path: root/mm/internal.h
diff options
authorHugh Dickins <hugh@veritas.com>2009-01-06 14:40:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:59:07 -0800
commit22b31eec63e5f2e219a3ee15f456897272bc73e8 (patch)
tree906e4975a0e2cdef15ef071b4890e3b28e36cf39 /mm/internal.h
parent3dc147414ccad81dc33edb80774b1fed12a38c08 (diff)
badpage: vm_normal_page use print_bad_pte
print_bad_pte() is so far being called only when zap_pte_range() finds negative page_mapcount, or there's a fault on a pte_file where it does not belong. That's weak coverage when we suspect pagetable corruption. Originally, it was called when vm_normal_page() found an invalid pfn: but pfn_valid is expensive on some architectures and configurations, so 2.6.24 put that under CONFIG_DEBUG_VM (which doesn't help in the field), then 2.6.26 replaced it by a VM_BUG_ON (likewise). Reinstate the print_bad_pte() in vm_normal_page(), but use a cheaper test than pfn_valid(): memmap_init_zone() (used in bootup and hotplug) keep a __read_mostly note of the highest_memmap_pfn, vm_normal_page() then check pfn against that. We could call this pfn_plausible() or pfn_sane(), but I doubt we'll need it elsewhere: of course it's not reliable, but gives much stronger pagetable validation on many boxes. Also use print_bad_pte() when the pte_special bit is found outside a VM_PFNMAP or VM_MIXEDMAP area, instead of VM_BUG_ON. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/internal.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/internal.h b/mm/internal.h
index 13333bc2eb6..1981bc9454f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -49,6 +49,7 @@ extern void putback_lru_page(struct page *page);
* in mm/page_alloc.c
+extern unsigned long highest_memmap_pfn;
extern void __free_pages_bootmem(struct page *page, unsigned int order);