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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 34AE2C4360F for ; Wed, 3 Apr 2019 09:31:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F27522082C for ; Wed, 3 Apr 2019 09:31:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726584AbfDCJbF (ORCPT ); Wed, 3 Apr 2019 05:31:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35266 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725940AbfDCJbE (ORCPT ); Wed, 3 Apr 2019 05:31:04 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 628B581F19; Wed, 3 Apr 2019 09:31:03 +0000 (UTC) Received: from [10.36.117.246] (ovpn-117-246.ams2.redhat.com [10.36.117.246]) by smtp.corp.redhat.com (Postfix) with ESMTP id DC8FA19724; Wed, 3 Apr 2019 09:30:59 +0000 (UTC) Subject: Re: [PATCH 4/6] mm/hotplug: Reorder arch_remove_memory() call in __remove_memory() To: Anshuman Khandual , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, akpm@linux-foundation.org, will.deacon@arm.com, catalin.marinas@arm.com Cc: mhocko@suse.com, mgorman@techsingularity.net, james.morse@arm.com, mark.rutland@arm.com, robin.murphy@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, osalvador@suse.de, logang@deltatee.com, pasha.tatashin@oracle.com, cai@lca.pw References: <1554265806-11501-1-git-send-email-anshuman.khandual@arm.com> <1554265806-11501-5-git-send-email-anshuman.khandual@arm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <1554265806-11501-5-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 03 Apr 2019 09:31:03 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.04.19 06:30, Anshuman Khandual wrote: > Memory hot remove uses get_nid_for_pfn() while tearing down linked sysfs > entries between memory block and node. It first checks pfn validity with > pfn_valid_within() before fetching nid. With CONFIG_HOLES_IN_ZONE config > (arm64 has this enabled) pfn_valid_within() calls pfn_valid(). > > pfn_valid() is an arch implementation on arm64 (CONFIG_HAVE_ARCH_PFN_VALID) > which scans all mapped memblock regions with memblock_is_map_memory(). This > creates a problem in memory hot remove path which has already removed given > memory range from memory block with memblock_[remove|free] before arriving > at unregister_mem_sect_under_nodes(). Hence get_nid_for_pfn() returns -1 > skipping subsequent sysfs_remove_link() calls leaving node <-> memory block > sysfs entries as is. Subsequent memory add operation hits BUG_ON() because > of existing sysfs entries. > > [ 62.007176] NUMA: Unknown node for memory at 0x680000000, assuming node 0 > [ 62.052517] ------------[ cut here ]------------ > [ 62.053211] kernel BUG at mm/memory_hotplug.c:1143! > [ 62.053868] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP > [ 62.054589] Modules linked in: > [ 62.054999] CPU: 19 PID: 3275 Comm: bash Not tainted 5.1.0-rc2-00004-g28cea40b2683 #41 > [ 62.056274] Hardware name: linux,dummy-virt (DT) > [ 62.057166] pstate: 40400005 (nZcv daif +PAN -UAO) > [ 62.058083] pc : add_memory_resource+0x1cc/0x1d8 > [ 62.058961] lr : add_memory_resource+0x10c/0x1d8 > [ 62.059842] sp : ffff0000168b3ce0 > [ 62.060477] x29: ffff0000168b3ce0 x28: ffff8005db546c00 > [ 62.061501] x27: 0000000000000000 x26: 0000000000000000 > [ 62.062509] x25: ffff0000111ef000 x24: ffff0000111ef5d0 > [ 62.063520] x23: 0000000000000000 x22: 00000006bfffffff > [ 62.064540] x21: 00000000ffffffef x20: 00000000006c0000 > [ 62.065558] x19: 0000000000680000 x18: 0000000000000024 > [ 62.066566] x17: 0000000000000000 x16: 0000000000000000 > [ 62.067579] x15: ffffffffffffffff x14: ffff8005e412e890 > [ 62.068588] x13: ffff8005d6b105d8 x12: 0000000000000000 > [ 62.069610] x11: ffff8005d6b10490 x10: 0000000000000040 > [ 62.070615] x9 : ffff8005e412e898 x8 : ffff8005e412e890 > [ 62.071631] x7 : ffff8005d6b105d8 x6 : ffff8005db546c00 > [ 62.072640] x5 : 0000000000000001 x4 : 0000000000000002 > [ 62.073654] x3 : ffff8005d7049480 x2 : 0000000000000002 > [ 62.074666] x1 : 0000000000000003 x0 : 00000000ffffffef > [ 62.075685] Process bash (pid: 3275, stack limit = 0x00000000d754280f) > [ 62.076930] Call trace: > [ 62.077411] add_memory_resource+0x1cc/0x1d8 > [ 62.078227] __add_memory+0x70/0xa8 > [ 62.078901] probe_store+0xa4/0xc8 > [ 62.079561] dev_attr_store+0x18/0x28 > [ 62.080270] sysfs_kf_write+0x40/0x58 > [ 62.080992] kernfs_fop_write+0xcc/0x1d8 > [ 62.081744] __vfs_write+0x18/0x40 > [ 62.082400] vfs_write+0xa4/0x1b0 > [ 62.083037] ksys_write+0x5c/0xc0 > [ 62.083681] __arm64_sys_write+0x18/0x20 > [ 62.084432] el0_svc_handler+0x88/0x100 > [ 62.085177] el0_svc+0x8/0xc > > Re-ordering arch_remove_memory() with memblock_[free|remove] solves the > problem on arm64 as pfn_valid() behaves correctly and returns positive > as memblock for the address range still exists. arch_remove_memory() > removes applicable memory sections from zone with __remove_pages() and > tears down kernel linear mapping. Removing memblock regions afterwards > is consistent. > > Signed-off-by: Anshuman Khandual > --- > mm/memory_hotplug.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 0082d69..71d0d79 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1872,11 +1872,10 @@ void __ref __remove_memory(int nid, u64 start, u64 size) > > /* remove memmap entry */ > firmware_map_remove(start, start + size, "System RAM"); > + arch_remove_memory(nid, start, size, NULL); > memblock_free(start, size); > memblock_remove(start, size); > > - arch_remove_memory(nid, start, size, NULL); > - > try_offline_node(nid); > > mem_hotplug_done(); > As discussed, with tweaked wording Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb