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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a532463e11sm11568362f8f.90.2025.06.10.00.04.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Jun 2025 00:04:19 -0700 (PDT) Message-ID: <65c1df74-4e58-4a09-9451-b18dae5adb3f@redhat.com> Date: Tue, 10 Jun 2025 09:04:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC] mm: madvise: use per_vma lock for MADV_FREE To: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Barry Song , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Suren Baghdasaryan , Lokesh Gidra , Mike Rapoport , Michal Hocko , Tangquan Zheng , Qi Zheng References: <20250610055920.21323-1-21cnbao@gmail.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: <20250610055920.21323-1-21cnbao@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: h2_oEahbKIuEAsYKvfca-TvE0ZquGncJ3BvOXQ-hJ1E_1749539061 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: D109110000F X-Stat-Signature: 6pcmjsfjb8yhym78z1z1ui5ajbs3y34n X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1749539063-940008 X-HE-Meta: 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 jFMX6Cag 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 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 10.06.25 07:59, Barry Song wrote: > From: Barry Song > > MADV_FREE is another option, besides MADV_DONTNEED, for dynamic memory > freeing in user-space native or Java heap memory management. For example, > jemalloc can be configured to use MADV_FREE, and recent versions of the > Android Java heap have also increasingly adopted MADV_FREE. Supporting > per-VMA locking for MADV_FREE thus appears increasingly necessary. > > We have replaced walk_page_range() with walk_page_range_vma(). Along with > the proposed madvise_lock_mode by Lorenzo, the necessary infrastructure is > now in place to begin exploring per-VMA locking support for MADV_FREE and > potentially other madvise using walk_page_range_vma(). > > This patch adds support for the PGWALK_VMA_RDLOCK walk_lock mode in > walk_page_range_vma(), and leverages madvise_lock_mode from > madv_behavior to select the appropriate walk_lock—either mmap_lock or > per-VMA lock—based on the context. > > To ensure thread safety, madvise_free_walk_ops is now defined as a stack > variable instead of a global constant. > > Cc: Lorenzo Stoakes > Cc: "Liam R. Howlett" > Cc: David Hildenbrand > Cc: Vlastimil Babka > Cc: Jann Horn > Cc: Suren Baghdasaryan > Cc: Lokesh Gidra > Cc: Mike Rapoport > Cc: Michal Hocko > Cc: Tangquan Zheng > Cc: Qi Zheng > Signed-off-by: Barry Song > --- > include/linux/pagewalk.h | 2 ++ > mm/madvise.c | 20 ++++++++++++++------ > mm/pagewalk.c | 6 ++++++ > 3 files changed, 22 insertions(+), 6 deletions(-) > > diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h > index 9700a29f8afb..a4afa64ef0ab 100644 > --- a/include/linux/pagewalk.h > +++ b/include/linux/pagewalk.h > @@ -14,6 +14,8 @@ enum page_walk_lock { > PGWALK_WRLOCK = 1, > /* vma is expected to be already write-locked during the walk */ > PGWALK_WRLOCK_VERIFY = 2, > + /* vma is expected to be already read-locked during the walk */ > + PGWALK_VMA_RDLOCK_VERIFY = 3, > }; > > /** > diff --git a/mm/madvise.c b/mm/madvise.c > index 381eedde8f6d..23d58eb31c8f 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -775,10 +775,14 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, > return 0; > } > > -static const struct mm_walk_ops madvise_free_walk_ops = { > - .pmd_entry = madvise_free_pte_range, > - .walk_lock = PGWALK_RDLOCK, > -}; > +static inline enum page_walk_lock get_walk_lock(enum madvise_lock_mode mode) > +{ > + /* Other modes don't require fixing up the walk_lock. */ > + VM_WARN_ON_ONCE(mode != MADVISE_VMA_READ_LOCK && > + mode != MADVISE_MMAP_READ_LOCK); > + return mode == MADVISE_VMA_READ_LOCK ? > + PGWALK_VMA_RDLOCK_VERIFY : PGWALK_RDLOCK; > +} > > static int madvise_free_single_vma(struct madvise_behavior *madv_behavior, > struct vm_area_struct *vma, > @@ -787,6 +791,9 @@ static int madvise_free_single_vma(struct madvise_behavior *madv_behavior, > struct mm_struct *mm = vma->vm_mm; > struct mmu_notifier_range range; > struct mmu_gather *tlb = madv_behavior->tlb; > + struct mm_walk_ops walk_ops = { > + .pmd_entry = madvise_free_pte_range, > + }; > > /* MADV_FREE works for only anon vma at the moment */ > if (!vma_is_anonymous(vma)) > @@ -806,8 +813,9 @@ static int madvise_free_single_vma(struct madvise_behavior *madv_behavior, > > mmu_notifier_invalidate_range_start(&range); > tlb_start_vma(tlb, vma); > + walk_ops.walk_lock = get_walk_lock(madv_behavior->lock_mode); > walk_page_range_vma(vma, range.start, range.end, > - &madvise_free_walk_ops, tlb); > + &walk_ops, tlb); > tlb_end_vma(tlb, vma); > mmu_notifier_invalidate_range_end(&range); > return 0; > @@ -1653,7 +1661,6 @@ static enum madvise_lock_mode get_lock_mode(struct madvise_behavior *madv_behavi > case MADV_WILLNEED: > case MADV_COLD: > case MADV_PAGEOUT: > - case MADV_FREE: > case MADV_POPULATE_READ: > case MADV_POPULATE_WRITE: > case MADV_COLLAPSE: > @@ -1662,6 +1669,7 @@ static enum madvise_lock_mode get_lock_mode(struct madvise_behavior *madv_behavi > return MADVISE_MMAP_READ_LOCK; > case MADV_DONTNEED: > case MADV_DONTNEED_LOCKED: > + case MADV_FREE: > return MADVISE_VMA_READ_LOCK; > default: > return MADVISE_MMAP_WRITE_LOCK; > diff --git a/mm/pagewalk.c b/mm/pagewalk.c > index e478777c86e1..c984aacc5552 100644 > --- a/mm/pagewalk.c > +++ b/mm/pagewalk.c > @@ -420,6 +420,9 @@ static int __walk_page_range(unsigned long start, unsigned long end, > static inline void process_mm_walk_lock(struct mm_struct *mm, > enum page_walk_lock walk_lock) > { > + if (walk_lock == PGWALK_VMA_RDLOCK_VERIFY) > + return; > + > if (walk_lock == PGWALK_RDLOCK) > mmap_assert_locked(mm); Nit: I'd have converted the "else" into "else if (walk_lock != PGWALK_VMA_RDLOCK_VERIFY) > else > @@ -437,6 +440,9 @@ static inline void process_vma_walk_lock(struct vm_area_struct *vma, > case PGWALK_WRLOCK_VERIFY: > vma_assert_write_locked(vma); > break; > + case PGWALK_VMA_RDLOCK_VERIFY: > + vma_assert_locked(vma); > + break; > case PGWALK_RDLOCK: > /* PGWALK_RDLOCK is handled by process_mm_walk_lock */ > break; Nothing jumped at me an I think this should be ok Acked-by: David Hildenbrand -- Cheers, David / dhildenb