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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0704FC76196 for ; Thu, 6 Apr 2023 07:25:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5A79F6B0071; Thu, 6 Apr 2023 03:25:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 558486B0074; Thu, 6 Apr 2023 03:25:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F8A86B0075; Thu, 6 Apr 2023 03:25:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 303856B0071 for ; Thu, 6 Apr 2023 03:25:40 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id D33C11A0EFC for ; Thu, 6 Apr 2023 07:25:39 +0000 (UTC) X-FDA: 80650131198.06.C7E4642 Received: from wout4-smtp.messagingengine.com (wout4-smtp.messagingengine.com [64.147.123.20]) by imf28.hostedemail.com (Postfix) with ESMTP id 1D0BBC0005 for ; Thu, 6 Apr 2023 07:25:35 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=shutemov.name header.s=fm1 header.b="p hoIvuJ"; dkim=pass header.d=messagingengine.com header.s=fm2 header.b=rjCICZv6; spf=pass (imf28.hostedemail.com: domain of kirill@shutemov.name designates 64.147.123.20 as permitted sender) smtp.mailfrom=kirill@shutemov.name; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1680765936; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=mSLRY4bfvs6q0sv5lAC5YPzV1A9nS5DmWiDXnI5elus=; b=3X+j29eTarq82sRCJZGDkwGCjzHgqtvUNUIAnGNRbtu2pknvrzfqraUvpRjroCH58EPbwV rrTZvVsgXR9zA+YtV8JZQDMgm10RqTx9ChP2IJMuztVPATO5uB/sKwik4UUURitynHDgnt GhPzhV/5vYb+rWqlbIN53eBom2L0hWQ= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=shutemov.name header.s=fm1 header.b="p hoIvuJ"; dkim=pass header.d=messagingengine.com header.s=fm2 header.b=rjCICZv6; spf=pass (imf28.hostedemail.com: domain of kirill@shutemov.name designates 64.147.123.20 as permitted sender) smtp.mailfrom=kirill@shutemov.name; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680765936; a=rsa-sha256; cv=none; b=zYpi/0/ZJdZGIi4Fexs6migyi8pkR8HrTigUNUb9zwInFfONDF1ofaiGmuEEDBBgCws/8x p7xstLPOu+r6RyTCve8aRrJBvX7XtRHrNfyoS43UDbzISEZHLFE2TvODQBsSLLdTPO8jut Dg/gZdPL4iV8ll6RI/a9Om53jeVo0XQ= Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 19C283200985; Thu, 6 Apr 2023 03:25:34 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Thu, 06 Apr 2023 03:25:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov.name; h=cc:cc:content-type:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to; s=fm1; t=1680765933; x= 1680852333; bh=mSLRY4bfvs6q0sv5lAC5YPzV1A9nS5DmWiDXnI5elus=; b=p hoIvuJvyXTomJUNCECIoOND4embs/OFpe127VUY/w8ay9PKck4ZKFAW6LEbc5Eyr PNVyQglyJlXNUvGQA/vacOJnKDYmAorJqSVw0tWeDUrIUIootVofjPseG44ZJanb 6/s9Ui+Ze8Js09VOcli3fwnEpq4r5aydj/5abdR8vcYnexR4sS7o3cbUOK8jt5Qx dCNIY+CvOR3xwM6L7HWimGz2J5GYwPDjlSdw0RcofXR7qYDeve7P9MJtSnL4tnHN jkRtnvCO+EQpeEn7j7kxTXMAxgIb/FDJbb3tJTKSJHq7nrEW2dU+fKtKo6ltRCch IMeL82vBKjoUzedAx7XqQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm2; t=1680765933; x=1680852333; bh=mSLRY4bfvs6q0 sv5lAC5YPzV1A9nS5DmWiDXnI5elus=; b=rjCICZv68UQ8//r6X+ggawcCbpcC0 eo2KC0pdHFLhejjC5YWUako56WK0k3zCHMaoEOamdjMw00AvNpoRDNutztoIihCi RlXEkKSV50mN6HeQerGO/cLVShelTTgBpwt0o5mG8a+V4/1B9QzHaID/itAOlNZo +MAjCDtlPgPWALPs/xlPMsdaC2Y+FLPrG6HkZNMtYaMKuh5NUc2esnq8A97OTgjo r5lb5Og8BKRcm83UrzXi/yfqEQajWZjuzTsZsqBQqLJKxLXY8GPA6kbMHOJwlSxf 8pZ7jHh83zUyVQJUcUNNr7Wl+K6bKDjSWgxYvuihv6qzETH9+3F0oyV1w== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvdejvddguddvudcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecunecujfgurhepfffhvfevuffkfhggtggujgesth