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Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , 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 v19 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs To: =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= References: <20230615141144.665148-1-usama.anjum@collabora.com> <20230615141144.665148-3-usama.anjum@collabora.com> <1c1beeda-ceed-fdab-bbf5-1881e0a8b102@collabora.com> Content-Language: en-US From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: E8BF014000A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: oyndzmha5ugbxnceea5cgcsagnox48ab X-HE-Tag: 1687428004-48299 X-HE-Meta: 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 af38aQEQ fDaAHf5BPH/+gQ81tBKlgyr2PQhQ+YfXgRjBGF8mnrv/N6Fw8cEJU3TDNDCVCs+o0e4xzeoOWVJTEYga5Uxk9qXTh8IkdImzO8x4XEcpTmZcrdmHbJURruTnRlaczyoICZ1mcrdLRHDVNr57QGZXyO+fltBjEQAduW+Tzeir5P0um+OA9e8nWGO20iH47e/qmZNZ80PwaIv/EbJUXcI/6YICYGiNfYp/Z1KgU3iD707vxld5vbMU0KlSd92ZHPZMC8Y3VJOKPnHJrJUEk7EJcM5YpV7OOp8ue2GXVmV61wrUpSRiqgnOHACrHGA== 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 6/21/23 6:29 PM, Michał Mirosław wrote: > On Wed, 21 Jun 2023 at 08:35, Muhammad Usama Anjum > wrote: >> On 6/20/23 11:03 PM, Andrei Vagin wrote: >> ... >>>> +struct pagemap_scan_private { >>>> + struct page_region *vec_buf, cur_buf; >>>> + unsigned long long vec_buf_len, vec_buf_index, max_pages, found_pages, flags; >>> >>> should it be just unsigned long? >> These internal values are storing data coming from user in struct >> pm_scan_arg in which all variables are 64 bit(__u64) explicitly. This is >> why we have unsigned long long here. It is absolutely necessary. > > vec_buf_len and vec_buf_index can only have values in 0..512 range. > flags has only a few lower bits defined (this is checked on ioctl > entry) and max_pages can be limited to ULONG_MAX. Actually putting `if > (!max_pages || max_pages > ULONG_MAX) max_pages = ULONG_MAX` would > avoid having to check !max_pages during the walk. I'll update. > > Best Regards > Michał Mirosław -- BR, Muhammad Usama Anjum