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[70.30.145.63]) by smtp.gmail.com with ESMTPSA id s133-20020a37a98b000000b00706afbdeb01sm1799074qke.8.2023.01.24.09.30.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 09:30:34 -0800 (PST) Date: Tue, 24 Jan 2023 12:30:32 -0500 From: Peter Xu To: Muhammad Usama Anjum Cc: David Hildenbrand , Andrew Morton , =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Andrei Vagin , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , Mike Rapoport , Nadav Amit , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: Re: [PATCH v7 3/4] fs/proc/task_mmu: Implement IOCTL to get and/or the clear info about PTEs Message-ID: References: <20230109064519.3555250-1-usama.anjum@collabora.com> <20230109064519.3555250-4-usama.anjum@collabora.com> <31b71791-66b0-c2d8-81da-e17eff5ffbe8@collabora.com> MIME-Version: 1.0 In-Reply-To: <31b71791-66b0-c2d8-81da-e17eff5ffbe8@collabora.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1D69040027 X-Stat-Signature: kn1witymhcwa8iwh94r8mgpz5ai76rbn X-HE-Tag: 1674581437-742260 X-HE-Meta: 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 4Nj0hErm ClXSkUwbIOVTacfRET5zvQmJIqImBiBv0VwvMiM3hSbU7InqLyz50UYg7HlAmQ2kb5mOmeSqZQ7COuulXA8zurG816ST/2tYIFVGzrU3nxmISPyZRQha4DDadgcM4QOG6rnYG0IlTfOojN6O90VkOT/8Jjc1eX+5QK33urZhOJ2vK0p3whKK3eDuV9+i/dPhKw4SAZi5Br2IUMeYVXB5TdtPDF3jxWltZlbF19dHUmAwAmcbUruv5NgPFE2XVBlqzbfIuMhq1ePfe7KXXSPAEovmZWxscQ6PRVwQ6gU2iHI8XJv4D3dbbvYKo6xt7s3Bt0tyCAs6Df3FfHLSP+VoqATvOQwVhq3+mmjtTgl0ir/LofoElDiZ8iX2kKXgL5mh4GQrl5tNQyK2yB5vtAYVCLKh2YdlfmRo8KUV6yfHgf7PrBxQ= 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 Mon, Jan 23, 2023 at 05:18:13PM +0500, Muhammad Usama Anjum wrote: > >> + if (IS_GET_OP(p) && p->max_pages && (p->found_pages == p->max_pages)) > >> + return -ENOSPC; > > > > This is the function to test "whether the walker should walk the vma > > specified". This check should IIUC be meaningless because found_pages > > doesn't boost during vma switching, while OTOH your pmd walker fn should do > > proper check when increasing found_pages and return -ENOSPC properly when > > the same condition met. That should be enough, IMHO. > This check is needed in case we want to abort the walk at once. We return > negative value from here which aborts the walk. Returning negative value > from pmd_entry doesn't abort the walk. So this check is needed in the > test_walk. Why? What I see locally is (walk_pmd_range): if (ops->pmd_entry) err = ops->pmd_entry(pmd, addr, next, walk); if (err) break; Thanks, -- Peter Xu