Re: [Crash-utility] [PATCH 1/1 V4] crash: initial note of excluded page structures

Version 4 - Makes the warning: WARNING: The vmemmap page structures that are associated with the memory pages excluded by the "makedumpfile -d <level>" option have been excluded from this dump. The administrator has used "makedumpfile -e". This will cause failures in any command that accesses a page structure of a page that is not included in the dump. This is particularly likely when using several options of the kmem command. Version 3 - Changes the warning to be more complete: WARNING: All unused vmemmap page structures are excluded from this dump. This will cause failures of the kmem command if it attempts to walk any list of free pages (with options such as -f -F -i -s and -S) or interpret an address with kmem <address>, and incorrect output from kmem -p. Version 2 - Moves the warning to this point: ... This GDB was configured as "x86_64-unknown-linux-gnu"... WARNING: All unused vmemmap page structures are excluded from this dump. This will cause failures of the kmem command if it attempts to walk any list of free pages (with options -f -F -i -s and -S). SYSTEM MAP: /boot/System.map-2.6.32-cpw ... - Drop patch 2, which added warnings to individual kmem options. - Feel free to change the wording of the warning. And this patch is contingent upon the acceptance of a change to the makedumpfile command. http://marc.info/?l=kexec&m=138853299130125&w=2 If makedumpfile excludes unused page structures it will flag that fact in the dump header. (There are about 3.67 million pages full of page structures for every tera byte of system memory. The great bulk of those page structures are not needed.) Their exclusion is a makedumpfile option. Crash will display a note during initialization if such structures have been excluded. Crash commands that walk page freelists, for example, will fail. So the note will help the user understand why. Signed-off-by: Cliff Wickman <cpw(a)sgi.com&gt; --- defs.h | 1 + diskdump.c | 3 +++ diskdump.h | 1 + main.c | 11 +++++++++++ 4 files changed, 16 insertions(+) Index: crash-7.0.4/diskdump.c =================================================================== --- crash-7.0.4.orig/diskdump.c +++ crash-7.0.4/diskdump.c @@ -749,6 +749,9 @@ restart: dd->valid_pages[i]++; } + if (header->status & DUMP_DH_EXCLUDED_VMEMMAP) + pc->flags2 |= VMEXCLUDED; + return TRUE; err: Index: crash-7.0.4/diskdump.h =================================================================== --- crash-7.0.4.orig/diskdump.h +++ crash-7.0.4/diskdump.h @@ -84,6 +84,7 @@ struct kdump_sub_header { #define DUMP_DH_COMPRESSED_ZLIB 0x1 /* page is compressed with zlib */ #define DUMP_DH_COMPRESSED_LZO 0x2 /* page is compressed with lzo */ #define DUMP_DH_COMPRESSED_SNAPPY 0x4 /* page is compressed with snappy */ +#define DUMP_DH_EXCLUDED_VMEMMAP 0x8 /* unused vmemmap pages are excluded */ /* descriptor of each page for vmcore */ typedef struct page_desc { Index: crash-7.0.4/defs.h =================================================================== --- crash-7.0.4.orig/defs.h +++ crash-7.0.4/defs.h @@ -505,6 +505,7 @@ struct program_context { #define VMCOREINFO (0x400ULL) #define ALLOW_FP (0x800ULL) #define REM_PAUSED_F (0x1000ULL) +#define VMEXCLUDED (0x2000ULL) #define REMOTE_PAUSED() (pc->flags2 & REM_PAUSED_F) char *cleanup; char *namelist_orig; Index: crash-7.0.4/main.c =================================================================== --- crash-7.0.4.orig/main.c +++ crash-7.0.4/main.c @@ -662,6 +662,17 @@ main_loop(void) } else SIGACTION(SIGINT, restart, &pc->sigaction, NULL); + if (pc->flags2 & VMEXCLUDED) + fprintf(fp, + "WARNING: The vmemmap page structures that are associated with the\n" + " memory pages excluded by the \"makedumpfile -d <level>\"\n" + " option have been excluded from this dump.\n" + " The administrator has used \"makedumpfile -e\".\n" + " This will cause failures in any command that accesses a page\n" + " structure of a page that is not included in the dump. This\n" + " is particularly likely when using several options of the\n" + " kmem command.\n\n"); + /* * Display system statistics and current context. */