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Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , 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 v10 3/6] fs/proc/task_mmu: Implement IOCTL to get and/or the clear info about PTEs Content-Language: en-US To: Mike Rapoport References: <20230202112915.867409-1-usama.anjum@collabora.com> <20230202112915.867409-4-usama.anjum@collabora.com> From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 5F702A0019 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: i5fjhc3k4f7mpr8nwjuue5eshfzwqzch X-HE-Tag: 1676962951-548132 X-HE-Meta: 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 sT5kipK0 w55eS6Sc8do2bT6q2/Ao7Cql7AYVtM05fbyS8QT1Lfpg11nW/4G7ulnUS36z/23WlSDUnqQ0MymSQ+UYo0waRmUZCdwX3fGlSPzl+5F9zRJeDUR+WKqIQ5/zw/SOg0eb5PLg0iRvWMZHuB5V+9Vm2emiZoCfzx01yRoBV/JVHb81zmC1ma6z76daJwg0sPapIZ9rjvhNhrmFyxeZhM4acyWGPqZ1A1BmME4XjpR9PX5gAE8VHAVUy7PUG/nRK/CVppr1BeqSjcDh8ayI= 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 2/20/23 6:26 PM, Mike Rapoport wrote: > Hi, > > On Thu, Feb 02, 2023 at 04:29:12PM +0500, Muhammad Usama Anjum wrote: >> This IOCTL, PAGEMAP_SCAN on pagemap file can be used to get and/or clear >> the info about page table entries. The following operations are supported >> in this ioctl: >> - Get the information if the pages have been written-to (PAGE_IS_WRITTEN), >> file mapped (PAGE_IS_FILE), present (PAGE_IS_PRESENT) or swapped >> (PAGE_IS_SWAPPED). >> - Write-protect the pages (PAGEMAP_WP_ENGAGE) to start finding which >> pages have been written-to. >> - Find pages which have been written-to and write protect the pages >> (atomic PAGE_IS_WRITTEN + PAGEMAP_WP_ENGAGE) >> >> +/* >> + * struct pagemap_scan_arg - Pagemap ioctl argument >> + * @start: Starting address of the region >> + * @len: Length of the region (All the pages in this length are included) >> + * @vec: Address of page_region struct array for output >> + * @vec_len: Length of the page_region struct array >> + * @max_pages: Optional max return pages >> + * @flags: Flags for the IOCTL >> + * @required_mask: Required mask - All of these bits have to be set in the PTE >> + * @anyof_mask: Any mask - Any of these bits are set in the PTE >> + * @excluded_mask: Exclude mask - None of these bits are set in the PTE >> + * @return_mask: Bits that are to be reported in page_region >> + */ >> +struct pagemap_scan_arg { >> + __u64 start; >> + __u64 len; >> + __u64 vec; >> + __u64 vec_len; >> + __u32 max_pages; >> + __u32 flags; >> + __u64 required_mask; >> + __u64 anyof_mask; >> + __u64 excluded_mask; >> + __u64 return_mask; >> +}; > > After Nadav's comment I've realized I missed the API part :) > > A few quick notes for now: > * The arg struct is fixed, so it would be impossible to extend the API > later. Following the clone3() example, I'd add 'size' field to the > pagemam_scan_arg so that it would be possible to add new fields afterwards. > * Please make flags __u64, just in case > * Put size and flags at the beginning of the struct, e.g. > > strucr pagemap_scan_arg { > size_t size; > __u64 flags; > /* all the rest */ > }; Updated. Thank you so much! > >> + >> +/* Special flags */ >> +#define PAGEMAP_WP_ENGAGE (1 << 0) >> + >> #endif /* _UAPI_LINUX_FS_H */ >> -- >> 2.30.2 >> > -- BR, Muhammad Usama Anjum