Commit 9386fac3 authored Jul 06, 2017 by Punit Agrawal Committed by Linus Torvalds Jul 06, 2017

mm/hugetlb: allow architectures to override huge_pte_clear()

When unmapping a hugepage range, huge_pte_clear() is used to clear the
page table entries that are marked as not present.  huge_pte_clear()
internally just ends up calling pte_clear() which does not correctly
deal with hugepages consisting of contiguous page table entries.

Add a size argument to address this issue and allow architectures to
override huge_pte_clear() by wrapping it in a #ifndef block.

Update s390 implementation with the size parameter as well.

Note that the change only affects huge_pte_clear() - the other generic
hugetlb functions don't need any change.

Link: http://lkml.kernel.org/r/20170522162555.4313-1-punit.agrawal@arm.com


Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>	[s390 bits]
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7868a208

arch/s390/include/asm/hugetlb.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -39,7 +39,7 @@ static inline int prepare_hugepage_range(struct file *file,
		#define arch_clear_hugepage_flags(page) do { } while (0)

		static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
		pte_t *ptep)
		pte_t *ptep, unsigned long sz)
		{
		if ((pte_val(*ptep) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
		pte_val(*ptep) = _REGION3_ENTRY_EMPTY;

include/asm-generic/hugetlb.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -31,10 +31,12 @@ static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
		return pte_modify(pte, newprot);
		}

		#ifndef huge_pte_clear
		static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
		pte_t *ptep)
		pte_t *ptep, unsigned long sz)
		{
		pte_clear(mm, addr, ptep);
		}
		#endif

		#endif /* _ASM_GENERIC_HUGETLB_H */

mm/hugetlb.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -3351,7 +3351,7 @@ void __unmap_hugepage_range(struct mmu_gather tlb, struct vm_area_struct vma,
		* unmapped and its refcount is dropped, so just clear pte here.
		*/
		if (unlikely(!pte_present(pte))) {
		huge_pte_clear(mm, address, ptep);
		huge_pte_clear(mm, address, ptep, sz);
		spin_unlock(ptl);
		continue;
		}

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