The patch titled
Subject: mm/mmu_notifier: helper to test if a range invalidation is blockable
has been added to the -mm tree. Its filename is
mm-mmu_notifier-helper-to-test-if-a-range-invalidation-is-blockable.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mmu_notifier-helper-to-test-if-a-range-invalidation-is-blockable.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mmu_notifier-helper-to-test-if-a-range-invalidation-is-blockable.patch
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From: Jérôme Glisse <jglisse@xxxxxxxxxx>
Subject: mm/mmu_notifier: helper to test if a range invalidation is blockable
Patch series "mmu notifier provide context informations", v6.
Here I am not posting users of this, they already have been posted to
appropriate mailing list [6] and will be merge through the appropriate
tree once this patchset is upstream.
Note that this serie does not change any behavior for any existing code.
It just pass down more information to mmu notifier listener.
The rationale for this patchset:
CPU page table update can happens for many reasons, not only as a result
of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as
a result of kernel activities (memory compression, reclaim, migration,
...).
This patchset introduce a set of enums that can be associated with each of
the events triggering a mmu notifier:
- UNMAP: munmap() or mremap()
- CLEAR: page table is cleared (migration, compaction, reclaim, ...)
- PROTECTION_VMA: change in access protections for the range
- PROTECTION_PAGE: change in access protections for page in the range
- SOFT_DIRTY: soft dirtyness tracking
Being able to identify munmap() and mremap() from other reasons why the
page table is cleared is important to allow user of mmu notifier to update
their own internal tracking structure accordingly (on munmap or mremap it
is not longer needed to track range of virtual address as it becomes
invalid). Without this serie, driver are force to assume that every
notification is an munmap which triggers useless trashing within drivers
that associate structure with range of virtual address. Each driver is
force to free up its tracking structure and then restore it on next device
page fault. With this series we can also optimize device page table update. Patches to use this are at
https://lkml.org/lkml/2019/1/23/833
https://lkml.org/lkml/2019/1/23/834
https://lkml.org/lkml/2019/1/23/832
https://lkml.org/lkml/2019/1/23/831
Moreover this can also be used to optimize out some page table updates
such as for KVM where we can update the secondary MMU directly from the
callback instead of clearing it.
ACKS AMD/RADEON https://lkml.org/lkml/2019/2/1/395
ACKS RDMA https://lkml.org/lkml/2018/12/6/1473
This patch (of 8):
Simple helpers to test if range invalidation is blockable. Latter patches
use cocinnelle to convert all direct dereference of range-> blockable to
use this function instead so that we can convert the blockable field to an
unsigned for more flags.
Link: http://lkml.kernel.org/r/20190326164747.24405-2-jglisse@xxxxxxxxxx
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krcmar <rkrcmar@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmu_notifier.h | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/include/linux/mmu_notifier.h~mm-mmu_notifier-helper-to-test-if-a-range-invalidation-is-blockable
+++ a/include/linux/mmu_notifier.h
@@ -226,6 +226,12 @@ extern void __mmu_notifier_invalidate_ra
extern void __mmu_notifier_invalidate_range(struct mm_struct *mm,
unsigned long start, unsigned long end);
+static inline bool
+mmu_notifier_range_blockable(const struct mmu_notifier_range *range)
+{
+ return range->blockable;
+}
+
static inline void mmu_notifier_release(struct mm_struct *mm)
{
if (mm_has_notifiers(mm))
@@ -455,6 +461,11 @@ static inline void _mmu_notifier_range_i
#define mmu_notifier_range_init(range, mm, start, end) \
_mmu_notifier_range_init(range, start, end)
+static inline bool
+mmu_notifier_range_blockable(const struct mmu_notifier_range *range)
+{
+ return true;
+}
static inline int mm_has_notifiers(struct mm_struct *mm)
{
_
Patches currently in -mm which might be from jglisse@xxxxxxxxxx are
mm-hmm-select-mmu-notifier-when-selecting-hmm-v2.patch
mm-hmm-use-reference-counting-for-hmm-struct-v3.patch
mm-hmm-do-not-erase-snapshot-when-a-range-is-invalidated.patch
mm-hmm-improve-and-rename-hmm_vma_get_pfns-to-hmm_range_snapshot-v2.patch
mm-hmm-improve-and-rename-hmm_vma_fault-to-hmm_range_fault-v3.patch
mm-hmm-improve-driver-api-to-work-and-wait-over-a-range-v3.patch
mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays-v2.patch
mm-hmm-mirror-hugetlbfs-snapshoting-faulting-and-dma-mapping-v3.patch
mm-hmm-allow-to-mirror-vma-of-a-file-on-a-dax-backed-filesystem-v3.patch
mm-hmm-add-helpers-to-test-if-mm-is-still-alive-or-not.patch
mm-hmm-add-an-helper-function-that-fault-pages-and-map-them-to-a-device-v3.patch
mm-hmm-add-an-helper-function-that-fault-pages-and-map-them-to-a-device-v3-fix.patch
mm-hmm-convert-various-hmm_pfn_-to-device_entry-which-is-a-better-name.patch
mm-mmu_notifier-helper-to-test-if-a-range-invalidation-is-blockable.patch
mm-mmu_notifier-convert-user-range-blockable-to-helper-function.patch
mm-mmu_notifier-convert-mmu_notifier_range-blockable-to-a-flags.patch
mm-mmu_notifier-contextual-information-for-event-enums.patch
mm-mmu_notifier-contextual-information-for-event-triggering-invalidation-v2.patch
mm-mmu_notifier-use-correct-mmu_notifier-events-for-each-invalidation.patch
mm-mmu_notifier-pass-down-vma-and-reasons-why-mmu-notifier-is-happening-v2.patch
mm-mmu_notifier-mmu_notifier_range_update_to_read_only-helper.patch
