> Linux marks pages that are logically offline via a page flag (map count). > Such pages e.g. include pages infated as part of a balloon driver or > pages that were not actually onlined when onlining the whole section. > > While the hypervisor usually allows to read such inflated memory, we > basically read and dump data that is completely irrelevant. Also, this > might result in quite some overhead in the hypervisor. In addition, > we saw some problems under Hyper-V, whereby we can crash the kernel by > dumping, when reading memory of a partially onlined memory segment > (for memory added by the Hyper-V balloon driver). > > Therefore, don't read and dump pages that are marked as being logically > offline. > > Signed-off-by: David Hildenbrand <da...@redhat.com>
Thanks for the v2 update. I'm going to merge this patch after the kernel patches are merged and it tests fine with the kernel. Kazu > --- > > v1 -> v2: > - Fix PAGE_BUDDY_MAPCOUNT_VALUE vs. PAGE_OFFLINE_MAPCOUNT_VALUE > > makedumpfile.c | 34 ++++++++++++++++++++++++++++++---- > makedumpfile.h | 1 + > 2 files changed, 31 insertions(+), 4 deletions(-) > > diff --git a/makedumpfile.c b/makedumpfile.c > index 8923538..a5f2ea9 100644 > --- a/makedumpfile.c > +++ b/makedumpfile.c > @@ -88,6 +88,7 @@ mdf_pfn_t pfn_cache_private; > mdf_pfn_t pfn_user; > mdf_pfn_t pfn_free; > mdf_pfn_t pfn_hwpoison; > +mdf_pfn_t pfn_offline; > > mdf_pfn_t num_dumped; > > @@ -249,6 +250,21 @@ isHugetlb(unsigned long dtor) > && (SYMBOL(free_huge_page) == dtor)); > } > > +static int > +isOffline(unsigned long flags, unsigned int _mapcount) > +{ > + if (NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE) == NOT_FOUND_NUMBER) > + return FALSE; > + > + if (flags & (1UL << NUMBER(PG_slab))) > + return FALSE; > + > + if (_mapcount == (int)NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE)) > + return TRUE; > + > + return FALSE; > +} > + > static int > is_cache_page(unsigned long flags) > { > @@ -2287,6 +2303,8 @@ write_vmcoreinfo_data(void) > WRITE_NUMBER("PG_hwpoison", PG_hwpoison); > > WRITE_NUMBER("PAGE_BUDDY_MAPCOUNT_VALUE", PAGE_BUDDY_MAPCOUNT_VALUE); > + WRITE_NUMBER("PAGE_OFFLINE_MAPCOUNT_VALUE", > + PAGE_OFFLINE_MAPCOUNT_VALUE); > WRITE_NUMBER("phys_base", phys_base); > > WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR); > @@ -2687,6 +2705,7 @@ read_vmcoreinfo(void) > READ_SRCFILE("pud_t", pud_t); > > READ_NUMBER("PAGE_BUDDY_MAPCOUNT_VALUE", PAGE_BUDDY_MAPCOUNT_VALUE); > + READ_NUMBER("PAGE_OFFLINE_MAPCOUNT_VALUE", PAGE_OFFLINE_MAPCOUNT_VALUE); > READ_NUMBER("phys_base", phys_base); > #ifdef __aarch64__ > READ_NUMBER("VA_BITS", VA_BITS); > @@ -6041,6 +6060,12 @@ __exclude_unnecessary_pages(unsigned long mem_map, > else if (isHWPOISON(flags)) { > pfn_counter = &pfn_hwpoison; > } > + /* > + * Exclude pages that are logically offline. > + */ > + else if (isOffline(flags, _mapcount)) { > + pfn_counter = &pfn_offline; > + } > /* > * Unexcludable page > */ > @@ -7522,7 +7547,7 @@ write_elf_pages_cyclic(struct cache_data *cd_header, > struct cache_data *cd_page) > */ > if (info->flag_cyclic) { > pfn_zero = pfn_cache = pfn_cache_private = 0; > - pfn_user = pfn_free = pfn_hwpoison = 0; > + pfn_user = pfn_free = pfn_hwpoison = pfn_offline = 0; > pfn_memhole = info->max_mapnr; > } > > @@ -8804,7 +8829,7 @@ write_kdump_pages_and_bitmap_cyclic(struct cache_data > *cd_header, struct cache_d > * Reset counter for debug message. > */ > pfn_zero = pfn_cache = pfn_cache_private = 0; > - pfn_user = pfn_free = pfn_hwpoison = 0; > + pfn_user = pfn_free = pfn_hwpoison = pfn_offline = 0; > pfn_memhole = info->max_mapnr; > > /* > @@ -9749,7 +9774,7 @@ print_report(void) > pfn_original = info->max_mapnr - pfn_memhole; > > pfn_excluded = pfn_zero + pfn_cache + pfn_cache_private > - + pfn_user + pfn_free + pfn_hwpoison; > + + pfn_user + pfn_free + pfn_hwpoison + pfn_offline; > shrinking = (pfn_original - pfn_excluded) * 100; > shrinking = shrinking / pfn_original; > > @@ -9763,6 +9788,7 @@ print_report(void) > REPORT_MSG(" User process data pages : 0x%016llx\n", pfn_user); > REPORT_MSG(" Free pages : 0x%016llx\n", pfn_free); > REPORT_MSG(" Hwpoison pages : 0x%016llx\n", pfn_hwpoison); > + REPORT_MSG(" Offline pages : 0x%016llx\n", pfn_offline); > REPORT_MSG(" Remaining pages : 0x%016llx\n", > pfn_original - pfn_excluded); > REPORT_MSG(" (The number of pages is reduced to %lld%%.)\n", > @@ -9790,7 +9816,7 @@ print_mem_usage(void) > pfn_original = info->max_mapnr - pfn_memhole; > > pfn_excluded = pfn_zero + pfn_cache + pfn_cache_private > - + pfn_user + pfn_free + pfn_hwpoison; > + + pfn_user + pfn_free + pfn_hwpoison + pfn_offline; > shrinking = (pfn_original - pfn_excluded) * 100; > shrinking = shrinking / pfn_original; > total_size = info->page_size * pfn_original; > diff --git a/makedumpfile.h b/makedumpfile.h > index f02f86d..e3a2b29 100644 > --- a/makedumpfile.h > +++ b/makedumpfile.h > @@ -1927,6 +1927,7 @@ struct number_table { > long PG_hwpoison; > > long PAGE_BUDDY_MAPCOUNT_VALUE; > + long PAGE_OFFLINE_MAPCOUNT_VALUE; > long SECTION_SIZE_BITS; > long MAX_PHYSMEM_BITS; > long HUGETLB_PAGE_DTOR; > -- > 2.17.2 > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec