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ARM: make_coherent: fix problems with highpte, part 1

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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>
This commit is contained in:
Russell King 2009-12-18 16:24:34 +00:00
parent f8a85f1164
commit 56dd47098a
1 changed files with 11 additions and 2 deletions
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13
arch/arm/mm/fault-armv.c
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@ -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;
}