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b=bShHqSnI6oWOfUDSbW6cYy9eMbRTgUko/xyPhiYjQd4+q8UgRyl4FX9sU96QojKmj 7jK6GH6Y5DzVZNl/oYRof/zwlsdAgIq4fxxaZFx4NGJtrqT4D5dnzx3nfJWfCBYTOo qOhK6VyjprDy5b4PtURtf5opb1bLBCMSUX9BCEzhGEFgCit94GdQXXSZ8nj/J1X447 DHVTof/qqRgiYNi6dpMLHS0InhtO5TGWFhmblbiv2yVcqPhabshMvd3rR4d7/yfzL6 CUrw06X/S8BL4t3f+hrAxCmBx9mGTYM7AciY6l3xlakeFNLHf3tkdeUpikDVPqcxDZ IOF2V8sJaovvQ== From: Tejun Heo To: bot+bpf-ci@kernel.org, Catalin Marinas , Will Deacon , Alexei Starovoitov Cc: david@kernel.org, arighi@nvidia.com, memxor@gmail.com, akpm@linux-foundation.org, rppt@kernel.org, andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, emil@etsalapatis.com, void@manifault.com, changwoo@igalia.com, clm@meta.com, ihor.solodrai@linux.dev, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next] arm64: mm: Complete the PTE store in ptep_try_set() Date: Sun, 07 Jun 2026 10:04:19 -1000 Message-Id: <1780862659.ccb18e27e916dc4b@kernel.org> In-Reply-To: <5f68f44310d4878185fd5ebc52d66530b99f174c6d04ab1170dc53cefaa54568@mail.kernel.org> References: <088f52fd25860ca961449d53f91b214a@kernel.org> <5f68f44310d4878185fd5ebc52d66530b99f174c6d04ab1170dc53cefaa54568@mail.kernel.org> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1598A20008 X-Stat-Signature: rqd3gaby4me1zajf6o8fkd8gp4tcnpib X-Rspam-User: X-HE-Tag: 1780863036-16754 X-HE-Meta: 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 PBlNcSTJ QVDI/jdPMT2PruxyfLYImrVsm1kZ7nG9q/CVeuwRX4C9QKywiO/dnLrEGCpuGEiU64vOljAeOUqFHhmTTi6uyF9x+ukqZEGZ3RktCQv8e6V4o4p2msAPWwsLoKsYR0DpquM8FhA5HD1XEAqkoENQ07rkVMzvezXXXxFFMjAf/MpqQIj/ywIruMS+wVhYmt0hVYRZx438XXRr0Bcft7Gvye4PgsJecb0i569cHnuRc3BdI+XI0FgpPH3Ec4ELi2wwD9amYwCDAZoz2Mkihj9Je0OQpxEHPjQ8kCIUL6hEI9WDP+eau+xFPl9QPsMJ7b9STuua0tY5w21HUaK5H3AArkWYW/Fp8HFL3hx9TU5RxMxB7ePProsd8QBVvBzGRHt3gZq5GGc7T2ORlobU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Can this path actually loop, or is the deferred barrier guaranteed to be > flushed before the faulting instruction is retried? I don't know the arm64 paths well enough to say. What I can see is that ptep_try_set() only runs as an apply_to_page_range() callback, and apply_to_pte_range() brackets it with lazy_mmu_mode_enable()/disable(), with the disable() flushing TIF_LAZY_MMU_PENDING before returning. The barriers would land before the access is retried. It also looks like the same queue_pte_barriers() path __set_pte() already uses. I'd defer to Catalin and the arm64 folks on whether that actually closes the case. Thanks. -- tejun