dttddttddtvdenucfhrhhomhepfdfmihhrihhllhcutedrucfuhhhuthgvmhhovhdfuceo khhirhhilhhlsehshhhuthgvmhhovhdrnhgrmhgvqeenucggtffrrghtthgvrhhnpeelgf fhfeetlefhveffleevfffgtefffeelfeduudfhjeduteeggfeiheefteehjeenucffohhm rghinhepkhgvrhhnvghlrdhorhhgnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrg hmpehmrghilhhfrhhomhepkhhirhhilhhlsehshhhuthgvmhhovhdrnhgrmhgv X-ME-Proxy: Feedback-ID: ie3994620:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 6 Apr 2023 03:25:33 -0400 (EDT) Received: by box.shutemov.name (Postfix, from userid 1000) id BEF80102846; Thu, 6 Apr 2023 10:25:29 +0300 (+03) Date: Thu, 6 Apr 2023 10:25:29 +0300 From: "Kirill A. Shutemov" To: Guenter Roeck Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm-treewide-redefine-max_order-sanely-fix.txt Message-ID: <20230406072529.vupqyrzqnhyozeyh@box.shutemov.name> References: <9460377a-38aa-4f39-ad57-fb73725f92db@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9460377a-38aa-4f39-ad57-fb73725f92db@roeck-us.net> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1D0BBC0005 X-Rspam-User: X-Stat-Signature: 5ef8dkhffu857bwjumi3yky6gwnz646c X-HE-Tag: 1680765935-77526 X-HE-Meta: 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 2cOoVJvb 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 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 Wed, Apr 05, 2023 at 10:20:26PM -0700, Guenter Roeck wrote: > Hi, > > On Wed, Mar 15, 2023 at 06:38:00PM +0300, Kirill A. Shutemov wrote: > > fix min() warning > > > > Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box > > Reported-by: kernel test robot > > Link: https://lore.kernel.org/oe-kbuild-all/202303152343.D93IbJmn-lkp@intel.com/ > > Signed-off-by: "Kirill A. Shutemov" > > Cc: "Kirill A. Shutemov" > > Cc: Zi Yan > > Signed-off-by: Andrew Morton > > This patch results in various boot failures (hang) on arm targets > in linux-next. Debug messages reveal the reason. > > ########### MAX_ORDER=10 start=0 __ffs(start)=-1 min()=10 min_t=-1 > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > If start==0, __ffs(start) returns 0xfffffff or (as int) -1, which min_t() > interprets as such, while min() apparently uses the returned unsigned long > value. Obviously a negative order isn't received well by the rest of the > code. Actually, __ffs() is not defined for 0. Maybe something like this? diff --git a/mm/memblock.c b/mm/memblock.c index 7911224b1ed3..63603b943bd0 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2043,7 +2043,11 @@ static void __init __free_pages_memory(unsigned long start, unsigned long end) int order; while (start < end) { - order = min_t(int, MAX_ORDER, __ffs(start)); + /* __ffs() behaviour is undefined for 0 */ + if (start) + order = min_t(int, MAX_ORDER, __ffs(start)); + else + order = MAX_ORDER; while (start + (1UL << order) > end) order--; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c8f0a8c2d049..3179c30f7958 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -605,7 +605,13 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages) * this and the first chunk to online will be pageblock_nr_pages. */ for (pfn = start_pfn; pfn < end_pfn;) { - int order = min_t(int, MAX_ORDER, __ffs(pfn)); + int order; + + /* __ffs() behaviour is undefined for 0 */ + if (pfn) + order = min_t(int, MAX_ORDER, __ffs(pfn)); + else + order = MAX_ORDER; (*online_page_callback)(pfn_to_page(pfn), order); pfn += (1UL << order); -- Kiryl Shutsemau / Kirill A. Shutemov