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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b778f0c866sm12128869f8f.55.2025.07.29.07.11.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Jul 2025 07:11:33 -0700 (PDT) Message-ID: <0cb3d5a5-683b-4dba-90a8-b45ab83eec53@redhat.com> Date: Tue, 29 Jul 2025 16:11:32 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/2] mm/damon: Add damos_stat support for vaddr To: Yueyang Pan , SeongJae Park , Andrew Morton , Usama Arif Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <44a30f700fdcf4470318ef5cd248ba98c59b77a2.1753794408.git.pyyjason@gmail.com> From: David Hildenbrand Content-Language: en-US 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/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: <44a30f700fdcf4470318ef5cd248ba98c59b77a2.1753794408.git.pyyjason@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29.07.25 15:53, Yueyang Pan wrote: > From: PanJason > > This patch adds support for damos_stat in virtual address space. > It leverages the walk_page_range to walk the page table and gets > the folio from page table. The last folio scanned is stored in > damos->last_applied to prevent double counting. > --- > mm/damon/vaddr.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 112 insertions(+), 1 deletion(-) > > diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c > index 87e825349bdf..3e319b51cfd4 100644 > --- a/mm/damon/vaddr.c > +++ b/mm/damon/vaddr.c > @@ -890,6 +890,117 @@ static unsigned long damos_va_migrate(struct damon_target *target, > return applied * PAGE_SIZE; > } > > +struct damos_va_stat_private { > + struct damos *scheme; > + unsigned long *sz_filter_passed; > +}; > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +static int damos_va_stat_pmd_entry(pmd_t *pmd, unsigned long addr, > + unsigned long next, struct mm_walk *walk) > +{ > + struct damos_va_stat_private *priv = walk->private; > + struct damos *s = priv->scheme; > + unsigned long *sz_filter_passed = priv->sz_filter_passed; > + struct folio *folio; > + spinlock_t *ptl; > + pmd_t pmde; > + > + ptl = pmd_lock(walk->mm, pmd); > + pmde = pmdp_get(pmd); > + > + if (!pmd_present(pmde) || !pmd_trans_huge(pmde)) > + goto unlock; > + > + /* Tell page walk code to not split the PMD */ > + walk->action = ACTION_CONTINUE; > + > + folio = damon_get_folio(pmd_pfn(pmde)); > + if (!folio) > + goto unlock; > + > + if (damon_invalid_damos_folio(folio, s)) > + goto update_last_applied; > + > + if (!damos_va_filter_out(s, folio, walk->vma, addr, NULL, pmd)){ > + *sz_filter_passed += folio_size(folio); See my comment below regarding vm_normal_page and folio references. But this split into two handlers is fairly odd. Usually we only have a pmd_entry callback (see madvise_cold_or_pageout_pte_range as an example), and handle !CONFIG_TRANSPARENT_HUGEPAGE in there. Then, there is also no need to mess with ACTION_CONTINUE > + } > + > + folio_put(folio); > +update_last_applied: > + s->last_applied = folio; > +unlock: > + spin_unlock(ptl); > + return 0; > +} > +#else > +#define damon_va_stat_pmd_entry NULL > +#endif > + > +static int damos_va_stat_pte_entry(pte_t *pte, unsigned long addr, > + unsigned long next, struct mm_walk *walk) > +{ > + struct damos_va_stat_private *priv = walk->private; > + struct damos *s = priv->scheme; > + unsigned long *sz_filter_passed = priv->sz_filter_passed; > + struct folio *folio; > + pte_t ptent; > + > + ptent = ptep_get(pte); > + if (pte_none(ptent) || !pte_present(ptent)) > + return 0; > + > + folio = damon_get_folio(pte_pfn(ptent)); > + if (!folio) > + return 0; We have vm_normal_folio() and friends for a reason -- so you don't have to do pte_pfn() manually. ... and now I am confused. We are holding the PTL, so why would you have to grab+put a folio reference here *at all*. -- Cheers, David / dhildenb