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Shutemov" , Lorenzo Stoakes , Uladzislau Rezki , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev, kernel test robot Subject: Re: [PATCH v2 5/5] mm: ptep_deref() conversion Date: Thu, 18 May 2023 17:22:11 +0000 Message-Id: <20230518172211.84101-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230518110727.2106156-6-ryan.roberts@arm.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1B0ED20007 X-Stat-Signature: ipsiuhjbo9gnu79ni1qim7sf5owd41cb X-Rspam-User: X-HE-Tag: 1684430534-586688 X-HE-Meta: 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 zXVbH0Jx 6oORQZAWtohlFS325sFCq6zTKrWjlZagvNX+zK265hXoSRIlKwZYdKtQL7w5MBmm5/8hDPk9c0k7jCLAxJCGjugvevhsQvAZwqQABaEyVBmq2ntzIgeuORNwZL/GbTmAQWQy6L3i6+ppPHhfOZfJySvt4kdb351Fm2evyi6+mk53eR7r5tFX25z+lprWNNFCRAQT4QeaDNL/q+Grqit+2htFfQYHQzhs3q5guS2CcREsKshAXCYr9mwiC7/K6nOM3QVXcD/vR7LaBD01nuRT9ScL7zBQ3e+mcduIQ2LYtQO+d57UszwBPHR8pT5soTlF635085soUBeZwRSEVALoW/zFXLq+vVZanmYHDmSCl9p0epW8+d3A3GzmmUML5BKW1lyU1Uw81GRBUXeqh/PHlQlJT7arnRmXzRPl8XOgzcN5SPbuZ9Dt0puNfFHWizdAgMz+4V9lhV+dyfhwSw8cUk6l3YA== 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: On Thu, 18 May 2023 12:07:27 +0100 Ryan Roberts wrote: > Convert all instances of direct pte_t* dereferencing to instead use > ptep_deref() helper. By default, the helper does a direct dereference as > before, but it can (and will) be overridden by the architecture to fully > encapsulate the contents of the pte. Arch code is deliberately not > converted, as the arch code knows best. > > Conversion was done using Coccinelle: > > ---- > > // $ make coccicheck \ > // COCCI=ptepderef.cocci \ > // SPFLAGS="--include-headers" \ > // MODE=patch > > virtual patch > > @ depends on patch @ > pte_t *v; > @@ > > - *v > + ptep_deref(v) > > ---- > > Then reviewed and hand-edited to avoid multiple unnecessary calls to > ptep_deref(), instead opting to store the result of a single in a > variable, where it is correct to do so. This will benefit arch-overrides > that may be more complex than a simple (optimizable) pointer > dereference. > > Included is a fix for an issue in an earlier version of this patch that > was pointed out by kernel test robot. The issue arose because config > MMU=n elides definition of the ptep helper functions, including > ptep_deref(). HUGETLB_PAGE=n configs still define a simple > huge_ptep_clear_flush() for linking purposes, which dereferences the > ptep. So when both configs are disabled, this caused a build error > because ptep_deref() is not defined. Fix by continuing to do a direct > dereference when MMU=n. This is safe because for this config the arch > code cannot be trying to virtualize the ptes because none of the ptep > helpers are defined. > > Reported-by: kernel test robot > Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/ > Signed-off-by: Ryan Roberts [...] > mm/damon/ops-common.c | 2 +- > mm/damon/paddr.c | 2 +- > mm/damon/vaddr.c | 10 +- For above mm/damon/ part, Reviewed-by: SeongJae Park Thanks, SJ