On Thu, Feb 06, 2020 at 08:37:36AM +0800, Baoquan He wrote: >On 02/06/20 at 08:13am, Baoquan He wrote: >> On 02/06/20 at 07:50am, Wei Yang wrote: >> > On Thu, Feb 06, 2020 at 07:19:45AM +0800, Wei Yang wrote: >> > >On Wed, Feb 05, 2020 at 02:52:51PM +0100, David Hildenbrand wrote: >> > >>Let's use a calculation that's easier to understand and calculates the >> > >>same result. Reusing existing macros makes this look nicer. >> > >> >> > >>We always want to have the number of pages (> 0) to the next section >> > >>boundary, starting from the current pfn. >> > >> >> > >>Suggested-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> >> > >>Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >> > >>Cc: Michal Hocko <mhocko@xxxxxxxxxx> >> > >>Cc: Oscar Salvador <osalvador@xxxxxxx> >> > >>Cc: Baoquan He <bhe@xxxxxxxxxx> >> > >>Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> >> > >>Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> >> > > >> > >Reviewed-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> >> > > >> > >BTW, I got one question about hotplug size requirement. >> > > >> > >I thought the hotplug range should be section size aligned, while taking a >> > >look into current code function check_hotplug_memory_range() guard the range. >> >> A good question. The current code should be block size aligned. I >> remember in some places we assume each block comprise all the sections. >> Can't imagine one or some of them are half section filled. > >I could be wrong, half filled block may not cause problem. > David must be angry about our flooding the mail list :-) Check the code again, there are two memory range check: * check_hotplug_memory_range(), block/section aligned * check_pfn_span(), subsection aligned The second check, check_pfn_span() in __add_pages(), enable the capability to add a memory range with subsection size. This means hotplug still keeps section alignment. BTW, __add_pages() share the same logic as __remove_pages(). Why not change it too? Do I miss something or I don't have the latest source code? -- Wei Yang Help you, Help me
