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 B577EC982D7 for ; Fri, 18 Sep 2026 21:41:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CBC176B008C; Fri, 18 Sep 2026 17:41:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C3F3D6B0093; Fri, 18 Sep 2026 17:41:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE2056B0095; Fri, 18 Sep 2026 17:41:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 814096B008C for ; Fri, 18 Sep 2026 17:41:42 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 08ED180311 for ; Fri, 18 Sep 2026 21:41:42 +0000 (UTC) X-FDA: 85228205244.06.B3AD6A3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf11.hostedemail.com (Postfix) with ESMTP id 40EA840007 for ; Fri, 18 Sep 2026 21:41:40 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="Oj2p/kVF"; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1789767700; 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=PeNqrRYaLm5sJCyL+8qRVNEQneIa27x2hQRJJB+Kd7I=; b=nSobekxqViioXwJY1E0fxLZcbflQkrGimEPKl0KFCBoIUFcZTSYxaFHFppHpy7DnQVnew0 OO4G0Lu40RLbR6EpSRiUazxIg5T/Ym+n+OHZeCRIdDrpeN+GnuJL2czGn0wb6wrase5yTr m/UFpP7/s6qr4vvkLaOuA9jBkcgVmlQ= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="Oj2p/kVF"; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1789767700; b=FL8YJHUx91+O2RJdyTNgffI7lsvOSvnYsDQK0aduYSgF6yL//Q3QS2TMH2frc2j++J33t4 LfQOXiVlKaHoiTTD8/+mvlauim6dCED0kC8+sarSrrTztSrln8C7rm7NliO3VmownKYN/Q +32V3Gc7eHJ8PS4sxeIsnmvmWAr7pOU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id BD2C06053B; Fri, 18 Sep 2026 21:41:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 808B91F000FF; Fri, 18 Sep 2026 21:41:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789767699; bh=PeNqrRYaLm5sJCyL+8qRVNEQneIa27x2hQRJJB+Kd7I=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Oj2p/kVFBTo4rNCg3ja/p7FHen560WeDm0VQ17VhhVE627tVA3a9rcWf8FwWkDiBx YZ0PVffkg7aIdn73zU4yaQPxj5enoT9s9f4KDiHEFELBjXFdNAogRv09ocbsYhFSV/ 9YVro2p1s0S/yIlmNWCjL3EG32QmyfClqu6EOHG0zy/Ma8sOcnq0n3PNrQpzCR0M4k GZ26ZGZ6eQW9pmGjZijM3MwMbWe30oX5T2Ziexnq5FrL0BCjcLmI9mEDqby0vI4mLN +P+SCP52qV7tqYPC3e3Ht3QOeSS1EkBBrGKTfDHHrja/Zi9IkgYK8CzuYZ6jInsIQS y7q+sxyLIn9kQ== Message-ID: <92d0078e-afdc-422a-b624-0a3ca9aa307c@kernel.org> Date: Fri, 18 Sep 2026 23:41:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND v7 06/29] s390: mm: add PMD swap-exclusive helpers To: Usama Arif , Andrew Morton , chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org Cc: ying.huang@linux.alibaba.com, Baoquan He , willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, Nico Pache , "Liam R. Howlett" , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com, Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik References: <20260914122950.3283997-1-usama.arif@linux.dev> <20260914122950.3283997-7-usama.arif@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: <20260914122950.3283997-7-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 40EA840007 X-Stat-Signature: 56idf96a5pzu6wno89myacqgrqw597ui X-Rspam-User: X-HE-Tag: 1789767700-664887 X-HE-Meta: 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 FMKd/I/J q0kIGRlGCzX4Bvi0YV/VN9+QUQMPU8ulLy6ks6rg3jE71FKn8g5LeyYUvMOxyU1y7MNyoApKsM+LV3DCDv5pnGOBtKuvOKu8sDCl3G9Lp92qVG7asPrAJskJL4bhzzQM7yYwZKZMa3YbX1hBDNglHjG+jIx7TV9rmU7NXH+tFH0OQiTs79Pm8IWFF8tRxYtFr10BxtQFPXtgswSN40LfbtF9YyVQ4OWkMYTYnOYMOT07GbXojZm28cmsCLaVLsSBSt6182jq8q3o3ePo83w4v211C2lvalRziFI4H Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/14/26 14:27, Usama Arif wrote: > A later patch keeps a PMD-mapped anonymous THP mapped by a PMD across the > swap round-trip, so PG_anon_exclusive now has to survive in a swap PMD and > not just in a swap PTE. > > s390 