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 converted tlb->need_flush = 1 to a VM_BUG_ON(!tlb->need_flush) in
__tlb_remove_page() as suggested by Andrea Arcangeli. __tlb_remove_page()
is supposed to be called after tlb_remove_xxx_tlb_entry() and we can catch
any misuse.
Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---
include/asm-generic/tlb.h | 14 ++++++++++++++
include/linux/huge_mm.h | 2 +-
mm/huge_memory.c | 3 ++-
mm/memory.c | 4 ++--
4 files changed, 19 insertions(+), 4 deletions(-)
Index: linux/include/asm-generic/tlb.h
===================================================================
--- linux.orig/include/asm-generic/tlb.h 2011-11-15 09:39:11.000000000 +0800
+++ linux/include/asm-generic/tlb.h 2011-11-15 09:39:23.000000000 +0800
@@ -139,6 +139,20 @@ static inline void tlb_remove_page(struc
__tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
+/**
+ * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation
+ * This is a nop so far, because only x86 needs it.
+ */
+#ifndef __tlb_remove_pmd_tlb_entry
+#define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0)
+#endif
+
+#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
+ do { \
+ tlb->need_flush = 1; \
+ __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
+ } while (0)
+
#define pte_free_tlb(tlb, ptep, address) \
do { \
tlb->need_flush = 1; \
Index: linux/include/linux/huge_mm.h
===================================================================
--- linux.orig/include/linux/huge_mm.h 2011-11-15 09:39:11.000000000 +0800
+++ linux/include/linux/huge_mm.h 2011-11-15 09:39:23.000000000 +0800
@@ -18,7 +18,7 @@ extern struct page *follow_trans_huge_pm
unsigned int flags);
extern int zap_huge_pmd(struct mmu_gather *tlb,
struct vm_area_struct *vma,
- pmd_t *pmd);
+ pmd_t *pmd, unsigned long addr);
extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
unsigned char *vec);
Index: linux/mm/huge_memory.c
===================================================================
--- linux.orig/mm/huge_memory.c 2011-11-15 09:39:17.000000000 +0800
+++ linux/mm/huge_memory.c 2011-11-15 09:39:23.000000000 +0800
@@ -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,
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);
Index: linux/mm/memory.c
===================================================================
--- linux.orig/mm/memory.c 2011-11-15 09:39:11.000000000 +0800
+++ linux/mm/memory.c 2011-11-15 09:40:55.000000000 +0800
@@ -293,7 +293,7 @@ int __tlb_remove_page(struct mmu_gather
{
struct mmu_gather_batch *batch;
- tlb->need_flush = 1;
+ VM_BUG_ON(!tlb->need_flush);
if (tlb_fast_mode(tlb)) {
free_page_and_swap_cache(page);
@@ -1231,7 +1231,7 @@ static inline unsigned long zap_pmd_rang
if (next-addr != HPAGE_PMD_SIZE) {
VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
split_huge_page_pmd(vma->vm_mm, pmd);
- } else if (zap_huge_pmd(tlb, vma, pmd))
+ } else if (zap_huge_pmd(tlb, vma, pmd, addr))
continue;
/* fall through */
}
--
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