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 D07BC3ACA46 for ; Wed, 16 Sep 2026 06:12:25 +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=1789539147; cv=none; b=p5K0+mB8x2Co2ydRxOLoYNWrw7oPjXOQnCiQMeJMk0pN4cd28L7aE8/CRpWcWCba1L6i1StlyuA/bANSsgEuIuHdAJMHI639VZsOp3Xg576TEs6s4c8j+7d9ECgbSuK7vWt8hvrqWrDPRXwQE3c5gwunzI0N8uTxj+9IqYMuU4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789539147; c=relaxed/simple; bh=QQfdtee+0fj/mxrJpRwYUPi85x36SFeorWl1kY9jW98=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tWRk+mpTMFjDe86wCk+wO9KmYZ8mewQbp15lmx5x5BDTdiF6Gpm6yaSw7rgFY2eN2K3MhqdavqQfMjEkWyV5yu2MRQuT+3/0QsLUrWb1T2XkLdO9wsE4/v2mL3f52prlWQp/sIhr6BhxK1LGrLKv6DqYZF+lR1Ji0ocQ+aggFyQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GW2zjHlD; 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="GW2zjHlD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8C831F000FF; Wed, 16 Sep 2026 06:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789539145; bh=X6Pgd9VK8mpSZf4/s8Zo2FUO4nqPRKKV5sJgzNVBD/M=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GW2zjHlD5N61EWUI3NmTflCzPGuJkyU+QXmd1DP/4DgIkjqxgqZ4sCR/5QEY7yYJq rNjrCiGXWYyMwg9/CPji+rkUKcj+x24AzZnnm5tCTC3qAAL9D0E6hlfcJaxkGRd4X9 0UH3/soKBy1M/oeP34Qd1GpXlEd5jqJKBwNYVHJ1lbpdEtHm+OidS3tEZ0CtclVGOG amlInPBB3YWEb1dYe3KRTDxfjSvfqvHdoKcO+3ssKawblK2dziIJP52+HKLnRr8NWd YfZJ9rCXJUWeOLuBHZghMUPnpLEpWzIjayA6aIjibgibDm4JwKeNOjWxGqph16JfoW 7mCy2kMRKOfzA== Message-ID: Date: Wed, 16 Sep 2026 08:12:18 +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 05/16] mm/hugetlb: use direct assignment instead of folio_change_private() To: Zi Yan , "Matthew Wilcox (Oracle)" , Andrew Morton , Muchun Song , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Gregory Price , Ying Huang , Alistair Popple , Johannes Weiner , Qi Zheng , Shakeel Butt , Kairui Song Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador References: <20260913-remove-pg_private-v4-0-848550f7574e@nvidia.com> <20260913-remove-pg_private-v4-5-848550f7574e@nvidia.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/16/26 03:56, Zi Yan wrote: > On 13 Sep 2026, at 22:24, Zi Yan wrote: > >> folio_change_private() should be used along with folio_attach_private() and >> folio_detach_private(), where adding and remove ->private content requires >> folio refcount change. add_hugetlb_folio() simply sets folio->private to >> NULL without refcount manipulation. Change it to direct assignment to avoid >> semantic confusion. >> >> It prepares for a future commit that remove PG_private. >> >> No functional change intended. >> >> Assisted-by: LLM >> To: Muchun Song >> To: Oscar Salvador >> To: Andrew Morton >> Cc: David Hildenbrand >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org >> Acked-by: Usama Arif >> Reviewed-by: Gregory Price (Meta) >> Signed-off-by: Zi Yan >> --- >> mm/hugetlb.c | 7 ++----- >> 1 file changed, 2 insertions(+), 5 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index d3a0650ff6905..8d551cdaef9db 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -1446,11 +1446,8 @@ void add_hugetlb_folio(struct hstate *h, struct folio *folio, >> } >> >> __folio_set_hugetlb(folio); >> - folio_change_private(folio, NULL); >> - /* >> - * We have to set hugetlb_vmemmap_optimized again as above >> - * folio_change_private(folio, NULL) cleared it. >> - */ >> + /* Clear all folio->private flags except hugetlb_vmemmap_optimized. */ >> + folio->private = NULL; >> folio_set_hugetlb_vmemmap_optimized(folio); >> > > Sashiko[1] said when a CMA hugetlb folio is freed but fails vmemmap restore, > add_hugetlb_folio() clears HPG_cma. It either bypasses > hugetlb_cma_free_frozen_folio() due to the missing HPG_cma flag, or > skips cma_release() and causes a CMA memory leak if it is free directly > to buddy allocator. Sashiko also asked if HPG_temporary should be preserved > as well HPG_cma. > > Answer: > > Missing HPG_cma is a real issue. It can be fixed by checking > folio_test_hugetlb_cma(folio) at the beginning of add_hugetlb_folio() and > setting HPG_cma after folio->private is assigned to NULL. Maybe we should just simply only clear flags we actually want to clear ... -- Cheers, David