From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 556643EFD3B for ; Wed, 17 Jun 2026 12:28:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781699330; cv=none; b=PruPc9ccpgpwxoA0JLyV5X6nUvdWjFPo6liOiE9+bm+Sm7eGiz1BjTGbA0r1nFbkHEn2gWsLne6TknTplnCQCOp1RD+Tl7+2lKwZ4kA8KnMnVn8pzTUZC+EjfD54+6ll57pINS2npNtQu02tAZzXt2y/JIgm3q2UaYA3txTp8NM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781699330; c=relaxed/simple; bh=3pVgUbo2U8TOT4s9C4i1k9xjvie9IfyA5FVmCWEo4lk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=e1zYSAc72UyoHNmeCN8WghnpfGdoRg+T5GU3g78+hsFTqAsA6xaBT+5azcnR8cAWKSKPytVPX4RmdjdZZ2YvApaf4FFgXfnWYEfY6dDo1LseVCx4qQvbVLZsO5KQ/Us76KPonDbY/ot09o2PRL/CAFUtWCvCnMfnJFCGPSt4BjM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aPu0lwpL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aPu0lwpL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D6881F000E9; Wed, 17 Jun 2026 12:28:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781699327; bh=mLeD86WlaOzT6NMJq1mWVXP+jO3RbCBQR26svGNQO/Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=aPu0lwpLerB36iAslE6t72DuGoUvNHsGDCoXJHzSwA4YW/NjJyaDt+rl84MRMFnul 7/WkoIyvV5Edo1017A9I6dxi5XZkKhjLiFeZU67o3pCgjevg3TndZO88HQdMXJsYSd HNjWKm2M/aQX1iAj9MEUo3UIhs44NXDNk51fDK+r8iK6dZn2I3ZjiC4ugHaMH50FZd vojPOYSoL2fULeUgBoqx7STZzdG3MMZOXE2LCDKA/pfqCOCvLvJtq9ncw15r9dlAwr UuOoK0qsRQuu6CCNznHS3y6VMCFaDHC2exTr0U8klHJvN6f5t7ZR4G7P2eQWCTLI+E HsVTLOARVFQKQ== Message-ID: <72874bf7-d2f7-4bb9-9211-804533bd5c19@kernel.org> Date: Wed, 17 Jun 2026 14:28:42 +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 v4 4/5] mm/vmscan: extract folio unmap logic into folio_try_unmap() To: Zhang Peng , Andrew Morton , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Michal Hocko , "Liam R. Howlett" , Qi Zheng Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song , Kairui Song , Zhang Peng References: <20260525-batch-tlb-flush-v4-0-83789d6abc00@icloud.com> <20260525-batch-tlb-flush-v4-4-83789d6abc00@icloud.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: <20260525-batch-tlb-flush-v4-4-83789d6abc00@icloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/25/26 16:57, Zhang Peng wrote: > shrink_folio_list() contains a self-contained block that sets up > TTU flags and calls try_to_unmap(), accounting for failures via > reclaim_stat. Extract it into folio_try_unmap() to reduce the size > of shrink_folio_list() and make the unmap step independently readable. > > folio_try_unmap() is only called when the folio is actually mapped; > the !folio_mapped() check stays in the caller, keeping the function's > semantics clear: it tries to unmap a mapped folio and returns whether > the unmap succeeded. > > No functional change. > > Signed-off-by: Zhang Peng > --- > mm/vmscan.c | 68 ++++++++++++++++++++++++++++++++++--------------------------- > 1 file changed, 38 insertions(+), 30 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 456d38eb172c..abf3a2878456 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1221,6 +1221,41 @@ static bool pageout_one(struct folio *folio, > return false; > } > > +static bool folio_try_unmap(struct folio *folio, struct reclaim_stat *stat, > + unsigned int nr_pages) Two tabs. folio_try_unmap() vs. try_to_unmap() Hm. Again, maybe we should throw in a "for_reclaim" ? folio_try_unmap_for_reclaim() ? Not sure. > +{ > + enum ttu_flags flags = TTU_BATCH_FLUSH; > + bool was_swapbacked; > + > + was_swapbacked = folio_test_swapbacked(folio); const bool was_swapbacked = folio_test_swapbacked(folio); > + if (folio_test_pmd_mappable(folio)) > + flags |= TTU_SPLIT_HUGE_PMD; > + /* > + * Without TTU_SYNC, try_to_unmap will only begin to > + * hold PTL from the first present PTE within a large > + * folio. Some initial PTEs might be skipped due to > + * races with parallel PTE writes in which PTEs can be > + * cleared temporarily before being written new present > + * values. This will lead to a large folio is still > + * mapped while some subpages have been partially > + * unmapped after try_to_unmap; TTU_SYNC helps > + * try_to_unmap acquire PTL from the first PTE, > + * eliminating the influence of temporary PTE values. > + */ Comment can now use less LOC. > + if (folio_test_large(folio)) > + flags |= TTU_SYNC; > + > + try_to_unmap(folio, flags); > + if (folio_mapped(folio)) { > + stat->nr_unmap_fail += nr_pages; > + if (!was_swapbacked && > + folio_test_swapbacked(folio)) Probably best in a single line. > + stat->nr_lazyfree_fail += nr_pages; > + return false; > + } > + return true; > +} > + > /* > * Reclaimed folios are counted in the return value. > */ > @@ -1495,36 +1530,9 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, > * The folio is mapped into the page tables of one or more > * processes. Try to unmap it here. > */ > - if (folio_mapped(folio)) { > - enum ttu_flags flags = TTU_BATCH_FLUSH; > - bool was_swapbacked = folio_test_swapbacked(folio); > - > - if (folio_test_pmd_mappable(folio)) > - flags |= TTU_SPLIT_HUGE_PMD; > - /* > - * Without TTU_SYNC, try_to_unmap will only begin to > - * hold PTL from the first present PTE within a large > - * folio. Some initial PTEs might be skipped due to > - * races with parallel PTE writes in which PTEs can be > - * cleared temporarily before being written new present > - * values. This will lead to a large folio is still > - * mapped while some subpages have been partially > - * unmapped after try_to_unmap; TTU_SYNC helps > - * try_to_unmap acquire PTL from the first PTE, > - * eliminating the influence of temporary PTE values. > - */ > - if (folio_test_large(folio)) > - flags |= TTU_SYNC; > - > - try_to_unmap(folio, flags); > - if (folio_mapped(folio)) { > - stat->nr_unmap_fail += nr_pages; > - if (!was_swapbacked && > - folio_test_swapbacked(folio)) > - stat->nr_lazyfree_fail += nr_pages; > - goto activate_locked; > - } > - } > + if (folio_mapped(folio) && > + !folio_try_unmap(folio, stat, nr_pages)) Probably best in a single line. > + goto activate_locked; > > /* > * Folio is unmapped now so it cannot be newly pinned anymore. > -- Cheers, David