From patchwork Fri Feb 5 02:32:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 377621 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=unavailable 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 52ACAC433E6 for ; Fri, 5 Feb 2021 02:33:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2511A64FB6 for ; Fri, 5 Feb 2021 02:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230253AbhBECdl (ORCPT ); Thu, 4 Feb 2021 21:33:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:46018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230257AbhBECde (ORCPT ); Thu, 4 Feb 2021 21:33:34 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7CFCA64FBC; Fri, 5 Feb 2021 02:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1612492357; bh=r5DFenVBVkTL6Ifse8+fty8xgkyhRWw1Yw5CYn7AARU=; h=Date:From:To:Subject:In-Reply-To:From; b=hHmLE+q4IcpjlL33talM+L6xZoH6UlooO9EDvJNoTBD3IfaYhN/Q1DOYrZ9XvYNN5 DQuu4K6GheiPQ2iLh79PIiiSvf5IDORvEhG0MjvqTO0LQIdY3unTWLMlCA1nU5pOYI eV+h6dwdC2tim1hUE9j0D+qWDnZNbVmBK9Xd9KII= Date: Thu, 04 Feb 2021 18:32:36 -0800 From: Andrew Morton To: akpm@linux-foundation.org, bauerman@linux.ibm.com, guro@fb.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, riel@surriel.com, rppt@linux.ibm.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vvghjk1234@gmail.com Subject: [patch 10/18] memblock: do not start bottom-up allocations with kernel_end Message-ID: <20210205023236.qcEErkapb%akpm@linux-foundation.org> In-Reply-To: <20210204183135.e123f0d6027529f2cf500cf2@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Roman Gushchin Subject: memblock: do not start bottom-up allocations with kernel_end With kaslr the kernel image is placed at a random place, so starting the bottom-up allocation with the kernel_end can result in an allocation failure and a warning like this one: [ 0.002920] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node [ 0.002921] ------------[ cut here ]------------ [ 0.002922] memblock: bottom-up allocation failed, memory hotremove may be affected [ 0.002937] WARNING: CPU: 0 PID: 0 at mm/memblock.c:332 memblock_find_in_range_node+0x178/0x25a [ 0.002937] Modules linked in: [ 0.002939] CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0+ #1169 [ 0.002940] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 [ 0.002942] RIP: 0010:memblock_find_in_range_node+0x178/0x25a [ 0.002944] Code: e9 6d ff ff ff 48 85 c0 0f 85 da 00 00 00 80 3d 9b 35 df 00 00 75 15 48 c7 c7 c0 75 59 88 c6 05 8b 35 df 00 01 e8 25 8a fa ff <0f> 0b 48 c7 44 24 20 ff ff ff ff 44 89 e6 44 89 ea 48 c7 c1 70 5c [ 0.002945] RSP: 0000:ffffffff88803d18 EFLAGS: 00010086 ORIG_RAX: 0000000000000000 [ 0.002947] RAX: 0000000000000000 RBX: 0000000240000000 RCX: 00000000ffffdfff [ 0.002948] RDX: 00000000ffffdfff RSI: 00000000ffffffea RDI: 0000000000000046 [ 0.002948] RBP: 0000000100000000 R08: ffffffff88922788 R09: 0000000000009ffb [ 0.002949] R10: 00000000ffffe000 R11: 3fffffffffffffff R12: 0000000000000000 [ 0.002950] R13: 0000000000000000 R14: 0000000080000000 R15: 00000001fb42c000 [ 0.002952] FS: 0000000000000000(0000) GS:ffffffff88f71000(0000) knlGS:0000000000000000 [ 0.002953] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.002954] CR2: ffffa080fb401000 CR3: 00000001fa80a000 CR4: 00000000000406b0 [ 0.002956] Call Trace: [ 0.002961] ? memblock_alloc_range_nid+0x8d/0x11e [ 0.002963] ? cma_declare_contiguous_nid+0x2c4/0x38c [ 0.002964] ? hugetlb_cma_reserve+0xdc/0x128 [ 0.002968] ? flush_tlb_one_kernel+0xc/0x20 [ 0.002969] ? native_set_fixmap+0x82/0xd0 [ 0.002971] ? flat_get_apic_id+0x5/0x10 [ 0.002973] ? register_lapic_address+0x8e/0x97 [ 0.002975] ? setup_arch+0x8a5/0xc3f [ 0.002978] ? start_kernel+0x66/0x547 [ 0.002980] ? load_ucode_bsp+0x4c/0xcd [ 0.002982] ? secondary_startup_64_no_verify+0xb0/0xbb [ 0.002986] random: get_random_bytes called from __warn+0xab/0x110 with crng_init=0 [ 0.002988] ---[ end trace f151227d0b39be70 ]--- At the same time, the kernel image is protected with memblock_reserve(), so we can just start searching at PAGE_SIZE. In this case the bottom-up allocation has the same chances to success as a top-down allocation, so there is no reason to fallback in the case of a failure. All together it simplifies the logic. Link: https://lkml.kernel.org/r/20201217201214.3414100-2-guro@fb.com Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from low memory") Signed-off-by: Roman Gushchin Reviewed-by: Mike Rapoport Cc: Joonsoo Kim Cc: Michal Hocko Cc: Rik van Riel Cc: Wonhyuk Yang Cc: Thiago Jung Bauermann Signed-off-by: Andrew Morton --- mm/memblock.c | 49 +++++------------------------------------------- 1 file changed, 6 insertions(+), 43 deletions(-) --- a/mm/memblock.c~memblock-do-not-start-bottom-up-allocations-with-kernel_end +++ a/mm/memblock.c @@ -275,14 +275,6 @@ __memblock_find_range_top_down(phys_addr * * Find @size free area aligned to @align in the specified range and node. * - * When allocation direction is bottom-up, the @start should be greater - * than the end of the kernel image. Otherwise, it will be trimmed. The - * reason is that we want the bottom-up allocation just near the kernel - * image so it is highly likely that the allocated memory and the kernel - * will reside in the same node. - * - * If bottom-up allocation failed, will try to allocate memory top-down. - * * Return: * Found address on success, 0 on failure. */ @@ -291,8 +283,6 @@ static phys_addr_t __init_memblock membl phys_addr_t end, int nid, enum memblock_flags flags) { - phys_addr_t kernel_end, ret; - /* pump up @end */ if (end == MEMBLOCK_ALLOC_ACCESSIBLE || end == MEMBLOCK_ALLOC_KASAN) @@ -301,40 +291,13 @@ static phys_addr_t __init_memblock membl /* avoid allocating the first page */ start = max_t(phys_addr_t, start, PAGE_SIZE); end = max(start, end); - kernel_end = __pa_symbol(_end); - - /* - * try bottom-up allocation only when bottom-up mode - * is set and @end is above the kernel image. - */ - if (memblock_bottom_up() && end > kernel_end) { - phys_addr_t bottom_up_start; - - /* make sure we will allocate above the kernel */ - bottom_up_start = max(start, kernel_end); - - /* ok, try bottom-up allocation first */ - ret = __memblock_find_range_bottom_up(bottom_up_start, end, - size, align, nid, flags); - if (ret) - return ret; - - /* - * we always limit bottom-up allocation above the kernel, - * but top-down allocation doesn't have the limit, so - * retrying top-down allocation may succeed when bottom-up - * allocation failed. - * - * bottom-up allocation is expected to be fail very rarely, - * so we use WARN_ONCE() here to see the stack trace if - * fail happens. - */ - WARN_ONCE(IS_ENABLED(CONFIG_MEMORY_HOTREMOVE), - "memblock: bottom-up allocation failed, memory hotremove may be affected\n"); - } - return __memblock_find_range_top_down(start, end, size, align, nid, - flags); + if (memblock_bottom_up()) + return __memblock_find_range_bottom_up(start, end, size, align, + nid, flags); + else + return __memblock_find_range_top_down(start, end, size, align, + nid, flags); } /**