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authorRussell King <rmk+kernel@arm.linux.org.uk>2009-12-18 16:24:34 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-01-20 13:48:30 +0000
commit56dd47098abe1fdde598a8d8b7c04d775506f456 (patch)
tree5eda8a531087c9c068702aa426db8479a77147f8 /arch/arm
parentf8a85f1164a33e3eb5b421b137ced793ed53ee33 (diff)
ARM: make_coherent: fix problems with highpte, part 1
update_mmu_cache() is called with a page table already mapped. We call make_coherent(), which then calls adjust_pte() which wants to map other page tables. This causes kmap_atomic() to BUG() because the slot its trying to use is already taken. Since do_adjust_pte() modifies the page tables, we are also missing any form of locking, so we're risking corrupting the page tables. Fix this by using pte_offset_map_nested(), and taking the pte page table lock around do_adjust_pte(). Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/fault-armv.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 7a8efe1b37d..8e9bc517132 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -67,6 +67,7 @@ static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
{
+ spinlock_t *ptl;
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
@@ -80,11 +81,19 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
if (pmd_none_or_clear_bad(pmd))
return 0;
- pte = pte_offset_map(pmd, address);
+ /*
+ * This is called while another page table is mapped, so we
+ * must use the nested version. This also means we need to
+ * open-code the spin-locking.
+ */
+ ptl = pte_lockptr(vma->vm_mm, pmd);
+ pte = pte_offset_map_nested(pmd, address);
+ spin_lock(ptl);
ret = do_adjust_pte(vma, address, pte);
- pte_unmap(pte);
+ spin_unlock(ptl);
+ pte_unmap_nested(pte);
return ret;
}