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

diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index 4a191c47286748c65cf2e7eb8753239af4c3b5d5..d27960c89a7131cac93b8549e6326ce3b6a9ea5e 100644 (file)
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -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_ */

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index db09234589409760b91cb9e696472a3e828476f9..8e4f41d9af4d47279e13a33edd317ce5de32e451 100644 (file)
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -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

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 65c98eb5483c24946321bbca51dd0ebc02da0a00..82166bf974e14262ecfb064ea7c173d006d3ab98 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -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: