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s=arc-20220608; d=hostedemail.com; t=1752829415; a=rsa-sha256; cv=none; b=wfKYzo7Cy9Xa6zRmUw/XjyDnStPvrMxljeT1WryQD3nLIhn5KSXlI9D995nnfIYkSyG11G Ge/OYoURR/GzzdcwQii1/t2jliOl5Xw4uHa5/JEbDWvp9V5+byqPszQa3F32yNMj6a28qG NJAEr2v3DgTnhgbGDZ+6LDdRoqS8B7s= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf15.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 58B94176C; Fri, 18 Jul 2025 02:03:27 -0700 (PDT) Received: from MacBook-Pro.blr.arm.com (unknown [10.164.18.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A93ED3F66E; Fri, 18 Jul 2025 02:03:26 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org Cc: ryan.roberts@arm.com, david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, anshuman.khandual@arm.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com, Dev Jain Subject: [PATCH v5 4/7] mm: Introduce FPB_RESPECT_WRITE for PTE batching infrastructure Date: Fri, 18 Jul 2025 14:32:41 +0530 Message-Id: <20250718090244.21092-5-dev.jain@arm.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250718090244.21092-1-dev.jain@arm.com> References: <20250718090244.21092-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 6CBF7A0003 X-Stat-Signature: r35ib5hq3jzt66hriw1jbabcrtcfap8n X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1752829415-919001 X-HE-Meta: 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 RCxU76L2 x5sIg/4hM4uwMFZ+jq2T+dIuwPxeQ8MV3A5utT6LziixDBAJl/d6vay6l9LrP0wASzLx0FOF7HyJ3l84b28iuuGTnfet+Yz2ZqDwqVOWBtAEKoW7iZUFh8Ec+3Qf7cgHShwgGcsowUn4j/+eCdJyvgChTav29H64gnJAuJ6QIj0etjY0cpNnaSultaRRAVE6SvkLKRSmYLKsRNz9rQoRzGWothLRyFldOuhOwU+ThdbWfTi4yuOmxf51HNg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Patch 6 optimizes mprotect() by batch clearing the ptes, masking in the new protections, and batch setting the ptes. Suppose that the first pte of the batch is writable - with the current implementation of folio_pte_batch(), it is not guaranteed that the other ptes in the batch are already writable too, so we may incorrectly end up setting the writable bit on all ptes via modify_prot_commit_ptes(). Therefore, introduce FPB_RESPECT_WRITE so that all ptes in the batch are writable or not. Signed-off-by: Dev Jain --- mm/internal.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 5b0f71e5434b..28d2d5b051df 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -208,17 +208,20 @@ typedef int __bitwise fpb_t; /* Compare PTEs respecting the soft-dirty bit. */ #define FPB_RESPECT_SOFT_DIRTY ((__force fpb_t)BIT(1)) +/* Compare PTEs respecting the writable bit. */ +#define FPB_RESPECT_WRITE ((__force fpb_t)BIT(2)) + /* * Merge PTE write bits: if any PTE in the batch is writable, modify the * PTE at @ptentp to be writable. */ -#define FPB_MERGE_WRITE ((__force fpb_t)BIT(2)) +#define FPB_MERGE_WRITE ((__force fpb_t)BIT(3)) /* * Merge PTE young and dirty bits: if any PTE in the batch is young or dirty, * modify the PTE at @ptentp to be young or dirty, respectively. */ -#define FPB_MERGE_YOUNG_DIRTY ((__force fpb_t)BIT(3)) +#define FPB_MERGE_YOUNG_DIRTY ((__force fpb_t)BIT(4)) static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) { @@ -226,7 +229,9 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) pte = pte_mkclean(pte); if (likely(!(flags & FPB_RESPECT_SOFT_DIRTY))) pte = pte_clear_soft_dirty(pte); - return pte_wrprotect(pte_mkold(pte)); + if (likely(!(flags & FPB_RESPECT_WRITE))) + pte = pte_wrprotect(pte); + return pte_mkold(pte); } /** -- 2.30.2