The patch titled
Subject: mm/hmm: add default fault flags to avoid the need to pre-fill pfns arrays.
has been added to the -mm tree. Its filename is
mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays.patch
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------------------------------------------------------
From: Jérôme Glisse <jglisse@xxxxxxxxxx>
Subject: mm/hmm: add default fault flags to avoid the need to pre-fill pfns arrays.
The HMM mirror API can be use in two fashions. The first one where the
HMM user coalesce multiple page faults into one request and set flags per
pfns for of those faults. The second one where the HMM user want to
pre-fault a range with specific flags. For the latter one it is a waste
to have the user pre-fill the pfn arrays with a default flags value.
This patch adds a default flags value allowing user to set them for a
range without having to pre-fill the pfn array.
Link: http://lkml.kernel.org/r/20190129165428.3931-7-jglisse@xxxxxxxxxx
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/hmm.h | 7 +++++++
mm/hmm.c | 12 ++++++++++++
2 files changed, 19 insertions(+)
--- a/include/linux/hmm.h~mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays
+++ a/include/linux/hmm.h
@@ -165,6 +165,8 @@ enum hmm_pfn_value_e {
* @pfns: array of pfns (big enough for the range)
* @flags: pfn flags to match device driver page table
* @values: pfn value for some special case (none, special, error, ...)
+ * @default_flags: default flags for the range (write, read, ...)
+ * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
* @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
* @valid: pfns array did not change since it has been fill by an HMM function
*/
@@ -177,6 +179,8 @@ struct hmm_range {
uint64_t *pfns;
const uint64_t *flags;
const uint64_t *values;
+ uint64_t default_flags;
+ uint64_t pfn_flags_mask;
uint8_t pfn_shift;
bool valid;
};
@@ -521,6 +525,9 @@ static inline int hmm_vma_fault(struct h
{
long ret;
+ range->default_flags = 0;
+ range->pfn_flags_mask = -1UL;
+
ret = hmm_range_register(range, range->vma->vm_mm,
range->start, range->end);
if (ret)
--- a/mm/hmm.c~mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays
+++ a/mm/hmm.c
@@ -423,6 +423,18 @@ static inline void hmm_pte_need_fault(co
if (!hmm_vma_walk->fault)
return;
+ /*
+ * So we not only consider the individual per page request we also
+ * consider the default flags requested for the range. The API can
+ * be use in 2 fashions. The first one where the HMM user coalesce
+ * multiple page fault into one request and set flags per pfns for
+ * of those faults. The second one where the HMM user want to pre-
+ * fault a range with specific flags. For the latter one it is a
+ * waste to have the user pre-fill the pfn arrays with a default
+ * flags value.
+ */
+ pfns = (pfns & range->pfn_flags_mask) | range->default_flags;
+
/* We aren't ask to do anything ... */
if (!(pfns & range->flags[HMM_PFN_VALID]))
return;
_
Patches currently in -mm which might be from jglisse@xxxxxxxxxx are
mm-hmm-use-reference-counting-for-hmm-struct.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.patch
mm-hmm-improve-and-rename-hmm_vma_fault-to-hmm_range_fault.patch
mm-hmm-improve-driver-api-to-work-and-wait-over-a-range.patch
mm-hmm-add-default-fault-flags-to-avoid-the-need-to-pre-fill-pfns-arrays.patch
mm-hmm-add-an-helper-function-that-fault-pages-and-map-them-to-a-device.patch
mm-hmm-support-hugetlbfs-snap-shoting-faulting-and-dma-mapping.patch
mm-hmm-allow-to-mirror-vma-of-a-file-on-a-dax-backed-filesystem.patch
mm-hmm-add-helpers-for-driver-to-safely-take-the-mmap_sem.patch
mm-mmu_notifier-contextual-information-for-event-triggering-invalidation-v2.patch
mm-mmu_notifier-contextual-information-for-event-triggering-invalidation-v2-fix.patch
