From patchwork Fri Sep 17 02:56:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12500873 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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 541D0C433EF for ; Fri, 17 Sep 2021 02:59:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E8802611C8 for ; Fri, 17 Sep 2021 02:59:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E8802611C8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 8492D6B0072; Thu, 16 Sep 2021 22:59:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7F90C6B0073; Thu, 16 Sep 2021 22:59:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6C113900002; Thu, 16 Sep 2021 22:59:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0066.hostedemail.com [216.40.44.66]) by kanga.kvack.org (Postfix) with ESMTP id 5E9A66B0072 for ; Thu, 16 Sep 2021 22:59:31 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 10E5830C97 for ; Fri, 17 Sep 2021 02:59:31 +0000 (UTC) X-FDA: 78595559742.28.5F130D3 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf12.hostedemail.com (Postfix) with ESMTP id A34EB10000B4 for ; Fri, 17 Sep 2021 02:59:30 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id ABA7D2007B; Fri, 17 Sep 2021 02:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631847569; h=from:from:reply-to: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; bh=PhO+AMBCn5CF5KJqwHi2NRgoifLeDG6tBD6IhB9YLqI=; b=vThorR8aWQ88Y2GmJEKKlzu9235Z/ZeCUkMr1tu37GhRXPpZfoOnsprc1JRFJTuXWRqbYo OrwNdG+winpkkSlgaBUSLsVjiQSK1WiUbcsFBMP1c4iGoCvNYpDkYEriFSvFrODR8idE2j Tlusg86Y9/ATaenPc/okC73RyP3RPU0= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631847569; h=from:from:reply-to: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; bh=PhO+AMBCn5CF5KJqwHi2NRgoifLeDG6tBD6IhB9YLqI=; b=PdD7iVhth5i0uczJ3IGRe4R+iuVLNQA6JKSOCFB6xykfVbdQIAbKb0z9L556d52BZHWlwR comcujPIZxeGDSBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 4A36E13D0B; Fri, 17 Sep 2021 02:59:25 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id v4HZAo0ERGFmMwAAMHmgww (envelope-from ); Fri, 17 Sep 2021 02:59:25 +0000 Subject: [PATCH 1/6] MM: Support __GFP_NOFAIL in alloc_pages_bulk_*() and improve doco From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman , Michal Hocko , ". Dave Chinner" , Jonathan Corbet Cc: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Date: Fri, 17 Sep 2021 12:56:57 +1000 Message-ID: <163184741776.29351.3565418361661850328.stgit@noble.brown> In-Reply-To: <163184698512.29351.4735492251524335974.stgit@noble.brown> References: <163184698512.29351.4735492251524335974.stgit@noble.brown> User-Agent: StGit/0.23 MIME-Version: 1.0 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=vThorR8a; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=PdD7iVht; spf=pass (imf12.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-Stat-Signature: 5e9sa1t3fthhxurp6mssrotznn17g9aj X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A34EB10000B4 X-HE-Tag: 1631847570-984204 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: When alloc_pages_bulk_array() is called on an array that is partially allocated, the level of effort to get a single page is less than when the array was completely unallocated. This behaviour is inconsistent, but now fixed. One effect if this is that __GFP_NOFAIL will not ensure at least one page is allocated. Also clarify the expected success rate. __alloc_pages_bulk() will allocated one page according to @gfp, and may allocate more if that can be done cheaply. It is assumed that the caller values cheap allocation where possible and may decide to use what it has got, or to call again to get more. Acked-by: Mel Gorman Fixes: 0f87d9d30f21 ("mm/page_alloc: add an array-based interface to the bulk page allocator") Signed-off-by: NeilBrown --- mm/page_alloc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index b37435c274cf..aa51016e49c5 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5191,6 +5191,11 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, * is the maximum number of pages that will be stored in the array. * * Returns the number of pages on the list or array. + * + * At least one page will be allocated if that is possible while + * remaining consistent with @gfp. Extra pages up to the requested + * total will be allocated opportunistically when doing so is + * significantly cheaper than having the caller repeat the request. */ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, nodemask_t *nodemask, int nr_pages, @@ -5292,7 +5297,7 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, pcp, pcp_list); if (unlikely(!page)) { /* Try and get at least one page */ - if (!nr_populated) + if (!nr_account) goto failed_irq; break; }