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 63EFEC433EF for ; Sat, 2 Jul 2022 01:56:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 578A86B0071; Fri, 1 Jul 2022 21:56:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 528936B0073; Fri, 1 Jul 2022 21:56:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3EF566B0074; Fri, 1 Jul 2022 21:56:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 312346B0071 for ; Fri, 1 Jul 2022 21:56:56 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id EBA65205AC for ; Sat, 2 Jul 2022 01:56:55 +0000 (UTC) X-FDA: 79640496390.06.BB5D309 Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) by imf15.hostedemail.com (Postfix) with ESMTP id 50434A003C for ; Sat, 2 Jul 2022 01:56:55 +0000 (UTC) Received: by mail-pl1-f182.google.com with SMTP id r1so3881717plo.10 for ; Fri, 01 Jul 2022 18:56:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=F0XSM8WepbLbncY9Jh1o5a8Ab7/D83rCnVI+VO9kzyQ=; b=iNAKNCMaS08lo7ToSrGJdN+MK46yTsNYSJilnnEtNB1vk3A91gn2OEqzYtqaAUzDhU V8bmb/fGxYgMgGzA3jQ1CGL7FZtEe/wWJuJ0zQIC0rKnEIheWBiGrv1uX6MLdhkUUwH2 DbwdhQMzf61QihOiZMu0GEs5P3tfrEbpaaqSgK1Re7GhM302mfVQAdcm8YTS2u1W5ExJ 5nCn7Q+H0fRzW7NQnJxSEx03b4yTuHYMXTvNC/w9lSsRbpNGp68dTrrHQBBa36DZhqp0 0tXDz0Z7beLDm9Of2QCyChghvRn+RyHsgKxfLo2dJ/Ck13X9dzKnqEZMbHlOtEthmBB2 A/Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=F0XSM8WepbLbncY9Jh1o5a8Ab7/D83rCnVI+VO9kzyQ=; b=QpBFqbUbQhYiOr0501NIHbWVyaUSa6Gt+00IsUgPRDwpRXXtGnpEie/w5rWtooZk0u e/UVDXfRbGSk8OOQniUeM3tFoHb1eTqrYykdOk/ePJYEd9xhXxR40DbYvH1AmnEzq0nO Mbxk5qgMHoc8yMyLg5YKROD3VQyEPrk0Xb2c6BzfZDzHZxIgXyhEY/iVbmPUtnpUQ0WY PjM2SPvWwIJ+fHHUhwx0PY+TloNxwPZe+zYTGHIKntIpmt/xWElGQsoJlQmc+VAavmJE 3vlHqBT8OC0okb9ksxj30BfljDRiNddmQZrK1TO5t23T9uN2mUoV3JdmlUR23VvhBWQJ op5w== X-Gm-Message-State: AJIora/uxuxdb8Rwb999mN5T0z/8ie9gNdeSJTcvya1ASJYaBjBQbX3G YqRBNlPwgdUnB+e4YgSlyVBVBOVaULsqlA== X-Google-Smtp-Source: AGRyM1ueFEHk2V8vZtftceZ1/EM0t2iJG+x9BOdZtbe7eRiL0IVJLhkSK1HkpkewVHV5C/DP5a8mGQ== X-Received: by 2002:a17:902:ab8a:b0:16a:4521:a7b7 with SMTP id f10-20020a170902ab8a00b0016a4521a7b7mr23812000plr.57.1656727013962; Fri, 01 Jul 2022 18:56:53 -0700 (PDT) Received: from smtpclient.apple ([2600:380:b432:82c5:b571:4ad9:6687:7adb]) by smtp.gmail.com with ESMTPSA id e17-20020a63ee11000000b004119deff40dsm4539451pgi.23.2022.07.01.18.56.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Jul 2022 18:56:53 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Jens Axboe Mime-Version: 1.0 (1.0) Subject: Re: [PATCH] mm: honor FGP_NOWAIT for page cache page allocation Date: Fri, 1 Jul 2022 19:56:51 -0600 Message-Id: <48E589E0-094C-43F2-A6CE-714EAF9EC153@kernel.dk> References: <20220702005634.zsrvwkxc7ghsedxk@google.com> Cc: Matthew Wilcox , linux-mm@kvack.org, Stefan Roesch In-Reply-To: <20220702005634.zsrvwkxc7ghsedxk@google.com> To: Shakeel Butt X-Mailer: iPhone Mail (19F77) ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=kernel-dk.20210112.gappssmtp.com header.s=20210112 header.b=iNAKNCMa; dmarc=none; spf=pass (imf15.hostedemail.com: domain of axboe@kernel.dk designates 209.85.214.182 as permitted sender) smtp.mailfrom=axboe@kernel.dk ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656727015; a=rsa-sha256; cv=none; b=ozV24tE+rnEc0WgXv1VQHZEe+vV6IkJLO+KdHgOrLlzlMvQGR1JiUyYkPgDibrwRgvc7jD