diff options
| author | Hugh Dickins <hugh@veritas.com> | 2009-01-06 14:40:09 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-06 15:59:07 -0800 |
| commit | 22b31eec63e5f2e219a3ee15f456897272bc73e8 (patch) | |
| tree | 906e4975a0e2cdef15ef071b4890e3b28e36cf39 /mm/internal.h | |
| parent | 3dc147414ccad81dc33edb80774b1fed12a38c08 (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')
| -rw-r--r-- | mm/internal.h | 1 |
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); /* |