On kernels from v2.6.38 and later kernels, buddy page is marked by _mapcount == PAGE_BUDDY_MAPCOUNT_VALUE, which varies once as follows:
kernel version | PAGE_BUDDY_MAPCOUNT_VALUE ------------------+-------------------------- v2.6.38 | -2 v2.6.39 and later | -128 One more notice is that _mapcount shares its memory with other fields for SLAB/SLUB when PG_slab is set. Before looking up _mapcount value, we need to check if PG_slab is set. Since this page_is_buddy needs _mapcount, we use freelist logic if _mapcount is not available. Recall that PG_slab has been 7 since v2.6.15. No need to check it. Signed-off-by: HATAYAMA Daisuke <[email protected]> --- makedumpfile.c | 21 +++++++++++++++++++++ 1 files changed, 21 insertions(+), 0 deletions(-) diff --git a/makedumpfile.c b/makedumpfile.c index 0e44a8b..7b13dca 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -3668,12 +3668,33 @@ exclude_free_page(void) return TRUE; } +/* + * For v2.6.38 and later kernel versions. + */ +static int +page_is_buddy_v3(unsigned long flags, unsigned int _mapcount, + unsigned long private, unsigned int _count) +{ + if (flags & (1UL << NUMBER(PG_slab))) + return FALSE; + + if (_mapcount == (int)NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE)) + return TRUE; + + return FALSE; +} + static void setup_page_is_buddy(void) { if (OFFSET(page.private) == NOT_FOUND_STRUCTURE) goto out; + if (NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) != NOT_FOUND_NUMBER) { + if (OFFSET(page._mapcount) != NOT_FOUND_STRUCTURE) + info->page_is_buddy = page_is_buddy_v3; + } + out: if (!info->page_is_buddy) DEBUG_MSG("Can't select page_is_buddy handler; " _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
