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b=FZf2EeJJ6CouBH6dRTWD5QsUvu9R3Y07IbzYK07NwD+++5qyZCtALlGTRkvPB+hXt zLBKijKwOL2hxP7kTb5To4l1qhBfIH8HtO7M+oCRF3oMgRGX6pjZFGoiSQ8LuEbBlZ WcH1AXyh3AzZKg8yjcaUWUKRR7cR5BGNf1lXMaeYg965CM0Ulpk3A6XmR83hQ1F4Be OfnOIglB5tWnXi1evVJ6Y28aiI2ZwIgEgvplefN8OiRDawY1S/9FGjP7Bj+Zmxuq2A uFDJeCCmkpcuyueMUrdjd8t0jN7HDFWmmfxClAqRnHYYsjD4azcBVoeTEuwgez3+zl +s/HsbvnwNdIA== From: Will Deacon To: akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Barry Song Cc: catalin.marinas@arm.com, kernel-team@android.com, Will Deacon , david@redhat.com, ardb@kernel.org, jhubbard@nvidia.com, mark.rutland@arm.com, Ryan Roberts Subject: Re: [PATCH v2] mm: arm64: document why pte is not advanced in contpte_ptep_set_access_flags() Date: Fri, 6 Sep 2024 13:29:26 +0100 Message-Id: <172562211364.1176080.6213351630477902092.b4-ty@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240905081124.9576-1-21cnbao@gmail.com> References: <20240905081124.9576-1-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 4E9C61C000D X-Stat-Signature: 18567dqxs67kemorqdq5oz6jyk4e57f9 X-Rspam-User: X-HE-Tag: 1725625776-927599 X-HE-Meta: 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 3zaPOgVP ZuqoDyYwTpb7LzSriLWtcRYBZ1d+YdlpkigoYp8oVAIDOOuaH+JSt2zxItQCBkJn+6W4Go0Ohr6UNMV86KKaXIiwrGaVInbZUoa52k3/QhEJMCv3tKB0s/rkvDgegApTNbjbFhCV+VzECqWdNfWNHpGfeDBNjhtFXWC3TuSorolbckb1XZq6f1i/cyaxnfndi4MSnGzEZfLZLlnT5TW1uN1GEbW2SXhN5h/F7dPKEjQwLGTqZvb1+yiVo/zGF6cZUOyDSMvbIU3GpJ6gevIMYvT3snXOtzlsjppEo/6jHTXUrmRIOFiN+mWxyvOmBKiGjFqxTO8FLOj/CY6YCNQfS0JFeMmq2ARjxH4VM1PsUAaPZckueD4P/QXpiD90XtzYWIzcq 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: On Thu, 05 Sep 2024 20:11:24 +1200, Barry Song wrote: > According to David and Ryan, there isn't a bug here, even though we > don't advance the PTE entry, because __ptep_set_access_flags() only > uses the access flags from the entry. > > However, we always check pte_same(pte, entry) using the first entry > in __ptep_set_access_flags(). This means that the checks from 1 to > nr - 1 are not comparing the same PTE indexes (thus, they always > return false), which can be a bit confusing. To clarify the code, let's > add some comments. > > [...] Applied to arm64 (for-next/mm), thanks! [1/1] mm: arm64: document why pte is not advanced in contpte_ptep_set_access_flags() https://git.kernel.org/arm64/c/70565f2be880 Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev