BugLink: http://bugs.launchpad.net/bugs/1607404
commit
56530f5d2ddc9b9fade7ef8db9cb886e9dc689b5 upstream.
Currently pmd_mknotpresent will use a zero entry to respresent an
invalidated pmd.
Unfortunately this definition clashes with pmd_none, thus it is
possible for a race condition to occur if zap_pmd_range sees pmd_none
whilst __split_huge_pmd_locked is running too with pmdp_invalidate
just called.
This patch fixes the race condition by modifying pmd_mknotpresent to
create non-zero faulting entries (as is done in other architectures),
removing the ambiguity with pmd_none.
[catalin.marinas@arm.com: using L_PMD_SECT_VALID instead of PMD_TYPE_SECT]
Fixes: 8d9625070073 ("ARM: mm: Transparent huge page support for LPAE systems.")
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
#define pfn_pmd(pfn,prot) (__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot)
-/* represent a notpresent pmd by zero, this is used by pmdp_invalidate */
+/* represent a notpresent pmd by faulting entry, this is used by pmdp_invalidate */
static inline pmd_t pmd_mknotpresent(pmd_t pmd)
{
- return __pmd(0);
+ return __pmd(pmd_val(pmd) & ~L_PMD_SECT_VALID);
}
static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)