all of them consecutively >> may cause soft lockup especially on a debug kernel. So kmem_free_up_q() >> is modified to call cond_resched() if running in the process context. >> >> Signed-off-by: Waiman Long >> --- >> mm/slab_common.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index dba20b4208f1..633a1d0f6d20 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -1622,11 +1622,14 @@ EXPORT_SYMBOL_GPL(kmem_free_q_add); >> * kmem_free_up_q - free all the objects in the freeing queue >> * @head: freeing queue head >> * >> - * Free all the objects in the freeing queue. >> + * Free all the objects in the freeing queue. The caller cannot hold any >> + * non-sleeping locks. >> */ >> void kmem_free_up_q(struct kmem_free_q_head *head) >> { >> struct kmem_free_q_node *node, *next; >> + bool do_resched = !in_irq(); >> + int cnt = 0; >> >> for (node = head->first; node; node = next) { >> next = node->next; >> @@ -1634,6 +1637,12 @@ void kmem_free_up_q(struct kmem_free_q_head *head) >> kmem_cache_free(node->cachep, node); >> else >> kfree(node); >> + /* >> + * Call cond_resched() every 256 objects freed when in >> + * process context. >> + */ >> + if (do_resched && !(++cnt & 0xff)) >> + cond_resched(); > Why not just: cond_resched() ? cond_resched() calls ___might_sleep(). So it is prudent to check for process context first to avoid erroneous message. Yes, I can call cond_resched() after every free. I added the count just to not call it too frequently. Cheers, Longman