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(p200300d82f4e3200c99da38b3f3ad4b3.dip0.t-ipconnect.de. [2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47114423862sm289821585e9.1.2025.10.21.08.44.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Oct 2025 08:44:09 -0700 (PDT) Message-ID: Date: Tue, 21 Oct 2025 17:44:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] mm/memory-failure: improve large block size folio handling. To: Zi Yan , Yang Shi Cc: linmiaohe@huawei.com, jane.chu@oracle.com, kernel@pankajraghav.com, syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, akpm@linux-foundation.org, mcgrof@kernel.org, nao.horiguchi@gmail.com, Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , "Matthew Wilcox (Oracle)" , Wei Yang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20251016033452.125479-1-ziy@nvidia.com> <20251016033452.125479-3-ziy@nvidia.com> <5EE26793-2CD4-4776-B13C-AA5984D53C04@nvidia.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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: vpv--qF9LXCfu8NObJw2gGY9zof1fyI3PV-6laNKdNI_1761061450 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 6n3xs7ed5jtm8nxq4tctw7mwud3haczw X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8DF14A0016 X-HE-Tag: 1761061456-861380 X-HE-Meta: U2FsdGVkX1/rW6S79iIdfbPuVRDGf85c5sK+NDLuMMrd2RjZnPjOzB8gf0RV0OOPrbFHLJGw4cxj7EExiv8CMfwQ7qNQKFsZQHi3r6BMC0mheKFde3C+vOTWlQ6UtYYvGl38bDlNY2L6rCb7eHUs7qOWnY+E0z+gk57Z4pDOSVR7sLNR77tqU4b1ZlnzrxANVEqztvPmnVV5UeLQCIJGtM6BEYgzcS+pK+XtlbvFqeJLDEvYWgNIqnZf3jA0yZwGqIJR/nYWyYdMPwQEiyYmoEYeFkzy2MRamxzEARLLuG8IyWW0o1U7WJyDgQII45jUwyRCbropZdlHhm6ggrg4uPGeDWpYTBF6FQkHtxQUgZudc5TIHl4RgHWu3zDT0DDfyH2ReMykOFWWy6JuiLiAcY8/zwEZWTkLoKdhbD2iMHTqHfkRof/659m4i4j9Ef/N32M6fXy0oaiXrvC2uZzx7FZtgX3RzYFHcD4oA/X+weHoCZAf5mDx2AsoikEaZgm3yBHsSTItZO7jXTqEJIdtUUS+RF5hWhr81HnVk/UoIw+gWdyOfRwSl/o+szNB9gqHF7v94PRQm0/NHvfLCE+AHoMK62JEcae7SAr67Hxvm5PcKNfR3ASqNOUYbUW0UXshIzMyfBf0Vd1cqOLVWQ3IM9zEkCE3dwFj8/PCW/oTMx4ZAZak1GtKbJVnGczgVbWheg8oRGZ9RfoHfGIZ0fXjHAeIh4i3YQhFLbY1Yh2LY/arsK/9cogsRXoF3rqtzhq5IDbdRBUjjXuDPswvauQyuvgHweORVQN+vMu7h9bVg50TtTYVhYOkeRCeEUDxM4mq3Nh6DcNDDfympxpprWcLmWXSKav6BNS++wqJzt07gibSZB4SefnMICbE2IPxjLqXzaZlSp3iY6IKpmQidlqra/ODPo3eKZHUEh3CxflEPwNsSjFv5HIf7fKBAtqtM9SJksI9fqT34pYVIdxiysk u5n8Vzmo WsiyQmV6l+Ba0f9QjwMSbJGU18Vgpp46ZECngF7pOLKnBGIMWGHxSFBklhfMM0fjAW3QF1hqwMjhby3yze/dqM9/JkmkzUcLIHagk2Igww6u1cCyizhZZy8ZQBZaau1UErAq/DfxHqT4Wkxny6Nn3ViLsz1xG3jcYDhbTNexdypirWNZfpvjdGoZQrzUzjraY8TAOAqW/EvWSxVGgmFmLktfFurZ1eBndyTurUnKa4he/yNg= 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 21.10.25 03:23, Zi Yan wrote: > On 20 Oct 2025, at 19:41, Yang Shi wrote: > >> On Mon, Oct 20, 2025 at 12:46 PM Zi Yan wrote: >>> >>> On 17 Oct 2025, at 15:11, Yang Shi wrote: >>> >>>> On Wed, Oct 15, 2025 at 8:38 PM Zi Yan wrote: >>>>> >>>>> Large block size (LBS) folios cannot be split to order-0 folios but >>>>> min_order_for_folio(). Current split fails directly, but that is not >>>>> optimal. Split the folio to min_order_for_folio(), so that, after split, >>>>> only the folio containing the poisoned page becomes unusable instead. >>>>> >>>>> For soft offline, do not split the large folio if it cannot be split to >>>>> order-0. Since the folio