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

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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
This commit is contained in:
Linus Torvalds 2014-01-27 21:03:39 -08:00
commit d12de1ef5e
3 changed files with 31 additions and 9 deletions
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14
arch/powerpc/include/asm/pgtable-ppc64.h
View file

@ -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_ */

12
include/asm-generic/pgtable.h
View file

@ -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

14
mm/huge_memory.c
View file

@ -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: