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-rw-r--r--include/asm-x86/pgalloc_32.h7
-rw-r--r--include/asm-x86/pgtable-3level.h21
2 files changed, 22 insertions, 6 deletions
diff --git a/include/asm-x86/pgalloc_32.h b/include/asm-x86/pgalloc_32.h
index 0caa37a9a25f..10c2b452e64c 100644
--- a/include/asm-x86/pgalloc_32.h
+++ b/include/asm-x86/pgalloc_32.h
@@ -74,6 +74,13 @@ static inline void pmd_free(pmd_t *pmd)
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
{
+ /* This is called just after the pmd has been detached from
+ the pgd, which requires a full tlb flush to be recognized
+ by the CPU. Rather than incurring multiple tlb flushes
+ while the address space is being pulled down, make the tlb
+ gathering machinery do a full flush when we're done. */
+ tlb->fullmm = 1;
+
paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
tlb_remove_page(tlb, virt_to_page(pmd));
}
diff --git a/include/asm-x86/pgtable-3level.h b/include/asm-x86/pgtable-3level.h
index ed4c6f0e57ec..a195c3e757b9 100644
--- a/include/asm-x86/pgtable-3level.h
+++ b/include/asm-x86/pgtable-3level.h
@@ -96,14 +96,23 @@ static inline void pud_clear(pud_t *pudp)
set_pud(pudp, __pud(0));
/*
- * Pentium-II erratum A13: in PAE mode we explicitly have to flush
- * the TLB via cr3 if the top-level pgd is changed...
+ * In principle we need to do a cr3 reload here to make sure
+ * the processor recognizes the changed pgd. In practice, all
+ * the places where pud_clear() gets called are followed by
+ * full tlb flushes anyway, so we can defer the cost here.
*
- * XXX I don't think we need to worry about this here, since
- * when clearing the pud, the calling code needs to flush the
- * tlb anyway. But do it now for safety's sake. - jsgf
+ * Specifically:
+ *
+ * mm/memory.c:free_pmd_range() - immediately after the
+ * pud_clear() it does a pmd_free_tlb(). We change the
+ * mmu_gather structure to do a full tlb flush (which has the
+ * effect of reloading cr3) when the pagetable free is
+ * complete.
+ *
+ * arch/x86/mm/hugetlbpage.c:huge_pmd_unshare() - the call to
+ * this is followed by a flush_tlb_range, which on x86 does a
+ * full tlb flush.
*/
- write_cr3(read_cr3());
}
#define pud_page(pud) \