diff options
author | Ingo Molnar <mingo@kernel.org> | 2012-11-20 13:02:51 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2012-11-22 21:52:06 +0100 |
commit | 5e4bf1a55da976a5ed60901bb8801f1024ef9774 (patch) | |
tree | 346592b44148c59b4c7287877295df36ae402680 /arch/x86/mm/pgtable.c | |
parent | bbee3aec3472fc2ca10b6b1020aec84567ea25ce (diff) | |
download | linux-5e4bf1a55da976a5ed60901bb8801f1024ef9774.tar.bz2 |
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 <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20121120120251.GA15742@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm/pgtable.c')
-rw-r--r-- | arch/x86/mm/pgtable.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 8573b83a63d0..8a828d773e58 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; |