(2013/11/07 9:54), HATAYAMA Daisuke wrote: > (2013/11/06 11:21), Atsushi Kumagai wrote: >> (2013/11/06 5:27), Vivek Goyal wrote: >>> On Tue, Nov 05, 2013 at 09:45:32PM +0800, Jingbai Ma wrote: >>>> This patch set intend to exclude unnecessary hugepages from vmcore dump file. >>>> >>>> This patch requires the kernel patch to export necessary data structures into >>>> vmcore: "kexec: export hugepage data structure into vmcoreinfo" >>>> http://lists.infradead.org/pipermail/kexec/2013-November/009997.html >>>> >>>> This patch introduce two new dump levels 32 and 64 to exclude all unused and >>>> active hugepages. The level to exclude all unnecessary pages will be 127 now. >>> >>> Interesting. Why hugepages should be treated any differentely than normal >>> pages? >>> >>> If user asked to filter out free page, then it should be filtered and >>> it should not matter whether it is a huge page or not? >> >> I'm making a RFC patch of hugepages filtering based on such policy. >> >> I attach the prototype version. >> It's able to filter out also THPs, and suitable for cyclic processing >> because it depends on mem_map and looking up it can be divided into >> cycles. This is the same idea as page_is_buddy(). >> >> So I think it's better. >> > >> @@ -4506,14 +4583,49 @@ __exclude_unnecessary_pages(unsigned long mem_map, >> && !isAnon(mapping)) { >> if (clear_bit_on_2nd_bitmap_for_kernel(pfn)) >> pfn_cache_private++; >> + /* >> + * NOTE: If THP for cache is introduced, the check for >> + * compound pages is needed here. >> + */ >> } >> /* >> * Exclude the data page of the user process. >> */ >> - else if ((info->dump_level & DL_EXCLUDE_USER_DATA) >> - && isAnon(mapping)) { >> - if (clear_bit_on_2nd_bitmap_for_kernel(pfn)) >> - pfn_user++; >> + else if (info->dump_level & DL_EXCLUDE_USER_DATA) { >> + /* >> + * Exclude the anonnymous pages as user pages. >> + */ >> + if (isAnon(mapping)) { >> + if (clear_bit_on_2nd_bitmap_for_kernel(pfn)) >> + pfn_user++; >> + >> + /* >> + * Check the compound page >> + */ >> + if (page_is_hugepage(flags) && compound_order > 0) { >> + int i, nr_pages = 1 << compound_order; >> + >> + for (i = 1; i < nr_pages; ++i) { >> + if (clear_bit_on_2nd_bitmap_for_kernel(pfn + i)) >> + pfn_user++; >> + } >> + pfn += nr_pages - 2; >> + mem_map += (nr_pages - 1) * SIZE(page); >> + } >> + } >> + /* >> + * Exclude the hugetlbfs pages as user pages. >> + */ >> + else if (hugetlb_dtor == SYMBOL(free_huge_page)) { >> + int i, nr_pages = 1 << compound_order; >> + >> + for (i = 0; i < nr_pages; ++i) { >> + if (clear_bit_on_2nd_bitmap_for_kernel(pfn + i)) >> + pfn_user++; >> + } >> + pfn += nr_pages - 1; >> + mem_map += (nr_pages - 1) * SIZE(page); >> + } >> } >> /* >> * Exclude the hwpoison page. > > I'm concerned about the case that filtering is not performed to part of mem_map > entries not belonging to the current cyclic range. > > If maximum value of compound_order is larger than maximum value of > CONFIG_FORCE_MAX_ZONEORDER, which makedumpfile obtains by ARRAY_LENGTH(zone.free_area), > it's necessary to align info->bufsize_cyclic with larger one in > check_cyclic_buffer_overrun(). > ping, in case you overlooked this... -- Thanks. HATAYAMA, Daisuke
