On Wed, 09 Jan 2019 16:36:36 +0530 Arun KS <arunks@xxxxxxxxxxxxxx> wrote: > On 2019-01-09 16:27, Michal Hocko wrote: > > On Wed 09-01-19 16:12:48, Arun KS wrote: > > [...] > >> It will be called once per online of a section and the arg value is > >> always > >> set to 0 while entering online_pages_range. > > > > You rare right that this will be the case in the most simple scenario. > > But the point is that the callback can be called several times from > > walk_system_ram_range and then your current code wouldn't work > > properly. > > Thanks. Will use += The v8 patch https://lore.kernel.org/lkml/1547032395-24582-1-git-send-email-arunks@xxxxxxxxxxxxxx/T/#u (which you apparently sent 7 minutes after typing the above) still has static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, void *arg) { - unsigned long i; unsigned long onlined_pages = *(unsigned long *)arg; - struct page *page; if (PageReserved(pfn_to_page(start_pfn))) - for (i = 0; i < nr_pages; i++) { - page = pfn_to_page(start_pfn + i); - (*online_page_callback)(page); - onlined_pages++; - } + onlined_pages = online_pages_blocks(start_pfn, nr_pages); Even then the code makes no sense. static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, void *arg) { unsigned long onlined_pages = *(unsigned long *)arg; if (PageReserved(pfn_to_page(start_pfn))) onlined_pages += online_pages_blocks(start_pfn, nr_pages); online_mem_sections(start_pfn, start_pfn + nr_pages); *(unsigned long *)arg += onlined_pages; return 0; } Either the final assignment should be *(unsigned long *)arg = onlined_pages; or the initialization should be unsigned long onlined_pages = 0; This is becoming a tad tiresome and I'd prefer not to have to check up on such things. Can we please get this right?