FI7A709/On1Y1m1fN6ISUAV9dvNrggG05ISOpmT1xIoMdGIA2RKTaVWbY2QIrDciwIaOXM aWBiNaco5b0xWItNX9VUZPQSHvJeguU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656727015; 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=F0XSM8WepbLbncY9Jh1o5a8Ab7/D83rCnVI+VO9kzyQ=; b=cU70Nt7iGKr97FpScUjRysqPbtImBcvAwBtf4F2LmTbpen2m7G/ryrzdszyvvuDtKRjXlw 8iK4c2sSQQYxrzymk8wbdwcuad0MzM/K4kLpy9GNXKOrchtXB/kTnY6dyehwlcIhEBtmZq xoV9vikSxBI2OMbcT0yaXAxVnk2j6vk= X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=kernel-dk.20210112.gappssmtp.com header.s=20210112 header.b=iNAKNCMa; dmarc=none; spf=pass (imf15.hostedemail.com: domain of axboe@kernel.dk designates 209.85.214.182 as permitted sender) smtp.mailfrom=axboe@kernel.dk X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 50434A003C X-Stat-Signature: dixkg9prfk95px73yk61nsotxapagc4y X-HE-Tag: 1656727015-978026 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 Jul 1, 2022, at 6:56 PM, Shakeel Butt wrote: >=20 > =EF=BB=BFOn Fri, Jul 01, 2022 at 02:08:26PM -0600, Jens Axboe wrote: >> If we're creating a page cache page with FGP_CREAT but FGP_NOWAIT is >> set, we should dial back the gfp flags to avoid frivolous blocking >> which is trivial to hit in low memory conditions: >>=20 >> [ 10.117661] __schedule+0x8c/0x550 >> [ 10.118305] schedule+0x58/0xa0 >> [ 10.118897] schedule_timeout+0x30/0xdc >> [ 10.119610] __wait_for_common+0x88/0x114 >> [ 10.120348] wait_for_completion+0x1c/0x24 >> [ 10.121103] __flush_work.isra.0+0x16c/0x19c >> [ 10.121896] flush_work+0xc/0x14 >> [ 10.122496] __drain_all_pages+0x144/0x218 >> [ 10.123267] drain_all_pages+0x10/0x18 >> [ 10.123941] __alloc_pages+0x464/0x9e4 >> [ 10.124633] __folio_alloc+0x18/0x3c >> [ 10.125294] __filemap_get_folio+0x17c/0x204 >> [ 10.126084] iomap_write_begin+0xf8/0x428 >> [ 10.126829] iomap_file_buffered_write+0x144/0x24c >> [ 10.127710] xfs_file_buffered_write+0xe8/0x248 >> [ 10.128553] xfs_file_write_iter+0xa8/0x120 >> [ 10.129324] io_write+0x16c/0x38c >> [ 10.129940] io_issue_sqe+0x70/0x1cc >> [ 10.130617] io_queue_sqe+0x18/0xfc >> [ 10.131277] io_submit_sqes+0x5d4/0x600 >> [ 10.131946] __arm64_sys_io_uring_enter+0x224/0x600 >> [ 10.132752] invoke_syscall.constprop.0+0x70/0xc0 >> [ 10.133616] do_el0_svc+0xd0/0x118 >> [ 10.134238] el0_svc+0x78/0xa0 >>=20 >> Clear IO, FS, and reclaim flags and mark the allocation as nowarn, >> as FGP_NOWAIT are expected to be able to handle -EAGAIN failures and >> retry from a suitable context without NOWAIT set. >>=20 >> Signed-off-by: Jens Axboe >> --- >> mm/filemap.c | 4 ++++ >> 1 file changed, 4 insertions(+) >>=20 >> diff --git a/mm/filemap.c b/mm/filemap.c >> index ffdfbc8b0e3c..9b747d3247c6 100644 >> --- a/mm/filemap.c >> +++ b/mm/filemap.c >> @@ -1988,6 +1988,10 @@ struct folio *__filemap_get_folio(struct address_s= pace *mapping, pgoff_t index, >> gfp |=3D __GFP_WRITE; >> if (fgp_flags & FGP_NOFS) >> gfp &=3D ~__GFP_FS; >> + if (fgp_flags & FGP_NOWAIT) { >> + gfp &=3D ~GFP_KERNEL; >=20 > Do you think the semantic of FGP_NOWAIT should be similar to GFP_NOWAIT? > That is allow kswapd wakeup. Yep I think that=E2=80=99d be fine, and probably appropriate.