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imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lOT08OHr; spf=pass (imf02.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773221269; a=rsa-sha256; cv=none; b=mKgBI31YwuJetrrQMUu1p92q/XH41sXvKdncfRKOndTSxexifJnfzBaSaAp1Gz2LVX+KNc QrzaMZpITw8c4x6w/8LJDYaX87jSigDHfRuzGVrOQNrPO7Y1V0dcyk2tPlPiYUrPvSrbf4 JZa6uuT2WPharaTuf1piXp4Zs+3usIk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 09FE342A20; Wed, 11 Mar 2026 09:27:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35A00C4CEF7; Wed, 11 Mar 2026 09:27:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773221267; bh=38Kfamljv28cBObN05dXdaZiATQnnkS/kBzTQ5TLL1Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lOT08OHrMue36scSLTL0e9RF/OSCvZjnBMLsJurkH25A0NJP5oJ89eRBo2ThNepfb 2J0cbDmVqBBN/dTEs6CcBGbbRTNDsEadHBqzPNtd09oJSJlvUfKBR5CBfPhDBfxJyi jztDyxXqby0IfmH/WbdyGnW/DSYaIPOgu55stBcg67nqegg1bhSGLSaqkURdjQi7PK viunoEf7ue2jlwLinMG148zHSZQ3XELz68GZsb4cz/yqGRwf9Pt8EbH/mATXTpqrnv ldOsmG3xpZJ7oAZOQ0phAuT6GXtBDv57SkMCC3cQ4NL7UZh5I3kN7RngfW0MAi/99S lT55x0fi+eOtA== Message-ID: Date: Wed, 11 Mar 2026 10:27:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm: prevent droppable mappings from being locked To: Anthony Yznaga , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: akpm@linux-foundation.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jannh@google.com, pfalcato@suse.de, Jason@zx2c4.com, shuah@kernel.org References: <20260310155821.17869-1-anthony.yznaga@oracle.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: <20260310155821.17869-1-anthony.yznaga@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4DE2E80002 X-Stat-Signature: wqcg4owasz3frypk337p5qgfkjd69qx7 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773221269-983446 X-HE-Meta: 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 Ii89Hr7N iDtwDw5nb35vJax8H7y468uiqJXCVI2g0YZigdXWhq5TVn9QivjSsXXQn/rkTxr/NRUN1NGn9y3LsgQpfGE5WoG+0M/z5YKLqnbjLqMw8G7YoePphK1KiKgTo3SuF9BXouo1/zPvHtip236DY69Tgij4GJ0olz0HLmT67wbj0lrF55ItNfWOIE6B2/dtMv963MrQQlb3+73BLgY287hJAQcwkC39ix6dXQAxyT0apx0C3TrDFWac7fQwSiQwbtm8hF+DOvQzY1xrLmWE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/10/26 16:58, Anthony Yznaga wrote: > Droppable mappings must not be lockable. There is a check for VMAs with > VM_DROPPABLE set in mlock_fixup() along with checks for other types of > unlockable VMAs which ensures this when calling mlock()/mlock2(). > > For mlockall(MCL_FUTURE), the check for unlockable VMAs is different. > In apply_mlockall_flags(), if the flags parameter has MCL_FUTURE set, the > current task's mm's default VMA flag field mm->def_flags has VM_LOCKED > applied to it. VM_LOCKONFAULT is also applied if MCL_ONFAULT is also set. > When these flags are set as default in this manner they are cleared in > __mmap_complete() for new mappings that do not support mlock. A check for > VM_DROPPABLE in __mmap_complete() is missing resulting in droppable > mappings created with VM_LOCKED set. To fix this and reduce that chance of > similar bugs in the future, introduce and use vma_supports_mlock(). > > Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Should we Cc: stable? I think we should, to fix mlockall(MCL_FUTURE) behavior. > Suggested-by: David Hildenbrand > Signed-off-by: Anthony Yznaga > --- > v2: > - Implement vma_supports_mlock() instead of vma flags mask (DavidH) > - Add selftests (Lorenzo) > > include/linux/hugetlb_inline.h | 2 +- > mm/internal.h | 10 ++++++++++ > mm/mlock.c | 10 ++++++---- > mm/vma.c | 4 +--- > tools/testing/vma/include/stubs.h | 5 +++++ > 5 files changed, 23 insertions(+), 8 deletions(-) > > diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h > index 593f5d4e108b..755281fab23d 100644 > --- a/include/linux/hugetlb_inline.h > +++ b/include/linux/hugetlb_inline.h > @@ -30,7 +30,7 @@ static inline bool is_vma_hugetlb_flags(const vma_flags_t *flags) > > #endif > > -static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma) > +static inline bool is_vm_hugetlb_page(const struct vm_area_struct *vma) > { > return is_vm_hugetlb_flags(vma->vm_flags); > } > diff --git a/mm/internal.h b/mm/internal.h > index cb0af847d7d9..8c67637abcdd 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -1218,6 +1218,16 @@ static inline struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf, > } > return fpin; > } > + > +static inline bool vma_supports_mlock(const struct vm_area_struct *vma) > +{ > + if (vma->vm_flags & (VM_SPECIAL | VM_DROPPABLE)) > + return false; > + if (vma_is_dax(vma) || is_vm_hugetlb_page(vma)) > + return false; > + return vma != get_gate_vma(current->mm); As discussed, it would be great to find out whether checking get_gate_vma() makes any sense here. Likely not. :) Acked-by: David Hildenbrand (Arm) -- Cheers, David