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(p200300cbc70ccd00c139924e359503b5.dip0.t-ipconnect.de. [2003:cb:c70c:cd00:c139:924e:3595:3b5]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43186bfcfd0sm23625305e9.26.2024.10.23.11.50.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Oct 2024 11:50:23 -0700 (PDT) Message-ID: <99d0e61b-9408-490c-8634-f44cb2487d96@redhat.com> Date: Wed, 23 Oct 2024 20:50:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: avoid VM_BUG_ON when try to map an anon large folio to zero page. To: Zi Yan , linux-mm@kvack.org, Andrew Morton Cc: usamaarif642@gmail.com, baohua@kernel.org, cerasuolodomenico@gmail.com, corbet@lwn.net, hannes@cmpxchg.org, kernel-team@meta.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, npache@redhat.com, riel@surriel.com, roman.gushchin@linux.dev, rppt@kernel.org, ryan.roberts@arm.com, ryncsn@gmail.com, shakeel.butt@linux.dev, willy@infradead.org, yuzhao@google.com References: <20241023171236.1122535-1-ziy@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 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: <20241023171236.1122535-1-ziy@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 9662A140022 X-Stat-Signature: cjzm91434sx1m4zod6gmbzhhagtfqtm9 X-Rspam-User: X-HE-Tag: 1729709415-563578 X-HE-Meta: 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 t68c5Yhj AiqQQWHZAlbCJuaDUtmd+z1r/ov17BISh/Z/+bZStqokKwcnDl+0+/zyXeguVJxsKIFf1sF6Ww7D88WcotCxUw0QesH/5fOm8nEjBaIe9xMWxkubCDh4KTh/5nu/DuSvzoj3+FVc57KuPzdt1fQebXngxq9EfB3ILNDW9XMyTtSWxwzFSaTgchqCFxbIkX4IoDcE/atdcsb2fTkPdOD2k5OkfiHqxSREeu270gMdInD2BST0YKT8alDLX6e6mFYuFMo6bZJwwa1+/u0nOIPcbKWHP/lKIkfk07oNDvCWL775sI/tTWdd30ASV0hjgqzky73mNlupdq9GyDkIEj4wT9a3nNLSxnVELuFc0lrgW0+y0B7/xIVRkmuPfjPOXLHW5Z/bHPu1KXBhok2+b7L8NsLIdLOLGpN16qRtji4YkjSXFz4lC330HuB+Kp+EdTPTCKu4Jp1D3kZf+PiBiAW5+wC40q/XzVLiJdTyoqaLDHihDoIPNJ3Z2hVLt4g== 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 23.10.24 19:12, Zi Yan wrote: > An anonymous large folio can be split into non order-0 folios, > try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but > just return false. This fixes the crash when splitting anonymous large > folios to non order-0 folios. > > Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") > Signed-off-by: Zi Yan > --- > mm/migrate.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index e950fd62607f..7ffdbe078aa7 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, > pte_t newpte; > void *addr; > > - VM_BUG_ON_PAGE(PageCompound(page), page); > + if (PageCompound(page)) > + return false; > VM_BUG_ON_PAGE(!PageAnon(page), page); > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); Would read nicer in 2024 when working on folios ;) Acked-by: David Hildenbrand -- Cheers, David / dhildenb