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b=kt+UntKS1mKD3CdD5YyzbRET6/9d98rdD+1USoOle7taqWerZrysYUDzu5d9ihTNN A8IFeBs0LRmWngc0ozxr7t5btrhKh6b+qOJ1/k8xqc6Ku9Amo2uIn1HSwO34DjyvmS slnnMdREQasqw9kzSZym8MGP5GIirQvXtAfl2RCy8inUMqzBgmy7SDdeBAqCT7o0a4 ioPuo8wIZ2anVzJUNvoT8pjRKSWdFV6DNzERhOBoFxD+qObcpuB8T4QQNnNsAjCDbx uXI6BDgooGV6+KKFzD0Xe8KtMLrWVg3uyvhvqJgryQVjMyMIIJzFBBLSS4LY7cDAku W87MDlXNktVzA== Message-ID: <1dd77152-bafa-4c4c-a85f-aba054065601@kernel.org> Date: Thu, 6 Aug 2026 10:35:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/ksm: validate KSM rmap items before hwpoison kill To: "Lorenzo Stoakes (ARM)" , Longlong Xia Cc: akpm@linux-foundation.org, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xialonglong@kylinos.cn References: <20260803151151.3472893-1-xialonglong2025@163.com> <20260805162937.1795310-1-xialonglong2025@163.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: DDD3E140004 X-Stat-Signature: 7z71537893xmeiyma466j6rpfb3gyfkt X-HE-Tag: 1786005361-778855 X-HE-Meta: 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 BTNNrnX/ vnhmseH7CorxzWyq1x33fU1T5LLp25DL6zdvRkrP5oQSYetk30dKDR8YgQG711hiTsBk0nOtVtFMvnZbRhk4rJBXv1DWjs8UiE1BILzD25QGjInsoKJnmO4D4ZDvn+eg6rx47i1S//WT28xW1Fu3s+4Pjx1UjeKxmkA8VUYA4P51aup+2frZfs48cePzkafhaPPsfijHssTutgGozPptujmxX5Q39SIfXn99ZoqTkhtwjy0G+6FUP39GvI+OLv6mZj0Ya Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> @@ -3253,9 +3253,13 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page, >> { > > OK so you're literally doing an anon rmap walk here, with the anon lock held. > >> vma = vmac->vma; >> if (vma->vm_mm == t->mm) { >> - addr = rmap_item->address & PAGE_MASK; >> + const unsigned long mapped_addr = >> + page_mapped_in_vma_at_address(page, vma, addr); > > Now you're doing another anon rmap walk? Why on earth are you doing that? And > won't this deadlock? I think it's the same as with page_mapped_in_vma(): it expects the anon vma lock to already haven been taken. At least that's what I understand when looking at collect_procs_anon. :) > > Why aren't you just checking the whether addr is contained in the range here? Yeah, that should be much easier. > > Like: > > /* Make sure VMA wasn't split/remapped */ > if (!in_range(addr, vma->vm_start, vma_pages(vma))) > continue; > > Or something? > >> + >> + if (mapped_addr == -EFAULT) >> + continue; >> add_to_kill_ksm(t, page, vma, to_kill, >> - addr); >> + mapped_addr); >> } >> } >> } >> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c >> index bac2eb5de63d..f7c5dc9248bc 100644 >> --- a/mm/page_vma_mapped.c >> +++ b/mm/page_vma_mapped.c >> @@ -336,6 +336,26 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) >> } >> >> #ifdef CONFIG_MEMORY_FAILURE >> +unsigned long page_mapped_in_vma_at_address(const struct page *page, >> + struct vm_area_struct *vma, unsigned long addr) >> +{ >> + struct page_vma_mapped_walk pvmw = { >> + .pfn = page_to_pfn(page), >> + .nr_pages = 1, >> + .vma = vma, >> + .address = addr, >> + .flags = PVMW_SYNC, >> + }; >> + >> + if (addr < vma->vm_start || addr >= vma->vm_end) >> + return -EFAULT; >> + if (!page_vma_mapped_walk(&pvmw)) >> + return -EFAULT; >> + page_vma_mapped_walk_done(&pvmw); >> + >> + return pvmw.address; >> +} > > I hate this name I hate that it's CONFIG_MEMORY_FAILURE only. Note that page_mapped_in_vma() is also KSM only. But I am curious why the function differs from what I quickly hacked together. -- Cheers, David