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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 458C6C2BA19 for ; Tue, 14 Apr 2020 15:23:46 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EC2502063A for ; Tue, 14 Apr 2020 15:23:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mVT1NSNp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC2502063A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 491q5C3PFrzDqnp for ; Wed, 15 Apr 2020 01:23:43 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=willy@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=bombadil.20170209 header.b=mVT1NSNp; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 491pd25t9NzDqWq for ; Wed, 15 Apr 2020 01:02:46 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=wgHaMQ5NgsDKhTvfEwz+JAE6nlgMEKsX9P0uFTq8za0=; b=mVT1NSNp4+99ljtt8f5ensst1H BVN9ODww8/c4MKOX1APGFzeneBVLRxMFCc2GXaB3wFMrQtvT87NSC0nLVH4Ir7GVIADnlHy7ruhV9 d0vpxR70DyLbIhoPTYtmPAAb4YTMvpBUjtmFpAZmFQrAYzrbrHiUMmBebE8LE0QtToKrgBWhXWfl8 M57DLAhccVC9xC6vdxATVRnAzCSBZFBKkDZNxwlXvmpf9HutyUjq74veM+s5TR2/B6rIxfZiksWyV O6La15VtrLxkSJi6lyVR/jl/kkIIbv8f+Le7ZaSJJYx1c3rjAki3fFnbvWkmdr0RyHnInKmW1seFo OiLMGEOw==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jON5A-0006Ox-73; Tue, 14 Apr 2020 15:02:36 +0000 From: Matthew Wilcox To: Andrew Morton Subject: [PATCH v11 14/25] mm: Document why we don't set PageReadahead Date: Tue, 14 Apr 2020 08:02:22 -0700 Message-Id: <20200414150233.24495-15-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200414150233.24495-1-willy@infradead.org> References: <20200414150233.24495-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, William Kucharski , linux-kernel@vger.kernel.org, "Matthew Wilcox \(Oracle\)" , linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, Christoph Hellwig , linux-btrfs@vger.kernel.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" From: "Matthew Wilcox (Oracle)" If the page is already in cache, we don't set PageReadahead on it. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski --- mm/readahead.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index ae231a5312cb..73cb59ed5cff 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -195,9 +195,12 @@ void page_cache_readahead_unbounded(struct address_space *mapping, if (page && !xa_is_value(page)) { /* - * Page already present? Kick off the current batch of - * contiguous pages before continuing with the next - * batch. + * Page already present? Kick off the current batch + * of contiguous pages before continuing with the + * next batch. This page may be the one we would + * have intended to mark as Readahead, but we don't + * have a stable reference to this page, and it's + * not worth getting one just for that. */ read_pages(&rac, &page_pool, true); continue; -- 2.25.1