Add a kernel config and help document for CRASH_DUMP_BITMAP. Signed-off-by: Jingbai Ma <jingbai...@hp.com> --- Documentation/kdump/crash_dump_bitmap.txt | 378 +++++++++++++++++++++++++++++ arch/x86/Kconfig | 16 + 2 files changed, 394 insertions(+), 0 deletions(-) create mode 100644 Documentation/kdump/crash_dump_bitmap.txt
diff --git a/Documentation/kdump/crash_dump_bitmap.txt b/Documentation/kdump/crash_dump_bitmap.txt new file mode 100644 index 0000000..468cdf2 --- /dev/null +++ b/Documentation/kdump/crash_dump_bitmap.txt @@ -0,0 +1,378 @@ +================================================================ +Documentation for Crash Dump Bitmap +================================================================ + +This document includes overview, setup and installation, and analysis +information. + +Overview +======== + +Traditionally, to reduce the size of dump file, dumper scans all memory +pages to exclude the unnecessary memory pages after capture kernel +booted, and scan it in userspace code (makedumpfile). + +It introduces several problems: + +1. Requires more memory to store memory bitmap on systems with large +amount of memory installed. And in capture kernel there is only a few +free memory available, it will cause an out of memory error and fail. +(Non-cyclic mode) + +2. Scans all memory pages in makedumpfile is a very slow process. On +system with 1TB or more memory installed, the scanning process is very +long. Typically on 1TB idle system, it takes about 19 minutes. On system +with 4TB or more memory installed, it even doesn't work. To address the +out of memory issue on system with big memory (4TB or more memory +installed), makedumpfile v1.5.1 introduces a new cyclic mode. It only +scans a piece of memory pages each time, and do it cyclically to scan +all memory pages. But it runs more slowly, on 1TB system, takes about 33 +minutes. + +3. Scans memory pages code in makedumpfile is very complicated, without +kernel memory management related data structure, makedumpfile has to +build up its on data structure, and will not able to use some macros +that only be available in kernel (e.g. page_to_pfn), and has to use some +slow lookup algorithm instead. + +This patch introduces a new way to scan memory pages. It reserves a piece of +memory (1 bit for each page, 32MB per TB memory on x86 systems) in the first +kernel. During the kernel panic process, it scans all memory pages, clear the +bit for all excluded memory pages in the reserved memory. + +We have several benefits by this new approach: + +1. It's extremely fast, on 1TB system only takes about 17.5 seconds to +scan all memory pages! + +2. Reduces the memory requirement of makedumpfile by putting the +reserved memory in the first kernel memory space. + +3. Simplifies the complexity of existing memory pages scanning code in +userspace. + + +Usage +===== + +1) Enable "kernel crash dump bitmap" in "Processor type and features", under +"kernel crash dumps". + +CONFIG_CRASH_DUMP_BITMAP=y + +it depends on "kexec system call" and "kernel crash dumps", so there features +must be enabled also. + +CONFIG_KEXEC=y +CONFIG_CRASH_DUMP=y + +2) Enable "sysfs file system support" in "Filesystem" -> "Pseudo filesystems.". + + CONFIG_SYSFS=y + +3) Compile and install the new kernel. + +4) Check the new kernel. +Once new kernel has booted, there will be a new foler +/proc/crash_dump_bitmap. +Check current dump level: +cat /proc/crash_dump_bitmap/dump_level + +Set dump