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 8EC9AC433F5 for ; Tue, 23 Nov 2021 17:59:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 104536B006C; Tue, 23 Nov 2021 12:59:36 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0B4466B0071; Tue, 23 Nov 2021 12:59:36 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EE5366B0072; Tue, 23 Nov 2021 12:59:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id DF24A6B006C for ; Tue, 23 Nov 2021 12:59:35 -0500 (EST) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id AB181824C43C for ; Tue, 23 Nov 2021 17:59:25 +0000 (UTC) X-FDA: 78840957174.01.3579A17 Received: from mail-lj1-f180.google.com (mail-lj1-f180.google.com [209.85.208.180]) by imf28.hostedemail.com (Postfix) with ESMTP id DA56090000BD for ; Tue, 23 Nov 2021 17:59:24 +0000 (UTC) Received: by mail-lj1-f180.google.com with SMTP id e11so12701415ljo.13 for ; Tue, 23 Nov 2021 09:59:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kZIuag7FlfW637npwI/iZ5O3Is51C1h2XYEt7gwhu2A=; b=Sj1jQbkuoPxjn7gutd7F17cEeO+GxHRH8PDVDtE09n/twk8V89GygKODfC7P0FVJdh xbPalhUApa7osyimYXaI2yRlmxrMiebFWJC0yqadJN1xLQ6tL/31IFJTT3006p7yO2be SYfoboBHLQKecVe9Xw8Goxe1PtPHMdw2C+RsbV7ajWbvb7QW1qxtTKqfLD1k3C7V6O6H gqZpsOcWyywSjtoYksuLA37bOioU5b7WY0m/ZBXg+SMB5NlBYohU02kUoBD2+jtsGDPv P4GFy9NxLI6PRlNDHuMIXLXDNEOCvju2Msqff7Od5i7ncneddLYjadA+ZUFUUs9ajPPB dAkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kZIuag7FlfW637npwI/iZ5O3Is51C1h2XYEt7gwhu2A=; b=UILBWY7vcnXWUqJ0gDya6xDTmYugsEwvi5SogoTcWaSA/uI2VuVi0jQt+YBrjMnAKs UnPJd71PH2bk9cy+XmMY+HJJCxeusferVEpG6cWuw3gi0T4QE+s8chauktCbjQoGszYD ImLEbWCFJaqznGbsUY1drG3HyB1XH/g7lDKAYjelrxkYJwAQPJ7uZ0oA3YsdBW5AncY2 J6cyMwUz6cK+5tOiQZ0zQ+x4+Nl6bcOwGhK0U1lAjAYt/n8h/2sDOJPQTcRyBikPc0QU CgLqtqMRiQ1b+BlkM2ZF5UN+NW9yDUz3dCJzHvIoYFEIun8eJlMNCOjk4CNAYPUODOLp kTIA== X-Gm-Message-State: AOAM530lmsf7/+TUV3oqGPRLe/ZqJhNxY1RL26pf77ZF6hzYpvbkj7A/ QahA85QFOv9Z+nIRLiMZuoq1KrXpalBdc8qeCQE92w== X-Google-Smtp-Source: ABdhPJxFAaFB+oZdm/wfRdcVzSUxvKp9cPNqY1LD8fy90cgI+qVrlWoNl9q1CthNkuAKDNHKcULvvUTUyOwCf6jMfgs= X-Received: by 2002:a05:651c:545:: with SMTP id q5mr7162702ljp.202.1637690363016; Tue, 23 Nov 2021 09:59:23 -0800 (PST) MIME-Version: 1.0 References: <20211123174658.1728753-1-shakeelb@google.com> In-Reply-To: <20211123174658.1728753-1-shakeelb@google.com> From: Shakeel Butt Date: Tue, 23 Nov 2021 09:59:11 -0800 Message-ID: Subject: Re: [PATCH] mm: thp: update split_queue_len correctly To: David Hildenbrand , "Kirill A . Shutemov" , Yang Shi , Zi Yan , Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: kfgm6fnqdwsscs8o6xuiasotjwiw9r4p Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Sj1jQbku; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf28.hostedemail.com: domain of shakeelb@google.com designates 209.85.208.180 as permitted sender) smtp.mailfrom=shakeelb@google.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: DA56090000BD X-HE-Tag: 1637690364-412922 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, Nov 23, 2021 at 9:47 AM Shakeel Butt wrote: > > The deferred THPs are split on memory pressure through shrinker > callback and splitting of THP during reclaim can fail for several > reasons like unable to lock the THP, under writeback or unexpected > number of pins on the THP. Such pages are put back on the deferred split > list for consideration later. However kernel does not update the > deferred queue size on putting back the pages whose split was failed. > This patch fixes that. I forgot to add the user visible impact. "Without this patch the split_queue_len can underflow. Shrinker will always get that there are some THPs to split even if there are not and waste some cpu to scan the empty list."