Commit d12de1ef authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 

Pull powerpc mremap fix from Ben Herrenschmidt:
 "This is the patch that I had sent after -rc8 and which we decided to
  wait before merging.  It's based on a different tree than my -next
  branch (it needs some pre-reqs that were in -rc4 or so while my -next
  is based on -rc1) so I left it as a separate branch for your to pull.
  It's identical to the request I did 2 or 3 weeks back.

  This fixes crashes in mremap with THP on powerpc.

  The fix however requires a small change in the generic code.  It moves
  a condition into a helper we can override from the arch which is
  harmless, but it *also* slightly changes the order of the set_pmd and
  the withdraw & deposit, which should be fine according to Kirill (who
  wrote that code) but I agree -rc8 is a bit late...

  It was acked by Kirill and Andrew told me to just merge it via powerpc"

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/thp: Fix crash on mremap
parents ba635f8c b3084f4d

arch/powerpc/include/asm/pgtable-ppc64.h

+14 −0
Original line number Diff line number Diff line
@@ -558,5 +558,19 @@ extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp); 
#define __HAVE_ARCH_PMDP_INVALIDATE

extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,

			    pmd_t *pmdp);



#define pmd_move_must_withdraw pmd_move_must_withdraw

typedef struct spinlock spinlock_t;

static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,

					 spinlock_t *old_pmd_ptl)

{

	/*

	 * Archs like ppc64 use pgtable to store per pmd

	 * specific information. So when we switch the pmd,

	 * we should also withdraw and deposit the pgtable

	 */

	return true;

}



#endif /* __ASSEMBLY__ */

#endif /* _ASM_POWERPC_PGTABLE_PPC64_H_ */

include/asm-generic/pgtable.h

+12 −0
Original line number Diff line number Diff line
@@ -558,6 +558,18 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp) 
}

#endif



#ifndef pmd_move_must_withdraw

static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,

					 spinlock_t *old_pmd_ptl)

{

	/*

	 * With split pmd lock we also need to move preallocated

	 * PTE page table if new_pmd is on different PMD page table.

	 */

	return new_pmd_ptl != old_pmd_ptl;

}

#endif



/*

 * This function is meant to be used by sites walking pagetables with

 * the mmap_sem hold in read mode to protect against MADV_DONTNEED and

mm/huge_memory.c

+5 −9
Original line number Diff line number Diff line
@@ -1508,19 +1508,15 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, 
			spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);

		pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);

		VM_BUG_ON(!pmd_none(*new_pmd));

		set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));

		if (new_ptl != old_ptl) {

			pgtable_t pgtable;



			/*

			 * Move preallocated PTE page table if new_pmd is on

			 * different PMD page table.

			 */

		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {

			pgtable_t pgtable;

			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);

			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);



			spin_unlock(new_ptl);

		}

		set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));

		if (new_ptl != old_ptl)

			spin_unlock(new_ptl);

		spin_unlock(old_ptl);

	}

out:

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