The patch titled
Subject: mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
has been added to the -mm tree. Its filename is
mm-highmem-dont-treat-pkmap_addrlast_pkmap-as-a-highmem-address.patch
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------------------------------------------------------
From: Will Deacon <will.deacon@xxxxxxx>
Subject: mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
kmap_to_page returns the corresponding struct page for a virtual address
of an arbitrary mapping. This works by checking whether the address falls
in the pkmap region and using the pkmap page tables instead of the linear
mapping if appropriate.
Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is
incorrectly treated as a highmem address and we can end up walking off the
end of pkmap_page_table and subsequently passing junk to pte_page.
This patch fixes the bound check to stay within the pkmap tables.
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/highmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/highmem.c~mm-highmem-dont-treat-pkmap_addrlast_pkmap-as-a-highmem-address mm/highmem.c
--- a/mm/highmem.c~mm-highmem-dont-treat-pkmap_addrlast_pkmap-as-a-highmem-address
+++ a/mm/highmem.c
@@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr)
{
unsigned long addr = (unsigned long)vaddr;
- if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
+ if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
return pte_page(pkmap_page_table[i]);
}
_
Patches currently in -mm which might be from will.deacon@xxxxxxx are
mm-highmem-dont-treat-pkmap_addrlast_pkmap-as-a-highmem-address.patch
linux-next.patch
mm-thp-set-the-accessed-flag-for-old-pages-on-access-fault.patch
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