From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794217897; b=ceoMoVaAEH1lVDogwac3VzjRm5/V7IWvNzSTTNa5Hk/ScOb7h+How8l73i/7OMHJBwUU VuNXBcYlus9REoSeziIK6jLE9McLnI1ufXJ8RI+Tx9O653X9wg7sls/2UxVYIrD1MHRWC FAco5ERgSwI0LgHadOTM0c3IXiSMQy0iic6H/O39Cu/R9c/MKBJiBgW0YWlhLaKhTIlgP dDIl+fFUtfAVSRWHSaKceLkYg1QAIU4wduN6P74G3OBp8/s3WInXnKaJUgyp8j/zHH6rW EhGfTzL/R7/KeeN9yE9YWjdw2GCTQSfBTvYkyoK3xDgI/XSufTi46tVFCW1yd5hD7uQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794217897; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=Evsm93Jf7an7afCmpYNcizJpvuoFJEVrWxhvJjq1VG0=; b=EkapM16GPi8978B3ucLQ1OO6CjqrPForgW0MnriXy4hcyz9UM2vw+zVCOIXAw8Ah20iq 1c59wFuSLyBoz5byzB18US4yiVN/otPmLmIsp49lsN8h9fo7xtPeHeTUB4LT5NrXA51Qm E5gBq26bL/YPCaS7Id4DbjURY79D3Wfwj20m66pYYlXBUQBAelJbUB2ZoIVeNhwoXvUEZ LGD5AnBCGXNAOGPCllOY8XZAh1bAF/VzJ3Hz0thhQbzxIBtKuT3ZoTSTu76qFRWz/2pAO 13CX5Nn+VR/SPxNOcsyttpbn7+Fn+6wX5TnY3J9aeXAtak0Bg74bDrhzezSi8DbpCyw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bhqNNQOV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CDF1606A321; Mon, 9 Nov 2026 09:51:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bhqNNQOV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 398411F0089F; Mon, 9 Nov 2026 09:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794217897; bh=Evsm93Jf7an7afCmpYNcizJpvuoFJEVrWxhvJjq1VG0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bhqNNQOV9B10W1Kf+7AkY4klAiBwSyMS64uCIN5C2ry9FaHossio85/T+jcSxZFth zbBBi0sFWCFeSqS8KvSvajPokW1ehMJQfPzYOOyGXxzRPbsXl8EjF2/8ONP7xUM+XW sYwl2qRVwZseaif7xlBE9tCwEt6iL279YjBiJREbwO8R/mPiUOak4T7h/DbViQTQZg hXPJaTP8JI+Wj4hIFzuQ6JmkvfH1TEn65uzoxqrA6mEtLh5yvVX/D/he1p2v1Ocgin 1AMXAeTnbw0i2zeG1M5YIXiTSUZdO4ESqh5MnIOOwJVmtGYcCZA38e8rLX9i1b48Ub rOqb9dsZR9vMw== Message-ID: Date: Mon, 9 Nov 2026 10:51:20 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 09/47] mm/rmap: handle device-exclusive entries in folio_referenced_one() To: "Garg, Shivank" , "pratyush@kernel.org" , "osalvador@suse.de" , "xu.xin@linux.dev" , "peterx@redhat.com" , "aneesh.kumar@kernel.org" , "baoquan.he@linux.dev" , "riel@surriel.com" , "ryan.roberts@arm.com" , "mhocko@suse.com" , "usama.arif@linux.dev" , "hannes@cmpxchg.org" , "jack@suse.cz" , "pfalcato@suse.de" , "lance.yang@linux.dev" , "shakeel.butt@linux.dev" , "peterz@infradead.org" , "weixugc@google.com" , "kees@kernel.org" , "kasong@tencent.com" , "jannh@google.com" , "chrisl@kernel.org" , "liam@infradead.org" , "yuanchu@google.com" , "youngjun.park@lge.com" , "ying.huang@linux.alibaba.com" , "joshua.hahnjy@gmail.com" , "rppt@kernel.org" , "axelrasmussen@google.com" , "nphamcs@gmail.com" , "gourry@gourry.net" , "willy@infradead.org" , "baolin.wang@linux.alibaba.com" , "surenb@google.com" , "qi.zheng@linux.dev" , "matthew.brost@intel.com" , "minchan@kernel.org" , "dev.jain@arm.com" , "will@kernel.org" , "hughd@google.com" , "nico.pache@linux.dev" , "npiggin@gmail.com" , "baohua@kernel.org" , "muchun.song@linux.dev" , "harry@kernel.org" , "chengming.zhou@linux.dev" , "apopple@nvidia.com" , "ziy@nvidia.com" , "vbabka@kernel.org" , "jhubbard@nvidia.com" , "ljs@kernel.org" , "shikemeng@huaweicloud.com" , "mhocko@kernel.org" , "akpm@linux-foundation.org" , "pasha.tatashin@soleen.com" , "kas@kernel.org" , "jgg@ziepe.ca" , "rakie.kim@sk.com" Cc: "kexec@lists.infradead.org" , "linux-mm@kvack.org" , "linux-cxl@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "josef@toxicpanda.com" , "linux-fsdevel@vger.kernel.org" , "stable@vger.kernel.org" , "usama.anjum@arm.com" References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> <20261031-fixes_core-v3-9-d6437171ecc3@kernel.org> <50c50262c50da19f6a2b27f848324772b0e3c707.camel@amd.