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=1793624057; b=VYpJWcRXUB7zGOvqG792pOfYWkDwncTSyR9RDxfXxX9m5OsJavbwPVqUhmJZOCYkihrc p5vvQR10zaBBLZMEal6PKTJiQ9meRUsXKWMxH649tieqzqlbtg2M9/WYuNoGOL2kr93fF xu5Bzk/TtWTrQuemm2/eJ7/bQ0A/ZFE3zuTmy4TXqwvEo2ak/G4fIFxVv1EhrIkeM34TD FpONckx2/NFcJXkwVvFXQ3zc62Q3/aH95qMJ3s5MfgkWdEXA/uSwQshI1lBAxSTdoRNrz cDWpi66o9kZCGsa3NBlfuWeQD9ryzIhWuz2epqAVD6tFfYxGW16HL15T+mTxch82iZQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793624057; 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=MYKdbODKc1prEg/TSIAKCpPLWFj9bHZOX1ZDiVmUN/E=; b=cU+5HdMn4vk+M8njCEk1fzCiN2XDvebwJ57E9cRWDwYrTVHI4/ufb00+Ynln8VdUyneQ 7XUpXGuALUQ4USpBbO7NDWUV+w5NEpN1lMy1br6K0qOulvLqver709uBEl1X2zj4stZgQ 9T6nWkCMDj5mBNxHSzScje2a2zlGBz1CgITFqee82p2gcOQIRynLMkw0T9JIi8N/5otv9 Op7qvgAZGxNqLLz66MaN80fN/lda4nrzF7+I52gYWoA569OVPfEKMZg+gquZuEuznHv0y GvUEUfa1XtsX2CXo+HiPYz25Bw0QOIrpYW6HwwwzAdX+Gs+wWTrKyrpkZHI5RdlMVIg== 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=csvcTsOU; 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 CB61A606A326; Mon, 2 Nov 2026 12:54:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=csvcTsOU Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67B651F00A16; Mon, 2 Nov 2026 12:54:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793624056; bh=MYKdbODKc1prEg/TSIAKCpPLWFj9bHZOX1ZDiVmUN/E=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=csvcTsOUYC23IF5THZRKLkyoa8+bR3vOPOvcfHV1GbL03Pc0uq4mCw9+53mIF4ErN MtvQVl9QC1exMlpUh/LNqLsdxSLvFxPPkCNJuwA6bMm++7lghNlev2lLb67EfsqjSk 4WLj/TyIG906qxCp+7j1OM8uKsUVLiPYjJRwQMQbm5RlSiV9xdyUgX5kOTFs3SZ2VZ 8dUQakbFT6sWB0GBISiaRU2M6b9amfOtTvYlM9z1T28yTAz7Grux/KR7DRiMIoqhza 87k9tQ+6GTFFRzU4v2SQ4mtWHCViIeMReaJNBIG/DbWU10n/S+lfFR6SfaIY8HW469 ll4JZH22VNegg== Message-ID: <47abd304-e269-42dd-9d9a-3b7300ce23e3@kernel.org> Date: Mon, 2 Nov 2026 13:54:06 +0100 X-Mailing-List: linux-doc@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 02/15] mm/hugetlb: compare against persistent count when freeing lowmem folios To: Muchun Song Cc: Oscar Salvador , Naoya Horiguchi , Andrew Morton , Mel Gorman , Andy Whitcroft , Miaohe Lin , Michal Hocko , Rik van Riel , Hugh Dickins , Baolin Wang , Vivek Kasireddy , Dave Airlie , Jason Gunthorpe , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Jonathan Corbet , Shuah Khan , Randy Dunlap , Peter Xu , Breno Leitao , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Gerd Hoffmann , linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, stable@kernel.org References: <20261028-fixes_hugetlb-v1-0-a0a033db180f@kernel.org> <20261028-fixes_hugetlb-v1-2-a0a033db180f@kernel.org> <68EFA1E5-4898-4278-8718-06B1A010DFFD@linux.dev> 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: <68EFA1E5-4898-4278-8718-06B1A010DFFD@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/29/26 04:39, Muchun Song wrote: > > >> On Oct 29, 2026, at 04:13, David Hildenbrand (Arm) wrote: >> >> try_to_free_low() gets a target number of persistent folios, but >> compares it with "nr_huge_pages", which includes surplus folios. As a >> result, it can free lowmem folios below that target. >> >> For example, with two persistent folios and one surplus folio, a target >> of two can still end up freeing one persistent folio. >> >> Compare against persistent_huge_pages() instead. Convert the macro to a >> helper function and place it before try_to_free_low(). >> >> Fixes: 7893d1d505d5 ("hugetlb: Try to grow hugetlb pool for MAP_PRIVATE mappings") >> Cc: stable@kernel.org >> Signed-off-by: David Hildenbrand (Arm) > > Acked-by: Muchun Song > > One nit bellow. > >> --- >> mm/hugetlb.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index da5d04edf7c1..3a94ea1c9457 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -1335,6 +1335,11 @@ static unsigned long available_huge_pages(struct hstate *h) >> return h->free_huge_pages - h->resv_huge_pages; >> } >> >> +static unsigned long persistent_huge_pages(struct hstate *h) > > Better to make *h const? Agreed, thanks! -- Cheers, David