From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BD686C61DC4 for ; Thu, 27 Aug 2026 16:00:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B0CDE6B0098; Thu, 27 Aug 2026 12:00:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE4AC6B0099; Thu, 27 Aug 2026 12:00:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9FAB06B009B; Thu, 27 Aug 2026 12:00:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 772B46B0098 for ; Thu, 27 Aug 2026 12:00:44 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 0D439C0485 for ; Thu, 27 Aug 2026 16:00:44 +0000 (UTC) X-FDA: 85147512408.27.335AA00 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id 1DFE3180009 for ; Thu, 27 Aug 2026 16:00:41 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=V6PLoF46; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787846442; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nrlTIkFE6/b+AXgWzKleN3cfwGZ9PDfL2MFZp1jZv4Q=; b=cMU1D5p2QznX7Kjq8CQ9H3F+nuCmnJ32MR+nLhmZd76VJcdZzU8AlO3TJIyflEsbhA9jzu LQqGHtvg3XFrsOQ0D3P9siLEFDTL8UoR+sRU8ARuOt784eHZ709CXvg9+PSXkRCDKsSs6T nXXXjUJu6Dey2s/TvBT1DgM7s++qQiQ= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787846442; b=jNELQwvJXs99AVKoyNpg/4nmhyWrovQEnxDP+pSOujJgXqEV//aXux9wDaIPK3PG0y2Pfn oCsi+6APrRIFty2HO9oUIDC+a/edSDnzOXLsMGLAk+5bOGpW0BfpczrwmAHwN0KnoJ8WXL 1uq/KJVB9MsFhd8AUbQoLTo4BeR02QQ= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=V6PLoF46; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4B86A43CFC; Thu, 27 Aug 2026 16:00:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 252F31F00A3A; Thu, 27 Aug 2026 16:00:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787846441; bh=nrlTIkFE6/b+AXgWzKleN3cfwGZ9PDfL2MFZp1jZv4Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=V6PLoF46F//II/OdhzDITrpykl+/+mbZDkIJ1ZNNRSekUZU6bmwIaBJz56zGOZ/5Y ne5bquWchpCIPzExXuryY1wCxc1k+4iAzhulroW5fLso0mWRAl/D3RIFffydZ7ZRna b6DU9tM3u0SIIzy/L59PsuwrCKZNt4nre6bTiCdLuE6Nubbah45+V0trbyJEjkOAmw HWK5BHRHASZrz+MJT51IXZSsuraIa6Z1WMePep8glLJ/qkqX6Ta/eg1dOXyhtP0Wf6 Tchx9Mcl3qJwc20YDL5y8vjEEl/JnjlK+NFIkuLCdPlbRSi2LtlVgfUuIMS3wqCYpR 5EwP0YrjgL9wA== Message-ID: <50bb70bc-d442-43df-ab4f-a158c8b05ac7@kernel.org> Date: Thu, 27 Aug 2026 18:00:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 02/18] mm/huge_memory: fix rejection of swap cache folios with a mapping To: kasong@tencent.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Shivam Kalra , Kairui Song References: <20260821-swap-thp-cleanup-v3-0-9b43f5163238@tencent.com> <20260821-swap-thp-cleanup-v3-2-9b43f5163238@tencent.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: <20260821-swap-thp-cleanup-v3-2-9b43f5163238@tencent.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1DFE3180009 X-Stat-Signature: cgzuuafbcyyyj5pfuti3tziqg15ujwyb X-HE-Tag: 1787846441-27582 X-HE-Meta: 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 jlVtmvsE JggHXTLUwHrErQk6pQYyEdu/0XPIdQuQ4Zx5x5ZSjdkm/NHoj05Psv7qarykORUYvY+40SHCPixxJECUeQQBJzvip1YVZordzflOxF3/V1ozxvuRjw6qFMmHq0PtAgRnZKYIx/jT+3IKaUeFrkSsZhgJOQHP8BAQl5w8dwCaLrN60OeWvV+nPxNerbzJvy+Eg9NpNzm5yKcaW6S9TaLFTt2fGTtCex951NPYNAE2zIoYOSZTRCM7Jhi9dPg/KGrJaVH/qv4xXPf6jnJKxidzH8LuBiiyMm767tPjtWJo/NEEAINqD3CZhDDaWfe2E9bDtWtsnFS0u/CpEmwl4gi38wIZVBYKjOr2Juv7n9JyGtyPJ70UQcV+Mw1YHS5o/2OqWNOsP Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/20/26 20:55, Kairui Song via B4 Relay wrote: > From: Kairui Song > > A folio in the swap cache cannot be split if it has a mapping (shmem). > The split code does a defensive check for this in > __folio_freeze_and_split_unmapped, after the folio ref has been frozen > and the NR_SHMEM_THPS/NR_FILE_THPS counters have been decremented. It > rejects the split and returns -EINVAL without unfreezing the folio or > restoring the counters. That error path is buggy: if it is ever taken, > it leaves the folio frozen and stuck, skews the counters, and fires > the VM_WARN_ON_ONCE_FOLIO for a state that is actually legitimate. > > Check for this case up front in folio_check_splittable and return > -EBUSY before any state is modified, so the split routine always backs > out cleanly. > > Also fix a bracket style issue that checkpatch.pl keeps complaining > about. > > Fixes: 00527733d0dc ("mm/huge_memory: add two new (not yet used) functions for folio_split()") > Fixes: 714b056c8321 ("mm/huge_memory: convert VM_BUG* to VM_WARN* in __folio_split") > Reviewed-by: Zi Yan > Signed-off-by: Kairui Song > --- > mm/huge_memory.c | 27 ++++++++++++++++----------- > 1 file changed, 16 insertions(+), 11 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index ced400f72d43..a6759a14e057 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3878,6 +3878,9 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, > int folio_check_splittable(struct folio *folio, unsigned int new_order, > enum split_type split_type) > { > + bool is_anon = folio_test_anon(folio); > + bool is_swapcache = folio_test_swapcache(folio); Both const please. Acked-by: David Hildenbrand (Arm) -- Cheers, David