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| author |   Jérôme Glisse <jglisse@redhat.com> | 2017-11-15 17:34:11 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-15 18:21:03 -0800 |
| commit | 4645b9fe84bf4878f04c7959a75df7c3c2d1bbb9 (patch) | |
| tree | 83fc19e23f907ea229fd8a99aedbbf967057eae4 /mm/mmu_notifier.c | |
| parent | mm/mmu_notifier: avoid double notification when it is useless (diff) | |
| download | linux-dev-4645b9fe84bf4878f04c7959a75df7c3c2d1bbb9.tar.xz linux-dev-4645b9fe84bf4878f04c7959a75df7c3c2d1bbb9.zip | |
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 '')
| -rw-r--r-- | mm/mmu_notifier.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 314285284e6e..96edb33fd09a 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -190,7 +190,9 @@ void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range_start); void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, - unsigned long start, unsigned long end) + unsigned long start, + unsigned long end, + bool only_end) { struct mmu_notifier *mn; int id; @@ -204,8 +206,13 @@ void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, * subsystem registers either invalidate_range_start()/end() or * invalidate_range(), so this will be no additional overhead * (besides the pointer check). + * + * We skip call to invalidate_range() if we know it is safe ie + * call site use mmu_notifier_invalidate_range_only_end() which + * is safe to do when we know that a call to invalidate_range() + * already happen under page table lock. */ - if (mn->ops->invalidate_range) + if (!only_end && mn->ops->invalidate_range) mn->ops->invalidate_range(mn, mm, start, end); if (mn->ops->invalidate_range_end) mn->ops->invalidate_range_end(mn, mm, start, end); |