Commit-ID: 5e4bf1a55da976a5ed60901bb8801f1024ef9774 Gitweb: http://git.kernel.org/tip/5e4bf1a55da976a5ed60901bb8801f1024ef9774 Author: Ingo Molnar <mi...@kernel.org> AuthorDate: Tue, 20 Nov 2012 13:02:51 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 22 Nov 2012 21:52:06 +0100
x86/mm: Don't flush the TLB on #WP pmd fixups If we have a write protection #PF and fix up the pmd then the hugetlb code [the only user of pmdp_set_access_flags], in its do_huge_pmd_wp_page() page fault resolution function calls pmdp_set_access_flags() to mark the pmd permissive again, and flushes the TLB. This TLB flush is unnecessary: a flush on #PF is guaranteed on most (all?) x86 CPUs, and even in the worst-case we'll generate a spurious fault. So remove it. Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Paul Turner <p...@google.com> Cc: Lee Schermerhorn <lee.schermerh...@hp.com> Cc: Andrea Arcangeli <aarca...@redhat.com> Cc: Rik van Riel <r...@redhat.com> Cc: Johannes Weiner <han...@cmpxchg.org> Cc: Christoph Lameter <c...@linux.com> Cc: Mel Gorman <mgor...@suse.de> Cc: Hugh Dickins <hu...@google.com> Link: http://lkml.kernel.org/r/20121120120251.ga15...@gmail.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/mm/pgtable.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 8573b83..8a828d7 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -328,7 +328,12 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, if (changed && dirty) { *pmdp = entry; pmd_update_defer(vma->vm_mm, address, pmdp); - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + /* + * We had a write-protection fault here and changed the pmd + * to to more permissive. No need to flush the TLB for that, + * #PF is architecturally guaranteed to do that and in the + * worst-case we'll generate a spurious fault. + */ } return changed; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