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: <50c50262c50da19f6a2b27f848324772b0e3c707.camel@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 11/9/26 06:22, Garg, Shivank wrote: > On Sat, 2026-10-31 at 10:39 +0100, David Hildenbrand (Arm) wrote: >> page_vma_mapped_walk() can return non-present device-exclusive entries, >> but folio_referenced_one() passes them to PTE young-bit accessors that >> require present PTEs. >> >> We must neither call clear_flush_young_ptes_notify() nor >> folio_pte_batch() with non-present entries. For example, clearing the >> young bit on non-present PTEs can corrupt the entry: on arm64 >> PTE_AF overlaps the swap type, so clearing it turns a device-exclusive >> entry into an ordinary swap entry. >> >> folio_pte_batch() will VM_WARN_ON_FOLIO. >> >> Apply the same approach as the previous fixes to e.g., damon_ptep_mkold(): >> treat these entries as old from the CPU's perspective and obtain their >> young state through the MMU notifier. >> >> Skip PTE batching and MGLRU look-around for non-present entries, and >> don't modify non-present PTEs. >> >> Fixes: b756a3b5e7ea ("mm: device exclusive memory access") >> Reviewed-by: Lorenzo Stoakes (ARM) >> Cc: stable@vger.kernel.org >> Reported-by: Josef Bacik >> Reviewed-by: Harry Yoo (Meta) >> Reviewed-by: Barry Song >> Reviewed-by: Dev Jain >> Tested-by: Muhammad Usama Anjum >> Signed-off-by: David Hildenbrand (Arm) >> --- >> mm/rmap.c | 23 +++++++++++++++++++---- >> 1 file changed, 19 insertions(+), 4 deletions(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 1131b76bbbc28..0faef46806e5c 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -924,6 +924,7 @@ static bool folio_referenced_one(struct folio *folio, >> DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); >> int ptes = 0, referenced = 0; >> unsigned int nr; >> + pte_t pteval; >> >> while (page_vma_mapped_walk(&pvmw)) { >> address = pvmw.address; >> @@ -968,10 +969,12 @@ static bool folio_referenced_one(struct folio *folio, >> return false; >> } >> >> - if (pvmw.pte && folio_test_large(folio)) { >> + if (pvmw.pte) >> + pteval = ptep_get(pvmw.pte); >> + >> + if (pvmw.pte && pte_present(pteval) && folio_test_large(folio)) { >> const unsigned long end_addr = pmd_addr_end(address, vma->vm_end); >> const unsigned int max_nr = (end_addr - address) >> PAGE_SHIFT; >> - pte_t pteval = ptep_get(pvmw.pte); >> >> nr = folio_pte_batch(folio, pvmw.pte, pteval, max_nr); >> } >> @@ -981,11 +984,23 @@ static bool folio_referenced_one(struct folio *folio, >> * are. —they could be on active/inactive lists or on MGLRU. So the >> * simplest approach is to disable this look-around optimization. >> */ >> - if (lru_gen_enabled() && !lru_gen_switching() && pvmw.pte) { >> + if (lru_gen_enabled() && !lru_gen_switching() && pvmw.pte && >> + pte_present(pteval)) { >> if (lru_gen_look_around(&pvmw, nr)) >> referenced++; >> } else if (pvmw.pte) { >> - if (clear_flush_young_ptes_notify(vma, address, pvmw.pte, nr)) > > This was the only caller of clear_flush_young_ptes_notify(), so this > leaves both definitions in mm/internal.h unused. > > Would you prefer to remove them, or keep them for company with their > still used test_and_clear_young_ptes_notify friend? Can you send a cleanup? Thanks! -- Cheers, David