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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 871A9C433DF for ; Fri, 31 Jul 2020 01:15:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F458208E4 for ; Fri, 31 Jul 2020 01:15:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728262AbgGaBPR convert rfc822-to-8bit (ORCPT ); Thu, 30 Jul 2020 21:15:17 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:39684 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728080AbgGaBPR (ORCPT ); Thu, 30 Jul 2020 21:15:17 -0400 Received: from dggemi405-hub.china.huawei.com (unknown [172.30.72.56]) by Forcepoint Email with ESMTP id 6182BBEC6774B1DB2CF6; Fri, 31 Jul 2020 08:51:26 +0800 (CST) Received: from DGGEMI525-MBS.china.huawei.com ([169.254.6.120]) by dggemi405-hub.china.huawei.com ([10.3.17.143]) with mapi id 14.03.0487.000; Fri, 31 Jul 2020 08:51:24 +0800 From: "Song Bao Hua (Barry Song)" To: Mike Kravetz , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" CC: Marek Szyprowski , Michal Nazarewicz , Kyungmin Park , "Roman Gushchin" , Andrew Morton , "stable@vger.kernel.org" Subject: RE: [PATCH] cma: don't quit at first error when activating reserved areas Thread-Topic: [PATCH] cma: don't quit at first error when activating reserved areas Thread-Index: AQHWZo8CMi6/QpZbIkKrpG3q5y96kKkg21Tw Date: Fri, 31 Jul 2020 00:51:23 +0000 Message-ID: References: <20200730163123.6451-1-mike.kravetz@oracle.com> In-Reply-To: <20200730163123.6451-1-mike.kravetz@oracle.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.201.208] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org > -----Original Message----- > From: Mike Kravetz [mailto:mike.kravetz@oracle.com] > Sent: Friday, July 31, 2020 4:31 AM > To: linux-mm@kvack.org; linux-kernel@vger.kernel.org > Cc: Marek Szyprowski ; Michal Nazarewicz > ; Kyungmin Park ; > Song Bao Hua (Barry Song) ; Roman Gushchin > ; Andrew Morton ; Mike Kravetz > ; stable@vger.kernel.org > Subject: [PATCH] cma: don't quit at first error when activating reserved areas > > The routine cma_init_reserved_areas is designed to activate all reserved cma > areas. It quits when it first encounters an error. > This can leave some areas in a state where they are reserved but not activated. > There is no feedback to code which performed the reservation. Attempting to > allocate memory from areas in such a state will result in a BUG. > > Modify cma_init_reserved_areas to always attempt to activate all areas. The > called routine, cma_activate_area is responsible for leaving the area in a valid > state. No one is making active use of returned error codes, so change the > routine to void. > > How to reproduce: This example uses kernelcore, hugetlb and cma as an easy > way to reproduce. However, this is a more general cma issue. > > Two node x86 VM 16GB total, 8GB per node Kernel command line parameters, > kernelcore=4G hugetlb_cma=8G Related boot time messages, > hugetlb_cma: reserve 8192 MiB, up to 4096 MiB per node > cma: Reserved 4096 MiB at 0x0000000100000000 > hugetlb_cma: reserved 4096 MiB on node 0 > cma: Reserved 4096 MiB at 0x0000000300000000 > hugetlb_cma: reserved 4096 MiB on node 1 > cma: CMA area hugetlb could not be activated > > # echo 8 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] SMP PTI > ... > Call Trace: > bitmap_find_next_zero_area_off+0x51/0x90 > cma_alloc+0x1a5/0x310 > alloc_fresh_huge_page+0x78/0x1a0 > alloc_pool_huge_page+0x6f/0xf0 > set_max_huge_pages+0x10c/0x250 > nr_hugepages_store_common+0x92/0x120 > ? __kmalloc+0x171/0x270 > kernfs_fop_write+0xc1/0x1a0 > vfs_write+0xc7/0x1f0 > ksys_write+0x5f/0xe0 > do_syscall_64+0x4d/0x90 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Fixes: c64be2bb1c6e ("drivers: add Contiguous Memory Allocator") > Signed-off-by: Mike Kravetz > Cc: Acked-by: Barry Song > --- > mm/cma.c | 23 +++++++++-------------- > 1 file changed, 9 insertions(+), 14 deletions(-) > > diff --git a/mm/cma.c b/mm/cma.c > index 26ecff818881..0963c0f9c502 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -93,17 +93,15 @@ static void cma_clear_bitmap(struct cma *cma, > unsigned long pfn, > mutex_unlock(&cma->lock); > } > > -static int __init cma_activate_area(struct cma *cma) > +static void __init cma_activate_area(struct cma *cma) > { > unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; > unsigned i = cma->count >> pageblock_order; > struct zone *zone; > > cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL); > - if (!cma->bitmap) { > - cma->count = 0; > - return -ENOMEM; > - } > + if (!cma->bitmap) > + goto out_error; > > WARN_ON_ONCE(!pfn_valid(pfn)); > zone = page_zone(pfn_to_page(pfn)); > @@ -133,25 +131,22 @@ static int __init cma_activate_area(struct cma > *cma) > spin_lock_init(&cma->mem_head_lock); > #endif > > - return 0; > + return; > > not_in_zone: > - pr_err("CMA area %s could not be activated\n", cma->name); > bitmap_free(cma->bitmap); > +out_error: > cma->count = 0; > - return -EINVAL; > + pr_err("CMA area %s could not be activated\n", cma->name); > + return; > } > > static int __init cma_init_reserved_areas(void) { > int i; > > - for (i = 0; i < cma_area_count; i++) { > - int ret = cma_activate_area(&cma_areas[i]); > - > - if (ret) > - return ret; > - } > + for (i = 0; i < cma_area_count; i++) > + cma_activate_area(&cma_areas[i]); > > return 0; > } > -- > 2.25.4