level: +echo "dump level" > /proc/crash_dump_bitmap/dump_level + +The dump level is as same as the parameter of makedumpfile -d dump_level. + +Run page scan and check page status: +cat /proc/crash_dump_bitmap/page_status + +5) Download makedumpfile v1.5.3 or later from sourceforge: +http://sourceforge.net/projects/makedumpfile/ + +6) Patch it with the patch at the end of this file. + +7) Compile it and copy the patched makedumpfile into the right folder +(/sbin or /usr/sbin) + +8) Change the /etc/kdump.conf, and a "-q" in the makedumpfile parameter +line. It will tell makedumpfile to use the crash dump bitmap in kernel. +core_collector makedumpfile --non-cyclic -q -c -d 31 --message-level 23 + +9) Regenerate initramfs to make sure the patched makedumpfile and config +has been included in it. + + +To Do +===== + +It only supports x86-64 architecture currently, need to add supports for +other architectures. + + +Contact +======= + +Jingbai Ma (jingbai...@hp.com) + + +Patch (for makedumpfile v1.5.3) + +Please forgive me, for some format issues of makedumpfile source, I have +to wrap this patch with '#'. Please use this sed command to get the +patch for makedumpfile: + +sed -n -e "s/^#\(.*\)#$/\1/p" crash_dump_bitmap.txt > makedumpfile.patch + +===== +#diff --git a/makedumpfile.c b/makedumpfile.c# +#index acb1b21..f29b6a5 100644# +#--- a/makedumpfile.c# +#+++ b/makedumpfile.c# +#@@ -34,6 +34,10 @@ struct srcfile_table srcfile_table;# +# struct vm_table vt = { 0 };# +# struct DumpInfo *info = NULL;# +# # +#+struct crash_dump_bitmap_info crash_dump_bitmap_info;# +#+# +#+const unsigned int CURRENT_BITMAP_INFO_VERSION = 1;# +#+# +# char filename_stdout[] = FILENAME_STDOUT;# +# # +# /*# +#@@ -892,6 +896,7 @@ get_symbol_info(void)# +# SYMBOL_INIT(node_remap_start_vaddr, "node_remap_start_vaddr");# +# SYMBOL_INIT(node_remap_end_vaddr, "node_remap_end_vaddr");# +# SYMBOL_INIT(node_remap_start_pfn, "node_remap_start_pfn");# +#+ SYMBOL_INIT(crash_dump_bitmap_info, "crash_dump_bitmap_info");# +# # +# if (SYMBOL(node_data) != NOT_FOUND_SYMBOL)# +# SYMBOL_ARRAY_TYPE_INIT(node_data, "node_data");# +#@@ -1704,6 +1709,8 @@ read_vmcoreinfo(void)# +# READ_SYMBOL("node_remap_end_vaddr", node_remap_end_vaddr);# +# READ_SYMBOL("node_remap_start_pfn", node_remap_start_pfn);# +# # +#+ READ_SYMBOL("crash_dump_bitmap_info", crash_dump_bitmap_info);# +#+# +# READ_STRUCTURE_SIZE("page", page);# +# READ_STRUCTURE_SIZE("mem_section", mem_section);# +# READ_STRUCTURE_SIZE("pglist_data", pglist_data);# +#@@ -4423,6 +4430,74 @@ copy_bitmap(void)# +# int# +# create_2nd_bitmap(void)# +# {# +#+ off_t offset_page;# +#+ char buf1[info->page_size], buf2[info->page_size];# +#+ int i;# +#+# +#+ if (info->flag_crash_dump_bitmap) {# +#+ offset_page = 0;# +#+ while (offset_page < (info->len_bitmap / 2)) {# +#+ if (lseek(info->bitmap1->fd, info->bitmap1->offset# +#+ + offset_page, SEEK_SET) < 0) {# +#+ ERRMSG("Can't seek the bitmap(%s). %s\n",# +#+ info->bitmap1->file_name, strerror(errno));# +#+ return FALSE;# +#+ }# +#+# +#+ if (read(info->bitmap1->fd, buf1, info->page_size)# +#+ != info->page_size) {# +#+ ERRMSG("Can't read bitmap(%s). %s\n",# +#+ info->bitmap1->file_name,# +#+ strerror(errno));# +#+ return FALSE;# +#+ }# +#+# +#+ if (readmem(PADDR, crash_dump_bitmap_info.bitmap# +#+ + offset_page, buf2, info->page_size)# +#+ != info->page_size) {# +#+ ERRMSG("Can't read bitmap1! addr=%llx\n",# +#+ crash_dump_bitmap_info.bitmap# +#+ + offset_page);# +#+ return