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=-12.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9A8B6C4320E for ; Mon, 30 Aug 2021 09:11:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0D7A961038 for ; Mon, 30 Aug 2021 09:11:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0D7A961038 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 1663B6B006C; Mon, 30 Aug 2021 05:11:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 116776B0071; Mon, 30 Aug 2021 05:11:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0051E8D0001; Mon, 30 Aug 2021 05:11:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0161.hostedemail.com [216.40.44.161]) by kanga.kvack.org (Postfix) with ESMTP id E2C2F6B006C for ; Mon, 30 Aug 2021 05:11:08 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8364E20BE3 for ; Mon, 30 Aug 2021 09:11:08 +0000 (UTC) X-FDA: 78531177816.17.5BA38CE Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf30.hostedemail.com (Postfix) with ESMTP id 0B04CE0016BB for ; Mon, 30 Aug 2021 09:11:07 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id AD9342210A; Mon, 30 Aug 2021 09:11:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1630314666; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=u9PHrKLeF/G92NZinwTPYi6Jk6TfyNGd5chLk0Q8RQw=; b=K+blWjJcwt1t6ZUxLw4mt6iY/X3AYSEpp+NgugaOuXgmjzDCUYli0wwrMc5ibDdmGsskje q7ovXoWsoNBgUQERrN98XxrPqK+VyMYtgLw5X07pYm6oM1djM8NFrRDMWmpXoLsO/vhY1J lg/OQ4n38Mu2nTZd0iXndKwD7cBPvNk= Received: from suse.com (unknown [10.163.43.106]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 60D45A3B9D; Mon, 30 Aug 2021 09:11:06 +0000 (UTC) Date: Mon, 30 Aug 2021 10:11:04 +0100 From: Mel Gorman To: NeilBrown Cc: Chuck Lever III , Mike Javorski , Linux NFS Mailing List , linux-mm@kvack.org Subject: Re: [PATCH] MM: clarify effort used in alloc_pages_bulk_*() Message-ID: <20210830091104.GA3997@suse.com> References: <163004202961.7591.12633163545286005205@noble.neil.brown.name> <163004848514.7591.2757618782251492498@noble.neil.brown.name> <6CC9C852-CEE3-4657-86AD-9D5759E2BE1C@oracle.com> <416268C9-BEAC-483C-9392-8139340BC849@oracle.com> <12B831AA-4A4E-4102-ADA3-97B6FA0B119E@oracle.com> <163027609524.7591.4987241695872857175@noble.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <163027609524.7591.4987241695872857175@noble.neil.brown.name> User-Agent: Mutt/1.10.1 (2018-07-13) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=K+blWjJc; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf30.hostedemail.com: domain of mgorman@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mgorman@suse.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 0B04CE0016BB X-Stat-Signature: qscpfyzmwhwrcaenb95unhxxhbtazuxr X-HE-Tag: 1630314667-149949 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: On Mon, Aug 30, 2021 at 08:28:15AM +1000, NeilBrown wrote: > > The alloc_pages_bulk_*() interfaces do not make it clear what degree > of success can be expected. > > The code appears to allocate at least one page with the same effort as > alloc_page() when used with the same GFP flags, and then to allocate any > more only opportunistically. So a caller should not *expect* to get a > full allocation, but should not be *surprised* by one either. > > Add text to the comment clarifying this. > > Also fix a bug. 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. > > Fixes: 0f87d9d30f21 ("mm/page_alloc: add an array-based interface to the bulk page allocator") > Signed-off-by: NeilBrown Acked-by: Mel Gorman -- Mel Gorman SUSE Labs