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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B07B4C6FD18 for ; Tue, 18 Apr 2023 23:33:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230027AbjDRXdZ (ORCPT ); Tue, 18 Apr 2023 19:33:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229879AbjDRXdY (ORCPT ); Tue, 18 Apr 2023 19:33:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90211E7 for ; Tue, 18 Apr 2023 16:33:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2E9FD62BAD for ; Tue, 18 Apr 2023 23:33:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AC7EC433D2; Tue, 18 Apr 2023 23:33:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1681860802; bh=Z4kiETUHPihuMkPMPI0yH6GApjQyxdRlstZGcOK81f8=; h=Date:To:From:Subject:From; b=PWx2hILhGnto3Y1gNstHRGZaVvJ+6FrGlG6LY+SMmQycoW5prFzcS4x/omQPMd0jN I+wH+eZ24QpYNhP8E0pzjbwi3fR1BUcr/GzEAk8F9oMMJyJNikWf3OUKl2Rgh3oZJY ukY87i4Y7HuDOM+EaeDDib32AM+6Y+EonXsFdtjo= Date: Tue, 18 Apr 2023 16:33:21 -0700 To: mm-commits@vger.kernel.org, rppt@kernel.org, linux@roeck-us.net, kirill@shutemov.name, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-treewide-redefine-max_order-sanely-fix-fix.patch removed from -mm tree Message-Id: <20230418233322.7AC7EC433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: avoid passing 0 to __ffs() has been removed from the -mm tree. Its filename was mm-treewide-redefine-max_order-sanely-fix-fix.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "Kirill A. Shutemov" Subject: mm: avoid passing 0 to __ffs() Date: Thu, 6 Apr 2023 10:25:29 +0300 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") results in various boot failures (hang) on arm targets 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. [akpm@linux-foundation.org: fix comment, per Mike] Link: https://lkml.kernel.org/r/ZDBa7HWZK69dKKzH@kernel.org Link: https://lkml.kernel.org/r/20230406072529.vupqyrzqnhyozeyh@box.shutemov.name Fixes: 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") Signed-off-by: "Kirill A. Shutemov" Reported-by: Guenter Roeck Link: https://lkml.kernel.org/r/9460377a-38aa-4f39-ad57-fb73725f92db@roeck-us.net Reviewed-by: Mike Rapoport (IBM) Signed-off-by: Andrew Morton --- mm/memblock.c | 11 ++++++++++- mm/memory_hotplug.c | 13 ++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) --- a/mm/memblock.c~mm-treewide-redefine-max_order-sanely-fix-fix +++ a/mm/memblock.c @@ -2043,7 +2043,16 @@ static void __init __free_pages_memory(u int order; while (start < end) { - order = min_t(int, MAX_ORDER, __ffs(start)); + /* + * Free the pages in the largest chunks alignment allows. + * + * __ffs() behaviour is undefined for 0. start == 0 is + * MAX_ORDER-aligned, set order to MAX_ORDER for the case. + */ + if (start) + order = min_t(int, MAX_ORDER, __ffs(start)); + else + order = MAX_ORDER; while (start + (1UL << order) > end) order--; --- a/mm/memory_hotplug.c~mm-treewide-redefine-max_order-sanely-fix-fix +++ a/mm/memory_hotplug.c @@ -605,7 +605,18 @@ static void online_pages_range(unsigned * 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; + + /* + * Free to online pages in the largest chunks alignment allows. + * + * __ffs() behaviour is undefined for 0. start == 0 is + * MAX_ORDER-aligned, Set order to MAX_ORDER for the case. + */ + 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); _ Patches currently in -mm which might be from kirill@shutemov.name are