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authorJérôme Glisse <jglisse@redhat.com>2017-11-16 04:34:11 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-16 05:21:03 +0300
commit4645b9fe84bf4878f04c7959a75df7c3c2d1bbb9 (patch)
tree83fc19e23f907ea229fd8a99aedbbf967057eae4 /mm/memory.c
parent0f10851ea475e08896ee5d9a2036d1bb46a8f3a4 (diff)
downloadlinux-4645b9fe84bf4878f04c7959a75df7c3c2d1bbb9.tar.xz
mm/mmu_notifier: avoid call to invalidate_range() in range_end()
This is an optimization patch that only affect mmu_notifier users which rely on the invalidate_range() callback. This patch avoids calling that callback twice in a row from inside __mmu_notifier_invalidate_range_end Existing pattern (before this patch): mmu_notifier_invalidate_range_start() pte/pmd/pud_clear_flush_notify() mmu_notifier_invalidate_range() mmu_notifier_invalidate_range_end() mmu_notifier_invalidate_range() New pattern (after this patch): mmu_notifier_invalidate_range_start() pte/pmd/pud_clear_flush_notify() mmu_notifier_invalidate_range() mmu_notifier_invalidate_range_only_end() We call the invalidate_range callback after clearing the page table under the page table lock and we skip the call to invalidate_range inside the __mmu_notifier_invalidate_range_end() function. Idea from Andrea Arcangeli Link: http://lkml.kernel.org/r/20171017031003.7481-3-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alistair Popple <alistair@popple.id.au> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index a4518aedf4dd..42fb30300bb5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2554,7 +2554,11 @@ static int wp_page_copy(struct vm_fault *vmf)
put_page(new_page);
pte_unmap_unlock(vmf->pte, vmf->ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+ /*
+ * No need to double call mmu_notifier->invalidate_range() callback as
+ * the above ptep_clear_flush_notify() did already call it.
+ */
+ mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end);
if (old_page) {
/*
* Don't let another task, with possibly unlocked vma,