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b=b9LRIgnew9rjfCXDGHdWBSbm4sDoGzDwTOncLSU5VTsVzU/OQXY257koPpb3fp++7 +B+yWQ+c8azWeAP8SuDqmZS8xhl+K7UdqBJb6LqXnCEelNWm98hByR39CNOxoLOcA7 DYd3xgYxQHy7PXT8ycDUxEbf/9D9q7KsKEFyh7gVhFazdad9SakRJLyK7kTLXYotUL aqEH0IRc2Z8cbZZf4DYbyrBbg7TnlXrAuQykitld2ekeBXDXHIW8AmFb989pLJvVvu YhYZPxeKAUmVW8kRnRosz93eYv2hjc6WYklu62QSWmo90FPhjLuPZep4cukFfuGH10 hqKbZeY7kvjOg== Message-ID: <72f017f2-89c5-4e4a-9ce3-ab79f70b04a0@kernel.org> Date: Wed, 5 Aug 2026 14:19:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] mm/ksm: validate KSM rmap items before hwpoison kill To: Longlong Xia , akpm@linux-foundation.org, "Lorenzo Stoakes (Arm)" Cc: xu.xin16@zte.com.cn, chengming.zhou@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia References: <20260803151151.3472893-1-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: <20260803151151.3472893-1-xialonglong2025@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 4txd7ek5e3mdddpec8utjjjkacyqwayj X-Rspamd-Queue-Id: 3E306100010 X-HE-Tag: 1785932395-41304 X-HE-Meta: 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 sdDbLF04 Bhk1SQlW8xmErOUiFlhQf7RC9AHflDLdahQjvdnAHT4SLYkvm+FbWJWDOSbEY/SW3C076RHBqP1/K2MOa2Lzb+72F7K0Zs5YfpjYzL01CPDA7iVOJQdVn72CeatshPcE1rbywSRF+gJMHAZidfGPWxYsPw6Z0xKpeur78a1Gm2jPRdopNasdYNhH4d1qYOV3p1g1jHoMvDwmcfdQUPz1GJoOUSgMPXpc7+VVzesvZ6gLoYGLvBLvVMRCkhvSoNoXjXqH5 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/3/26 17:11, Longlong Xia wrote: > From: Longlong Xia > > collect_procs_ksm() walks the stable-node rmap list and queues an > early kill for every task whose mm appears on the anon_vma chain. > > That rmap item can be stale by the time memory failure handles the > poisoned KSM page. A VMA may have been split, unmapped or remapped > after the rmap item was recorded, so matching only vma->vm_mm can send > SIGBUS with an address that no longer maps the poisoned page. > > Check that the saved address still belongs to the VMA and that > page_vma_mapped_walk() still finds the poisoned page there before > adding the task to the kill list. > > Fixes: 4248d0083ec5 ("mm: ksm: support hwpoison for ksm page") > Signed-off-by: Longlong Xia > --- > mm/ksm.c | 27 +++++++++++++++++++++++++-- > 1 file changed, 25 insertions(+), 2 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 7d5b76478f0b..bc4b2dd894d8 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -3222,6 +3222,27 @@ void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc) > } > > #ifdef CONFIG_MEMORY_FAILURE > +static bool ksm_rmap_item_mapped(const struct page *page, > + struct vm_area_struct *vma, > + unsigned long addr) Two tab indent on second parameter line 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 false; > + if (!page_vma_mapped_walk(&pvmw)) > + return false; > + page_vma_mapped_walk_done(&pvmw); > + We have page_mapped_in_vma(). So I wonder whether we can find a way to 1) Modify to just work with KSM (CCing Lorenzo) Maybe it already does. I'm confused as so often. Looking at the existing caller collect_procs_anon(), it's really only called on anon folios. Could it already be called on KSM folios? What would happen in that case? (does it just work because folio->index is still what we expect) 2) Do the following diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index d7670ba4147bf..7eeb3c336cfe9 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -342,6 +342,27 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) } #ifdef CONFIG_MEMORY_FAILURE +static unsigned long page_mapped_in_vma_at_address(const struct page *page, + struct vm_area_struct *vma, unsigned long addr) +{ + const struct folio *folio = page_folio(page); + 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); +out: + return pvmw.address; +} + /** * page_mapped_in_vma - check whether a page is really mapped in a VMA * @page: the page to test @@ -355,21 +376,10 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) unsigned long page_mapped_in_vma(const struct page *page, struct vm_area_struct *vma) { - const struct folio *folio = page_folio(page); - struct page_vma_mapped_walk pvmw = { - .pfn = page_to_pfn(page), - .nr_pages = 1, - .vma = vma, - .flags = PVMW_SYNC, - }; + const unsigned long addr = vma_address(vma, page_pgoff(folio, page), 1); - pvmw.address = vma_address(vma, page_pgoff(folio, page), 1); - if (pvmw.address == -EFAULT) - goto out; - if (!page_vma_mapped_walk(&pvmw)) + if (addr == -EFAULT) return -EFAULT; - page_vma_mapped_walk_done(&pvmw); -out: - return pvmw.address; + return page_mapped_in_vma_at_address(page, vma, addr); } #endif > + return true; > +} > + > /* > * Collect processes when the error hit an ksm page. > */ > @@ -3237,13 +3258,13 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page, > if (!stable_node) > return; > hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) { > + unsigned long addr = rmap_item->address & PAGE_MASK; Can be const. > struct anon_vma *av = rmap_item->anon_vma; > > anon_vma_lock_read(av); > rcu_read_lock(); > for_each_process(tsk) { > struct anon_vma_chain *vmac; > - unsigned long addr; > struct task_struct *t = > task_early_kill(tsk, force_early); > if (!t) > @@ -3253,7 +3274,9 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page, > { > vma = vmac->vma; > if (vma->vm_mm == t->mm) { > - addr = rmap_item->address & PAGE_MASK; > + if (!ksm_rmap_item_mapped(page, vma, > + addr)) jut put that onto a single line, please: easier to read. > + continue; > add_to_kill_ksm(t, page, vma, to_kill, > addr); > } -- Cheers, David