FALSE;# +#+ }# +#+# +#+ if (crash_dump_bitmap_info.version# +#+ != CURRENT_BITMAP_INFO_VERSION) {# +#+ ERRMSG("bitmap version! expected=%d, got=%d\n",# +#+ CURRENT_BITMAP_INFO_VERSION,# +#+ crash_dump_bitmap_info.version);# +#+ return FALSE;# +#+ }# +#+# +#+ for (i = 0; i < info->page_size; i++)# +#+ buf2[i] = buf1[i] & buf2[i];# +#+# +#+ if (lseek(info->bitmap2->fd, info->bitmap2->offset# +#+ + offset_page, SEEK_SET) < 0) {# +#+ ERRMSG("Can't seek the bitmap(%s). %s\n",# +#+ info->bitmap2->file_name, strerror(errno));# +#+ return FALSE;# +#+ }# +#+# +#+ if (write(info->bitmap2->fd, buf2, info->page_size)# +#+ != info->page_size) {# +#+ ERRMSG("Can't write the bitmap(%s). %s\n",# +#+ info->bitmap2->file_name, strerror(errno));# +#+ return FALSE;# +#+ }# +#+# +#+ offset_page += info->page_size;# +#+ }# +#+# +#+ pfn_cache = crash_dump_bitmap_info.cache_pages;# +#+ pfn_cache_private = crash_dump_bitmap_info.cache_private_pages;# +#+ pfn_user = crash_dump_bitmap_info.user_pages;# +#+ pfn_free = crash_dump_bitmap_info.free_pages;# +#+ pfn_hwpoison = crash_dump_bitmap_info.hwpoison_pages;# +#+# +#+ return TRUE;# +#+ }# +#+# +# /*# +# * Copy 1st-bitmap to 2nd-bitmap.# +# */# +#@@ -4587,6 +4662,46 @@ create_dump_bitmap(void)# +# if (!prepare_bitmap_buffer())# +# goto out;# +# # +#+ if (info->flag_crash_dump_bitmap# +#+ && (SYMBOL(crash_dump_bitmap_info)# +#+ != NOT_FOUND_SYMBOL)) {# +#+ /* Read crash_dump_bitmap_info from old kernel */# +#+ readmem(VADDR, SYMBOL(crash_dump_bitmap_info),# +#+ &crash_dump_bitmap_info,# +#+ sizeof(struct crash_dump_bitmap_info));# +#+# +#+ if (!crash_dump_bitmap_info.bitmap_size# +#+ || !crash_dump_bitmap_info.bitmap) {# +#+ ERRMSG("Can't get crash_dump bitmap info! ");# +#+ ERRMSG("Failback to legacy mode.\n");# +#+ ERRMSG("crash_dump_bitmap_info=0x%llx, ",# +#+ SYMBOL(crash_dump_bitmap_info));# +#+ ERRMSG("bitmap=0x%llx, ",# +#+ crash_dump_bitmap_info.bitmap);# +#+ ERRMSG("bitmap_size=%lld\n",# +#+ crash_dump_bitmap_info.bitmap_size);# +#+# +#+ info->flag_crash_dump_bitmap = FALSE;# +#+ } else {# +#+ MSG("crash_dump_bitmap: ");# +#+ MSG("crash_dump_bitmap_info=0x%llx, ",# +#+ SYMBOL(crash_dump_bitmap_info));# +#+ MSG("bitmap=0x%llx, ",# +#+ crash_dump_bitmap_info.bitmap);# +#+ MSG("bitmap_size=%lld, ",# +#+ crash_dump_bitmap_info.bitmap_size);# +#+ MSG("cache_pages=0x%lx, ",# +#+ crash_dump_bitmap_info.cache_pages);# +#+ MSG("cache_private_pages=0x%lx, ",# +#+ crash_dump_bitmap_info# +#+ .cache_private_pages);# +#+ MSG("user_pages=0x%lx, ",# +#+ crash_dump_bitmap_info.user_pages);# +#+ MSG("free_pages=0x%lx\n",# +#+ crash_dump_bitmap_info.free_pages);# +#+ }# +#+ }# +#+# +# if (!create_1st_bitmap())# +# goto out;# +# # +#@@ -8454,7 +8569,8 @@ main(int argc, char *argv[])# +# # +# info->block_order = DEFAULT_ORDER;# +# message_level = DEFAULT_MSG_LEVEL;# +#- while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lMpRrsvXx:", longopts,# +#+ while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lMpqRrsvXx:",# +#+ longopts,# +# NULL)) != -1) {# +# switch (opt) {# +# case 'b':# +#@@ -8518,6 +8634,10 @@ main(int argc, char *argv[])# +# case 'P':# +# info->xen_phys_start = strtoul(optarg, NULL, 0);# +# break;# +#+ case 'q':# +#+ info->flag_crash_dump_bitmap = TRUE;# +#+ info->flag_cyclic = FALSE;# +#+ break;# +# case 'R':# +# info->flag_rearrange = 1;# +# break;# +#diff --git a/makedumpfile.h b/makedumpfile.h# +#index 272273e..6404b16 100644# +#--- a/makedumpfile.h# +#+++ b/makedumpfile.h# +#@@ -41,6 +41,8 @@# +# #include "dwarf_info.h"# +# #include "diskdump_mod.h"# +# #include "sadump_mod.h"# +#+#include "print_info.h"# +#+# +# # +# /*# +# * Result of command# +#@@ -889,6 +891,7 @@ struct DumpInfo {# +# int flag_refiltering; /* refilter from kdump-compressed file */# +# int flag_force; /* overwrite existing stuff */# +# int flag_exclude_xen_dom;/* exclude Domain-U from xen-kdump */# +#+ int flag_crash_dump_bitmap;/* crash dump bitmap */# +# int flag_dmesg; /* dump the dmesg log out of the vmcore file */# +# int flag_nospace; /* the flag of "No space on device" error */# +# unsigned long vaddr_for_vtop; /* virtual address for debugging */# +#@@ -1153,6 +1156,11 @@ struct symbol_table {# +# unsigned long long __per_cpu_load;# +# unsigned long long cpu_online_mask;# +# unsigned long long kexec_crash_image;# +#+# +#+ /*# +#+ * for crash_dump_bitmap# +#+ */# +#+ unsigned long long crash_dump_bitmap_info;# +# };# +# # +# struct size_table {# +#@@ -1381,6 +1389,20 @@ struct srcfile_table {# +# char pud_t[LEN_SRCFILE];# +# };# +# # +#+/*# +#+ * for crash_dump_bitmap# +#+ */# +#+struct crash_dump_bitmap_info {# +#+ unsigned int version;# +#+ unsigned long long bitmap;# +#+ unsigned long long bitmap_size;# +#+ unsigned long cache_pages;# +#+ unsigned long cache_private_pages;# +#+ unsigned long user_pages;# +#+ unsigned long free_pages;# +#+ unsigned long hwpoison_pages;# +#+};# +#+# +# extern struct symbol_table symbol_table;# +# extern struct size_table size_table;# +# extern struct offset_table offset_table;# +#@@ -1541,8 +1563,20 @@ is_dumpable(struct dump_bitmap *bitmap, unsigned long long pfn)# +# off_t offset;# +# if (pfn == 0 || bitmap->no_block != pfn/PFN_BUFBITMAP) {# +# offset = bitmap->offset + BUFSIZE_BITMAP*(pfn/PFN_BUFBITMAP);# +#- lseek(bitmap->fd, offset, SEEK_SET);# +#- read(bitmap->fd, bitmap->buf, BUFSIZE_BITMAP);# +#+ if (lseek(bitmap->fd, offset, SEEK_SET) < 0) {# +#+ ERRMSG("Can't seek bitmap file %s:(%d), ",# +#+ bitmap->file_name, bitmap->fd);# +#+ ERRMSG("offset=%ld, error: %s\n",# +#+ offset, strerror(errno));# +#+ }# +#+# +#+ if (read(bitmap->fd, bitmap->buf, BUFSIZE_BITMAP) < 0) {# +#+ ERRMSG("Can't read bitmap file %s:(%d), ",# +#+ bitmap->file_name, bitmap->fd);# +#+ ERRMSG("offset=%ld, error: %s\n",# +#+ offset, strerror(errno));# +#+ }# +#+# +# if (pfn == 0)# +# bitmap->no_block = 0;# +# else# diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a4f24f5..7b6232e 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1633,6 +1633,22 @@ config CRASH_DUMP (CONFIG_RELOCATABLE=y). For more details see Documentation/kdump/kdump.txt +config CRASH_DUMP_BITMAP + bool "kernel crash dump bitmap" + def_bool y + depends on CRASH_DUMP && X86_64 + ---help--- + This option will enable the kernel crash dump bitmap support. + It will reserve a block of memory to store crash dump bitmap. + (1 bit for each page, 32MB per TB memory on x86 systems) + It will scan all memory pages during crash processing and mark the + excluded memory page bit in the reserved memory. It will be very + fast compare to scan it later in the capture kernel. + User can control which type of page to be excluded through procfs: + /proc/crash_dump_bitmap/dump_level + The default dump level is 31 (exclude all unnecessary pages). + For more details see Documentation/kdump/crash_dump_bitmap.txt + config KEXEC_JUMP bool "kexec jump" depends on KEXEC && HIBERNATION -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
