From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 848DA46D559 for ; Mon, 14 Sep 2026 12:31:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789389069; cv=none; b=exLbaQlSVDrRxi/zskalh/Noy/tZltLP1+Mh2xTRQHWgaVTNHwteXwR9tVJv00Qe0NvQQy2oJ0rwofPZqFeSkP9KeMUQ6/W7zIxSWPNVW1AQxcZDb+2ZraXXAJUYkVH/foN7PpS2LMxg+xi7cZxwsxLgypB0j3fCng/UbdQXaDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789389069; c=relaxed/simple; bh=N+dRbJAiKiCxpTGr27ho63g/6orT5YaFsO8QYoCGDoE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=L3rIurcvRpJnyR5vqYdaWzqDkYO6uriOauzfrhlN9tiGTIuN8nkGWzkMbaBd6Xh2PsJLVlwuDHwC7MOrZ5Cwoq21/zwVR+5BOKx7uJvjok7zQc0TUiM1F5guQr81VHtL7IrrF8mV/vMrNZfhXDXFf/Sf+5B8AcqStnPUE0LfMig= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=xsshYLyb; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="xsshYLyb" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=N+dRbJAiKiCxpTGr27ho63g/6orT5YaFsO8QYoCGDoE=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789389060; v=1; x=1789993860; b=xsshYLyb7yw87oCEK62zbNZcv//TVBLxEepVmEoW0YB7QmLIypzANdkvMPRjVIXWWWjxiYNK UivxatneTWdGrNfxO8AspBkSS6a3BqCVv9s+3yIXSja40/jjFR0hT91pUGe8Gok4Cu+3o6/wwNl VbAA7xil+5NUO23i9i8RP2Ak= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id ffd5ef34c1221106; Mon, 14 Sep 2026 12:31:00 +0000 X-Mizu-Trace-ID: ffd5ef34c1221106 X-Migadu-Flow: FLOW_OUT From: Usama Arif To: Andrew Morton , david@kernel.org, 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, Usama Arif , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik Subject: [RESEND v7 06/29] s390: mm: add PMD swap-exclusive helpers Date: Mon, 14 Sep 2026 05:27:56 -0700 Message-ID: <20260914122950.3283997-7-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260914122950.3283997-1-usama.arif@linux.dev> References: <20260914122950.3283997-1-usama.arif@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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(). + */ +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 + 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) -- 2.53.0-Meta