From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by kanga.kvack.org (Postfix) with ESMTP id 52B3B6B1A29 for ; Mon, 19 Nov 2018 05:18:41 -0500 (EST) Received: by mail-qk1-f200.google.com with SMTP id a199so67600789qkb.23 for ; Mon, 19 Nov 2018 02:18:41 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id c19si40699qkh.43.2018.11.19.02.18.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Nov 2018 02:18:39 -0800 (PST) From: David Hildenbrand Subject: [PATCH v1] makedumpfile: exclude pages that are logically offline Date: Mon, 19 Nov 2018 11:18:35 +0100 Message-Id: <20181119101835.9140-1-david@redhat.com> In-Reply-To: <20181119101616.8901-1-david@redhat.com> References: <20181119101616.8901-1-david@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devel@linuxdriverproject.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org, kexec-ml , pv-drivers@vmware.com, Kazuhito Hagio , David Hildenbrand 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 --- makedumpfile.c | 34 ++++++++++++++++++++++++++++++---- makedumpfile.h | 1 + 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/makedumpfile.c b/makedumpfile.c index 8923538..b8bfd4c 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_BUDDY_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