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=-11.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 29050C433E0 for ; Tue, 5 Jan 2021 07:05:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8A0F922482 for ; Tue, 5 Jan 2021 07:05:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A0F922482 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9622A8D0057; Tue, 5 Jan 2021 02:05:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8EA968D0036; Tue, 5 Jan 2021 02:05:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 763FE8D0057; Tue, 5 Jan 2021 02:05:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0166.hostedemail.com [216.40.44.166]) by kanga.kvack.org (Postfix) with ESMTP id 5C46E8D0036 for ; Tue, 5 Jan 2021 02:05:50 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1CDDA180AD80F for ; Tue, 5 Jan 2021 07:05:50 +0000 (UTC) X-FDA: 77670836460.22.scene95_36062f3274d7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id EE07818038E60 for ; Tue, 5 Jan 2021 07:05:49 +0000 (UTC) X-HE-Tag: scene95_36062f3274d7 X-Filterd-Recvd-Size: 4537 Received: from so254-31.mailgun.net (so254-31.mailgun.net [198.61.254.31]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 Jan 2021 07:05:46 +0000 (UTC) DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1609830348; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=2RibZ3quCogr3Bv7+yL4XndtnXP1rZOfy3IGjqSqr84=; b=cvvIRwQT2kst/WovqF93Revfwufol+IS1wAIPl/MYwe3fQHuHOErflLPPzkuq6ra2WV5Wzzy 1Re87qoAvfLxD/OpDpwiyPi+R10zbjRIa8agZ4Uz/xn+rswypFDzbPegg1TQrdcUfkrWP4vQ Q1fpynBUyq2M5AcwGl3P5CcTtVo= X-Mailgun-Sending-Ip: 198.61.254.31 X-Mailgun-Sid: WyIwY2Q3OCIsICJsaW51eC1tbUBrdmFjay5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n08.prod.us-east-1.postgun.com with SMTP id 5ff40fc600a8b472192fe053 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 05 Jan 2021 07:05:42 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 75C25C433C6; Tue, 5 Jan 2021 07:05:41 +0000 (UTC) Received: from cgoldswo-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: cgoldswo) by smtp.codeaurora.org (Postfix) with ESMTPSA id 62A6BC433C6; Tue, 5 Jan 2021 07:05:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 62A6BC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=cgoldswo@codeaurora.org From: Chris Goldsworthy To: Alexander Viro , linux-fsdevel@vger.kernel.org, Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Chris Goldsworthy Subject: [PATCH v2] Resolve LRU page-pinning issue for file-backed pages Date: Mon, 4 Jan 2021 23:05:32 -0800 Message-Id: X-Mailer: git-send-email 2.7.4 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: It is possible for file-backed pages to end up in a contiguous memory area (CMA), such that the relevant page must be migrated using the .migratepage() callback when its backing physical memory is selected for use in an CMA allocation (through cma_alloc()). However, if a set of address space operations (AOPs) for a file-backed page lacks a migratepage() page call-back, fallback_migrate_page() will be used instead, which through try_to_release_page() calls try_to_free_buffers() (which is called directly or through a try_to_free_buffers() callback. try_to_free_buffers() in turn calls drop_buffers() drop_buffers() itself can fail due to the buffer_head associated with a page being busy. However, it is possible that the buffer_head is on an LRU list for a CPU, such that we can try removing the buffer_head from that list, in order to successfully release the page. Do this. v1: https://lore.kernel.org/lkml/cover.1606194703.git.cgoldswo@codeaurora.org/T/#m3a44b5745054206665455625ccaf27379df8a190 Original version of the patch (with updates to make to account for changes in on_each_cpu_cond()). v2: Follow Matthew Wilcox's suggestion of reducing the number of calls to on_each_cpu_cond(), by iterating over a page's busy buffer_heads inside of on_each_cpu_cond(). To copy from his e-mail, we go from: for_each_buffer for_each_cpu for_each_lru_entry to: for_each_cpu for_each_buffer for_each_lru_entry This is done using xarrays, which I found to be the cleanest data structure to use, though a pre-allocated array of page_size(page) / bh->b_size elements might be more performant. Laura Abbott (1): fs/buffer.c: Revoke LRU when trying to drop buffers fs/buffer.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++---- fs/internal.h | 5 ++++ 2 files changed, 85 insertions(+), 5 deletions(-) -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project