thp: add tlb_remove_pmd_tlb_entry

We have tlb_remove_tlb_entry to indicate a pte tlb flush entry should be
flushed, but not a corresponding API for pmd entry.  This isn't a
problem so far because THP is only for x86 currently and tlb_flush()
under x86 will flush entire TLB.  But this is confusion and could be
missed if thp is ported to other arch.

Also convert tlb->need_flush = 1 to a VM_BUG_ON(!tlb->need_flush) in
__tlb_remove_page() as suggested by Andrea Arcangeli.  The
__tlb_remove_page() function is supposed to be called after
tlb_remove_xxx_tlb_entry() and we can catch any misuse.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 964fc5a2edd2..5a595554bd8c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1026,7 +1026,7 @@ out:
 }
 
 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
-                 pmd_t *pmd)
+                 pmd_t *pmd, unsigned long addr)
 {
         int ret = 0;
 
@@ -1042,6 +1042,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                         pgtable = get_pmd_huge_pte(tlb->mm);
                         page = pmd_page(*pmd);
                         pmd_clear(pmd);
+                        tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
                         page_remove_rmap(page);
                         VM_BUG_ON(page_mapcount(page) < 0);
                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);