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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: [PATCH v8 06/30] s390: mm: add PMD swap-exclusive helpers Date: Fri, 2 Oct 2026 02:52:20 -0700 Message-ID: <20261002095503.3585565-7-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261002095503.3585565-1-usama.arif@linux.dev> References: <20261002095503.3585565-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: CB378120003 X-Stat-Signature: gbkzy13b54ayfobsrxtb6qfazq7bh9nb X-Rspam-User: X-HE-Tag: 1790934976-279720 X-HE-Meta: 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 VvlI8sv6 gaz3Hlnj30HBoVbLzXD24NGCOObJQQ8Fv2hyD9dW/xSh+lLLr1/G88SKvcKzaOr9D0cSgKzahLjKlXodBEuNLC9ON8EC0ikVD3KRWoPPcoSndwdUmnMA6l/4GrQZthgrYO6wG59g5IWfoWuurP2x/qa7DaHzYV7PZ5n/OgHG+E0607taw1ztPIll8ZwkOsk+EUVyrdcs/2wys9t5nL84x/GqoVE1lGoRX8WqIbV4D3FOzXu9joU/gwaUtlFQXgexXP+rC Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Prepare for keeping a PMD-mapped anonymous THP mapped by a PMD across the swap round-trip, which makes PG_anon_exclusive have 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, and document it in the RSTE swap layout, where bit 52 was listed as unused. Cc: Alexander Gordeev Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Vasily Gorbik Signed-off-by: Usama Arif --- arch/s390/include/asm/pgtable.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 2d5c2ab06de98..afd886edf0594 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 */ @@ -893,6 +894,21 @@ static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd) } #ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES +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)); +} + #define pmd_swp_soft_dirty(pmd) pmd_soft_dirty(pmd) #define pmd_swp_mksoft_dirty(pmd) pmd_mksoft_dirty(pmd) #define pmd_swp_clear_soft_dirty(pmd) pmd_clear_soft_dirty(pmd) @@ -1900,15 +1916,15 @@ 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). * 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