is still accessible from userspace and premature >>>>> split might lead to potential performance loss. >>>>> >>>>> Suggested-by: Jane Chu >>>>> Signed-off-by: Zi Yan >>>>> Reviewed-by: Luis Chamberlain >>>>> --- >>>>> mm/memory-failure.c | 25 +++++++++++++++++++++---- >>>>> 1 file changed, 21 insertions(+), 4 deletions(-) >>>>> >>>>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >>>>> index f698df156bf8..443df9581c24 100644 >>>>> --- a/mm/memory-failure.c >>>>> +++ b/mm/memory-failure.c >>>>> @@ -1656,12 +1656,13 @@ static int identify_page_state(unsigned long pfn, struct page *p, >>>>> * there is still more to do, hence the page refcount we took earlier >>>>> * is still needed. >>>>> */ >>>>> -static int try_to_split_thp_page(struct page *page, bool release) >>>>> +static int try_to_split_thp_page(struct page *page, unsigned int new_order, >>>>> + bool release) >>>>> { >>>>> int ret; >>>>> >>>>> lock_page(page); >>>>> - ret = split_huge_page(page); >>>>> + ret = split_huge_page_to_list_to_order(page, NULL, new_order); >>>>> unlock_page(page); >>>>> >>>>> if (ret && release) >>>>> @@ -2280,6 +2281,7 @@ int memory_failure(unsigned long pfn, int flags) >>>>> folio_unlock(folio); >>>>> >>>>> if (folio_test_large(folio)) { >>>>> + int new_order = min_order_for_split(folio); >>>>> /* >>>>> * The flag must be set after the refcount is bumped >>>>> * otherwise it may race with THP split. >>>>> @@ -2294,7 +2296,14 @@ int memory_failure(unsigned long pfn, int flags) >>>>> * page is a valid handlable page. >>>>> */ >>>>> folio_set_has_hwpoisoned(folio); >>>>> - if (try_to_split_thp_page(p, false) < 0) { >>>>> + /* >>>>> + * If the folio cannot be split to order-0, kill the process, >>>>> + * but split the folio anyway to minimize the amount of unusable >>>>> + * pages. >>>>> + */ >>>>> + if (try_to_split_thp_page(p, new_order, false) || new_order) { >>>> >>>> folio split will clear PG_has_hwpoisoned flag. It is ok for splitting >>>> to order-0 folios because the PG_hwpoisoned flag is set on the >>>> poisoned page. But if you split the folio to some smaller order large >>>> folios, it seems you need to keep PG_has_hwpoisoned flag on the >>>> poisoned folio. >>> >>> OK, this means all pages in a folio with folio_test_has_hwpoisoned() should be >>> checked to be able to set after-split folio's flag properly. Current folio >>> split code does not do that. I am thinking about whether that causes any >>> issue. Probably not, because: >>> >>> 1. before Patch 1 is applied, large after-split folios are already causing >>> a warning in memory_failure(). That kinda masks this issue. >>> 2. after Patch 1 is applied, no large after-split folios will appear, >>> since the split will fail. >> >> I'm a little bit confused. Didn't this patch split large folio to >> new-order-large-folio (new order is min order)? So this patch had >> code: >> if (try_to_split_thp_page(p, new_order, false) || new_order) { > > Yes, but this is Patch 2 in this series. Patch 1 is > "mm/huge_memory: do not change split_huge_page*() target order silently." > and sent separately as a hotfix[1]. I'm confused now as well. I'd like to review, will there be a v3 that only contains patch #2+#3? Thanks! -- Cheers David / dhildenb