From patchwork Tue Apr 14 15:02:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11488015 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2152814DD for ; Tue, 14 Apr 2020 15:03:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E28A22078B for ; Tue, 14 Apr 2020 15:03:17 +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 E28A22078B 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 40AF68E0012; Tue, 14 Apr 2020 11:02:43 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 3BAA78E000B; Tue, 14 Apr 2020 11:02:43 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2132F8E0018; Tue, 14 Apr 2020 11:02:43 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0102.hostedemail.com [216.40.44.102]) by kanga.kvack.org (Postfix) with ESMTP id D9DE58E0012 for ; Tue, 14 Apr 2020 11:02:42 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9A423180AD811 for ; Tue, 14 Apr 2020 15:02:42 +0000 (UTC) X-FDA: 76706777364.01.drug07_51d49afb0234d X-Spam-Summary: 2,0,0,e13374ba0aa7b231,d41d8cd98f00b204,willy@infradead.org,,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1311:1314:1345:1359:1437:1515:1534:1541:1711:1730:1747:1777:1792:2393:2553:2559:2562:2898:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3870:3871:3872:3874:5007:6120:6261:6653:6742:7576:7901:8957:10004:11026:11658:11914:12043:12296:12297:12438:12555:12895:13069:13311:13357:13894:14096:14181:14384:14394:14721:21063:21080:21451:21627:30054:30064:30070:30090,0,RBL:198.137.202.133:@infradead.org:.lbl8.mailshell.net-64.201.201.201 62.8.0.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:25,LUA_SUMMARY:none X-HE-Tag: drug07_51d49afb0234d X-Filterd-Recvd-Size: 3134 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Apr 2020 15:02:42 +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=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 Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, 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, Christoph Hellwig , William Kucharski 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 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) 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;