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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9F518C3B187 for ; Wed, 12 Feb 2020 22:16:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 734852082F for ; Wed, 12 Feb 2020 22:16:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581545789; bh=xWKxGR9jZZLM8Fi96N9f70zttlqIrIjWLntWGvtmqaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=DWtfWiCbSGTZQIbu7ho4u1ME6huieC4nP3giZCZlw0uRTL45N3uMTxO7Kuo9oXH8R y5OSkjPLD2S+yHuMibkBnvzkTkjzZ69LfhH5cIXBAZgu7gen3vqcZVwj6GBPHxlOhk MRbXDIX+IPXv1ZD1trhw3XKpS5ojsDvRbzBB9qCQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729203AbgBLWQ2 (ORCPT ); Wed, 12 Feb 2020 17:16:28 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:39006 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727947AbgBLWQ0 (ORCPT ); Wed, 12 Feb 2020 17:16:26 -0500 Received: by mail-pg1-f195.google.com with SMTP id j15so1934888pgm.6 for ; Wed, 12 Feb 2020 14:16:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=D/5iSeGXxDP+lyJUNU19NRvUdswxslkbz5wrgabobm4=; b=RgghztW93FIsObaDVTciRjZtfHpXEir8OzbNJN4SLfBEcm0ZxYvARrdoRfoXg+LwMe jwiPMshiVt5Onf2q1iAfqMGoHt/WNe9/ARKxkJHYkx8V4VZQ/dzVrs3R+y43UPMVH6Gd rkB8L7CTQkylxONFx0N68n5Yt4bLQPcZj9G0Dg2dw1d9ksO8J5Gha2Ci5J2LEMK30HQO AzHycbYzANEqFI7IuT4k4eUWczU6MiwGLtqSos2qS+eaEfioQMTKAXhXKWFO4ifupbG3 E6/7183vg2hJ+yeMpUJh+q9TdtbUJbf+s9+wi9ObLW3GaWrcAfrc9g/LKACZVKX6dNzH g0kw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=D/5iSeGXxDP+lyJUNU19NRvUdswxslkbz5wrgabobm4=; b=oGsfzc/MKpkw+sL01j6LZp9696fMhiJQvmq7ZrRR6/qwdLZF/gqW9fno1BUqyZlshM rZ8YZIJuatCZZ3urnGXYPTwOMYeDYRAmtSHdmSG0hg6BoJyOgJzMNMf579C36bv680i9 QDNEQECWsiCHVNaqm8+ioiKj2EpEOXAXNnDzqgr9t/hlU6CV0hJ3sJAMJySZGq7FkZrH MXycJzQMF4MtuS6frwGby4u3vE0SSNNcDlsAWS3mqhBKzYWrv4+bsWgIZjcLqDQHL6Ua wFhLk69fj3SplyI2c253N3QfT4XngLX800qINlfXkUw4XmubtvDEIckjSwsJNll1l8vF VVxA== X-Gm-Message-State: APjAAAW68v0q510KzeWKUjSRcTfKMIBaypl9uGPHj8zdrugESxwNphUX x3uPNHx2/AjoKOVQ1V83bTI= X-Google-Smtp-Source: APXvYqz1nem2XDQSzeUCQA8Znbwsf82xp456uPoXIqYlQNqSSDiN2zIXgfgWRsDJA3ckF8qu9qTo7w== X-Received: by 2002:a63:42c4:: with SMTP id p187mr14713432pga.57.1581545785766; Wed, 12 Feb 2020 14:16:25 -0800 (PST) Received: from bbox-1.mtv.corp.google.com ([2620:15c:211:1:3e01:2939:5992:52da]) by smtp.gmail.com with ESMTPSA id o10sm117683pgq.68.2020.02.12.14.16.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Feb 2020 14:16:24 -0800 (PST) From: Minchan Kim To: Andrew Morton Cc: linux-mm , LKML , Jan Kara , Matthew Wilcox , Josef Bacik , Johannes Weiner , Minchan Kim , Robert Stupp Subject: [PATCH 3/3] mm: make PageReadahead more strict Date: Wed, 12 Feb 2020 14:16:14 -0800 Message-Id: <20200212221614.215302-3-minchan@kernel.org> X-Mailer: git-send-email 2.25.0.225.g125e21ebc7-goog In-Reply-To: <20200212221614.215302-1-minchan@kernel.org> References: <20200212221614.215302-1-minchan@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org PG_readahead flag is shared with PG_reclaim but PG_reclaim is only used in write context while PG_readahead is used for read context. To make it clear, let's introduce PageReadahead wrapper with !PageWriteback so it could make code clear and we could drop PageWriteback check in page_cache_async_readahead, which removes pointless dropping mmap_sem. Signed-off-by: Minchan Kim --- include/linux/page-flags.h | 28 ++++++++++++++++++++++++++-- mm/readahead.c | 6 ------ 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 1bf83c8fcaa7..f91a9b2a49bd 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -363,8 +363,32 @@ PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL) /* PG_readahead is only used for reads; PG_reclaim is only for writes */ PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) -PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) - TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND) + +SETPAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) +CLEARPAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND) + +/* + * Since PG_readahead is shared with PG_reclaim of the page flags, + * PageReadahead should double check whether it's readahead marker + * or PG_reclaim. It could be done by PageWriteback check because + * PG_reclaim is always with PG_writeback. + */ +static inline int PageReadahead(struct page *page) +{ + VM_BUG_ON_PGFLAGS(PageCompound(page), page); + + return (page->flags & (1UL << PG_reclaim | 1UL << PG_writeback)) == + (1UL << PG_reclaim); +} + +/* Clear PG_readahead only if it's PG_readahead, not PG_reclaim */ +static inline int TestClearPageReadahead(struct page *page) +{ + VM_BUG_ON_PGFLAGS(PageCompound(page), page); + + return !PageWriteback(page) || + test_and_clear_bit(PG_reclaim, &page->flags); +} #ifdef CONFIG_HIGHMEM /* diff --git a/mm/readahead.c b/mm/readahead.c index 2fe72cd29b47..85b15e5a1d7b 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -553,12 +553,6 @@ page_cache_async_readahead(struct address_space *mapping, if (!ra->ra_pages) return; - /* - * Same bit is used for PG_readahead and PG_reclaim. - */ - if (PageWriteback(page)) - return; - ClearPageReadahead(page); /* -- 2.25.0.225.g125e21ebc7-goog