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=-9.5 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=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 90B7FC5ACC5 for ; Wed, 19 Feb 2020 21:01:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 537F6207FD for ; Wed, 19 Feb 2020 21:01:09 +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="Rr0Isn6K" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 537F6207FD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 933E46B000D; Wed, 19 Feb 2020 16:01:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8B8FB6B000A; Wed, 19 Feb 2020 16:01:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7597D6B000D; Wed, 19 Feb 2020 16:01:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0245.hostedemail.com [216.40.44.245]) by kanga.kvack.org (Postfix) with ESMTP id 46A1C6B0006 for ; Wed, 19 Feb 2020 16:01:07 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 103C345AA for ; Wed, 19 Feb 2020 21:01:07 +0000 (UTC) X-FDA: 76508096574.13.hen37_9ae058ce5e0c X-HE-Tag: hen37_9ae058ce5e0c X-Filterd-Recvd-Size: 2888 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Wed, 19 Feb 2020 21:01:06 +0000 (UTC) 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=8zYEi4IG7gzAvMHdDHY3fStOc4dh5wVqKWm99G/lD2Q=; b=Rr0Isn6KV0yiQsuTepKXa8KVhx +JyO+IlvzFzA0z8sV2iMvtsm9Pv6cgJBZMIpSg1cP4Tx/ZMk08ueKIw29L1ptgphnFq+2Q+86II+5 PJNKMmaiCDdBTTJcDI/iXmLXg84N2WswF5/urdiVm5BTv6ykoK2n3od2eyCx5s1P6nY1KF4YFoSKI volIkWq8cBw6eiWFrgoZdNhCO9tAL9ZiLKXZMPI9znsj3s/nMwWW9pTQdBxelt0H9avPXVOec5UVz t7L9I6CkSyQomfI4fzLa6hPYbkKOJATGVMcI+Zu0LuHW7aFhXW23e3VE3cpt3VyFwn6ldkAqvOfZV bM3ipe0w==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4WSv-0008VZ-JM; Wed, 19 Feb 2020 21:01:05 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org Subject: [PATCH v7 23/24] mm: Document why we don't set PageReadahead Date: Wed, 19 Feb 2020 13:01:02 -0800 Message-Id: <20200219210103.32400-24-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200219210103.32400-1-willy@infradead.org> References: <20200219210103.32400-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: From: "Matthew Wilcox (Oracle)" If the page is already in cache, we don't set PageReadahead on it. Signed-off-by: Matthew Wilcox (Oracle) --- mm/readahead.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 453ef146de83..bbe7208fcc2d 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -196,9 +196,12 @@ void page_cache_readahead_unbounded(struct address_s= pace *mapping, =20 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); continue; --=20 2.25.0