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authorDavid Miller <davem@davemloft.net>2012-10-08 16:34:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:23:06 +0900
commitf5c8ad47284ca01dafc37da5a72bb9644174d387 (patch)
tree9d05ff565ad5e3b90933cacad012ad9724a8a83e /mm/huge_memory.c
parentb113da65785d5f3f9ff1451ec0fe43d6d76da25b (diff)
mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
Invalidation sequences are handled in various ways on various architectures. One way, which sparc64 uses, is to let the set_*_at() functions accumulate pending flushes into a per-cpu array. Then the flush_tlb_range() et al. calls process the pending TLB flushes. In this regime, the __tlb_remove_*tlb_entry() implementations are essentially NOPs. The canonical PTE zap in mm/memory.c is: ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr); With a subsequent tlb_flush_mmu() if needed. Mirror this in the THP PMD zapping using: orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); And we properly accomodate TLB flush mechanims like the one described above. Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 68a3c93036f..a863af26c79 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1024,9 +1024,10 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
if (__pmd_trans_huge_lock(pmd, vma) == 1) {
struct page *page;
pgtable_t pgtable;
+ pmd_t orig_pmd;
pgtable = pgtable_trans_huge_withdraw(tlb->mm);
- page = pmd_page(*pmd);
- pmd_clear(pmd);
+ orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
+ page = pmd_page(orig_pmd);
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
page_remove_rmap(page);
VM_BUG_ON(page_mapcount(page) < 0);