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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a8e38c006sm11938461f8f.46.2025.01.13.04.35.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jan 2025 04:35:59 -0800 (PST) Message-ID: Date: Mon, 13 Jan 2025 13:35:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] hwpoison, memory_hotplug: lock folio before unmap hwpoisoned folio To: Wupeng Ma , akpm@linux-foundation.org, osalvador@suse.de, nao.horiguchi@gmail.com, linmiaohe@huawei.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250113082718.1872494-1-mawupeng1@huawei.com> <20250113082718.1872494-3-mawupeng1@huawei.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250113082718.1872494-3-mawupeng1@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: WxLIN_Hp5m87UJio--lJQwUyrD-887R5-GG6G5Zjd-g_1736771761 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: F363D40013 X-Stat-Signature: a8p8euf86uhm346wdz6mxwjdyz8j5h3t X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1736771763-791504 X-HE-Meta: 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 psJ+ZNxI 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 13.01.25 09:27, Wupeng Ma wrote: > From: Ma Wupeng > > Commit b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to > be offlined) add page poison checks in do_migrate_range in order to make > offline hwpoisoned page possible by introducing isolate_lru_page and > try_to_unmap for hwpoisoned page. However folio lock must be held before > calling try_to_unmap. Add it to fix this problem. > > Waring will be produced if filio is not locked during unmap: > > ------------[ cut here ]------------ > kernel BUG at ./include/linux/swapops.h:400! > Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP > Modules linked in: > CPU: 4 UID: 0 PID: 411 Comm: bash Tainted: G W 6.13.0-rc1-00016-g3c434c7ee82a-dirty #41 > Tainted: [W]=WARN > Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 > pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : try_to_unmap_one+0xb08/0xd3c > lr : try_to_unmap_one+0x3dc/0xd3c > Call trace: > try_to_unmap_one+0xb08/0xd3c (P) > try_to_unmap_one+0x3dc/0xd3c (L) > rmap_walk_anon+0xdc/0x1f8 > rmap_walk+0x3c/0x58 > try_to_unmap+0x88/0x90 > unmap_poisoned_folio+0x30/0xa8 > do_migrate_range+0x4a0/0x568 > offline_pages+0x5a4/0x670 > memory_block_action+0x17c/0x374 > memory_subsys_offline+0x3c/0x78 > device_offline+0xa4/0xd0 > state_store+0x8c/0xf0 > dev_attr_store+0x18/0x2c > sysfs_kf_write+0x44/0x54 > kernfs_fop_write_iter+0x118/0x1a8 > vfs_write+0x3a8/0x4bc > ksys_write+0x6c/0xf8 > __arm64_sys_write+0x1c/0x28 > invoke_syscall+0x44/0x100 > el0_svc_common.constprop.0+0x40/0xe0 > do_el0_svc+0x1c/0x28 > el0_svc+0x30/0xd0 > el0t_64_sync_handler+0xc8/0xcc > el0t_64_sync+0x198/0x19c > Code: f9407be0 b5fff320 d4210000 17ffff97 (d4210000) > ---[ end trace 0000000000000000 ]--- > > Fixes: b15c87263a69 ("hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined") > Signed-off-by: Ma Wupeng > --- > mm/memory_hotplug.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 330668d37e44..9bedecfc3577 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1805,8 +1805,12 @@ static void do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) { > if (WARN_ON(folio_test_lru(folio))) > folio_isolate_lru(folio); > - if (folio_mapped(folio)) > + if (folio_mapped(folio)) { > + folio_lock(folio); > unmap_poisoned_folio(folio, TTU_IGNORE_MLOCK | TTU_HWPOISON); > + folio_unlock(folio); > + } The comment above says "have elevated reference counts", but I I wonder if this code could race with un-poisoning (although probably a rare event). If there is an elevated reference already, why not move that chunk after the folio_try_get() and just drop the comment that describes the implied magic? I mean, migration of hwpoison is dangerous either way, so that's not the biggest problem I guess :) -- Cheers, David / dhildenb