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authorRik van Riel <riel@redhat.com>2012-11-06 09:54:47 +0000
committerMel Gorman <mgorman@suse.de>2012-12-11 14:28:33 +0000
commit0f9a921cf9bf3b524feddc484e2b4d070b7ca0d0 (patch)
tree4cad5a73d90a09863cb7615685f93e59192f256f /arch/x86
parentf4a75d2eb7b1e2206094b901be09adb31ba63681 (diff)
x86: mm: only do a local tlb flush in ptep_set_access_flags()
The function ptep_set_access_flags() is only ever invoked to set access flags or add write permission on a PTE. The write bit is only ever set together with the dirty bit. Because we only ever upgrade a PTE, it is safe to skip flushing entries on remote TLBs. The worst that can happen is a spurious page fault on other CPUs, which would flush that TLB entry. Lazily letting another CPU incur a spurious page fault occasionally is (much!) cheaper than aggressively flushing everybody else's TLB. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Michel Lespinasse <walken@google.com> Cc: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/mm/pgtable.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 8573b83a63d0..be3bb4690887 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -301,6 +301,13 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd)
free_page((unsigned long)pgd);
}
+/*
+ * Used to set accessed or dirty bits in the page table entries
+ * on other architectures. On x86, the accessed and dirty bits
+ * are tracked by hardware. However, do_wp_page calls this function
+ * to also make the pte writeable at the same time the dirty bit is
+ * set. In that case we do actually need to write the PTE.
+ */
int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty)
@@ -310,7 +317,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
if (changed && dirty) {
*ptep = entry;
pte_update_defer(vma->vm_mm, address, ptep);
- flush_tlb_page(vma, address);
+ __flush_tlb_one(address);
}
return changed;