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[23.128.96.18]) by mx.google.com with ESMTP id e15si1795305ilu.146.2021.11.02.00.50.08; Tue, 02 Nov 2021 00:50:20 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=Xs8UvH0v; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=NONE dis=NONE) header.from=suse.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229770AbhKBHuD (ORCPT + 99 others); Tue, 2 Nov 2021 03:50:03 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:52730 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229505AbhKBHuC (ORCPT ); Tue, 2 Nov 2021 03:50:02 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 0830621956; Tue, 2 Nov 2021 07:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1635839247; 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=vf5M1Mpg3PLYYCAoR7F2Jy+Y+jIdkLco+jWhQ+1V2wk=; b=Xs8UvH0vLV/fN1vfUmhPvUQ9clgv+HgeQ8jrPHHf0UhIGTRji1qaNbROwkvkD3nTkBPY5t ikmCOFbLZ8Q8JzTCC9GfNcvze1bZLWl8CejAou/8A41oDtA1bxx7gVOh9wsmnTIyyB+YVD 2o+yZz+Bbiz2nYOB1nE9K26YA9PGnc8= Received: from suse.cz (unknown [10.100.201.86]) (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 CF618A3B87; Tue, 2 Nov 2021 07:47:26 +0000 (UTC) Date: Tue, 2 Nov 2021 08:47:26 +0100 From: Michal Hocko To: Alexey Makhalov Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Oscar Salvador , David Hildenbrand Subject: Re: [PATCH] mm: fix panic in __alloc_pages Message-ID: References: <20211101201312.11589-1-amakhalov@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211101201312.11589-1-amakhalov@vmware.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [CC Oscar and David] On Mon 01-11-21 13:13:12, Alexey Makhalov wrote: > There is a kernel panic caused by __alloc_pages() accessing > uninitialized NODE_DATA(nid). Uninitialized node data exists > during the time when CPU with memoryless node was added but > not onlined yet. Panic can be easy reproduced by disabling > udev rule for automatic onlining hot added CPU followed by > CPU with memoryless node hot add. > > This is a panic caused by percpu code doing allocations for > all possible CPUs and hitting this issue: > > CPU2 has been hot-added > BUG: unable to handle page fault for address: 0000000000001608 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] SMP PTI > CPU: 0 PID: 1 Comm: systemd Tainted: G E 5.15.0-rc7+ #11 > Hardware name: VMware, Inc. VMware7,1/440BX Desktop Reference Platform, BIOS VMW > > RIP: 0010:__alloc_pages+0x127/0x290 Could you resolve this into a specific line of the source code please? > Code: 4c 89 f0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 44 89 e0 48 8b 55 b8 c1 e8 0c 83 e0 01 88 45 d0 4c 89 c8 48 85 d2 0f 85 1a 01 00 00 <45> 3b 41 08 0f 82 10 01 00 00 48 89 45 c0 48 8b 00 44 89 e2 81 e2 > RSP: 0018:ffffc900006f3bc8 EFLAGS: 00010246 > RAX: 0000000000001600 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000cc2 > RBP: ffffc900006f3c18 R08: 0000000000000001 R09: 0000000000001600 > R10: ffffc900006f3a40 R11: ffff88813c9fffe8 R12: 0000000000000cc2 > R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000cc2 > FS: 00007f27ead70500(0000) GS:ffff88807ce00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000001608 CR3: 000000000582c003 CR4: 00000000001706b0 > Call Trace: > pcpu_alloc_pages.constprop.0+0xe4/0x1c0 > pcpu_populate_chunk+0x33/0xb0 > pcpu_alloc+0x4d3/0x6f0 > __alloc_percpu_gfp+0xd/0x10 > alloc_mem_cgroup_per_node_info+0x54/0xb0 > mem_cgroup_alloc+0xed/0x2f0 > mem_cgroup_css_alloc+0x33/0x2f0 > css_create+0x3a/0x1f0 > cgroup_apply_control_enable+0x12b/0x150 > cgroup_mkdir+0xdd/0x110 > kernfs_iop_mkdir+0x4f/0x80 > vfs_mkdir+0x178/0x230 > do_mkdirat+0xfd/0x120 > __x64_sys_mkdir+0x47/0x70 > ? syscall_exit_to_user_mode+0x21/0x50 > do_syscall_64+0x43/0x90 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Node can be in one of the following states: > 1. not present (nid == NUMA_NO_NODE) > 2. present, but offline (nid > NUMA_NO_NODE, node_online(nid) == 0, > NODE_DATA(nid) == NULL) > 3. present and online (nid > NUMA_NO_NODE, node_online(nid) > 0, > NODE_DATA(nid) != NULL) > > alloc_page_{bulk_array}node() functions verify for nid validity only > and do not check if nid is online. Enhanced verification check allows > to handle page allocation when node is in 2nd state. I do not think this is a correct approach. We should make sure that the proper fallback node is used instead. This means that the zone list is initialized properly. IIRC this has been a problem in the past and it has been fixed. The initialization code is quite subtle though so it is possible that this got broken again. > Signed-off-by: Alexey Makhalov > Cc: Andrew Morton > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Cc: stable@vger.kernel.org > --- > include/linux/gfp.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 55b2ec1f9..34a5a7def 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -551,7 +551,8 @@ alloc_pages_bulk_array(gfp_t gfp, unsigned long nr_pages, struct page **page_arr > static inline unsigned long > alloc_pages_bulk_array_node(gfp_t gfp, int nid, unsigned long nr_pages, struct page **page_array) > { > - if (nid == NUMA_NO_NODE) > + if (nid == NUMA_NO_NODE || (!node_online(nid) && > + !(gfp & __GFP_THISNODE))) > nid = numa_mem_id(); > > return __alloc_pages_bulk(gfp, nid, NULL, nr_pages, NULL, page_array); > @@ -578,7 +579,8 @@ __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) > static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask, > unsigned int order) > { > - if (nid == NUMA_NO_NODE) > + if (nid == NUMA_NO_NODE || (!node_online(nid) && > + !(gfp_mask & __GFP_THISNODE))) > nid = numa_mem_id(); > > return __alloc_pages_node(nid, gfp_mask, order); > -- > 2.30.0 -- Michal Hocko SUSE Labs