is the one architecture where a swap PMD is not a swap PTE in > disguise: it is an RSTE with its own layout, converted to a fake PTE swap > entry for the common code. Give it its own exclusive bit rather than > borrowing the PTE-format macro. The two happen to have the same value, but > that is a coincidence. Bit 52 was documented as unused; document what it > is now. > > Cc: Alexander Gordeev > Cc: Gerald Schaefer > Cc: Heiko Carstens > Cc: Vasily Gorbik > Signed-off-by: Usama Arif > --- > arch/s390/include/asm/pgtable.h | 28 ++++++++++++++++++++++++++-- > 1 file changed, 26 insertions(+), 2 deletions(-) > > diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h > index 2d5c2ab06de98..0790a0884cfab 100644 > --- a/arch/s390/include/asm/pgtable.h > +++ b/arch/s390/include/asm/pgtable.h > @@ -333,6 +333,7 @@ void setup_protection_map(void); > /* Common bits in region and segment table entries, for swap entries */ > #define _RST_ENTRY_COMM 0x0010 /* Common-Region/Segment, marks swap entry */ > #define _RST_ENTRY_INVALID 0x0020 /* invalid region/segment table entry */ > +#define _RST_ENTRY_SWP_EXCLUSIVE 0x0800 /* SW exclusive swap bit, see mk_swap_rste() */ > > #define _CRST_ENTRIES 2048 /* number of region/segment table entries */ > #define _PAGE_ENTRIES 256 /* number of page table entries */ > @@ -859,6 +860,28 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) > return clear_pte_bit(pte, __pgprot(_PAGE_SWP_EXCLUSIVE)); > } > > +#ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES > +/* > + * A PMD swap entry is an RSTE, not a PTE, so it needs its own exclusive bit > + * rather than the PTE-format _PAGE_SWP_EXCLUSIVE. The two happen to have the > + * same value; see the RSTE swap layout above mk_swap_rste(). > + */ I'm not sure the documentation here is warranted. It's all documented above above __SWP_OFFSET_MASK_RSTE, no? I'd just extend the documentation there and keep it away from these helpers that just use the bit. The fact that they use the same bit doesn't really matter. > +static inline pmd_t pmd_swp_mkexclusive(pmd_t pmd) > +{ > + return set_pmd_bit(pmd, __pgprot(_RST_ENTRY_SWP_EXCLUSIVE)); > +} > + > +static inline bool pmd_swp_exclusive(pmd_t pmd) > +{ > + return pmd_val(pmd) & _RST_ENTRY_SWP_EXCLUSIVE; > +} > + > +static inline pmd_t pmd_swp_clear_exclusive(pmd_t pmd) > +{ > + return clear_pmd_bit(pmd, __pgprot(_RST_ENTRY_SWP_EXCLUSIVE)); > +} > +#endif I guess we could move it above the pmd_swp_soft_dirty() stuff in the same CONFIG_ARCH_HAS_PMD_SOFTLEAVES block. > + > static inline int pte_soft_dirty(pte_t pte) > { > return pte_val(pte) & _PAGE_SOFT_DIRTY; > @@ -1900,15 +1923,16 @@ static inline swp_entry_t __swp_entry(unsigned long type, unsigned long offset) > * Bits 59 and 63 are used to indicate the swap entry. Bit 58 marks the rste > * as invalid. > * A swap entry is indicated by bit pattern (rste & 0x011) == 0x010 > - * | offset |Xtype |11TT|S0| > + * | offset |Etype |11TT|S0| > * |0000000000111111111122222222223333333333444444444455|555555|5566|66| > * |0123456789012345678901234567890123456789012345678901|234567|8901|23| > * > * Bits 0-51 store the offset. > + * Bit 52 (E) is used to remember PG_anon_exclusive > + * (_RST_ENTRY_SWP_EXCLUSIVE), mirroring bit 52 of a swap pte. > * Bits 53-57 store the type. > * Bit 62 (S) is used for softdirty tracking. > * Bits 60-61 (TT) indicate the table type: 0x01 for REGION3 and 0x00 for SEGMENT. > - * Bit 52 (X) is unused. > */ > > #define __SWP_OFFSET_MASK_RSTE ((1UL << 52) - 1) IIRC, __pmd_to_swp_entry() and __swp_entry_to_pmd() will lose the flag, which is the right thing to do. So conceptually LGTM. -- Cheers, David