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authorJason Gunthorpe <jgg@mellanox.com>2019-11-12 16:22:20 -0400
committerJason Gunthorpe <jgg@mellanox.com>2019-11-23 19:56:44 -0400
commit04ec32fbc2b29a640d67872d2f88daac4c73e45b (patch)
tree35b141b60ac0b95cbaad2418b39fa7ec662c6cc1 /mm/hmm.c
parent99cb252f5e68d72afa3245a4e73d216d295cd335 (diff)
mm/hmm: allow hmm_range to be used with a mmu_interval_notifier or hmm_mirror
hmm_mirror's handling of ranges does not use a sequence count which results in this bug: CPU0 CPU1 hmm_range_wait_until_valid(range) valid == true hmm_range_fault(range) hmm_invalidate_range_start() range->valid = false hmm_invalidate_range_end() range->valid = true hmm_range_valid(range) valid == true Where the hmm_range_valid() should not have succeeded. Adding the required sequence count would make it nearly identical to the new mmu_interval_notifier. Instead replace the hmm_mirror stuff with mmu_interval_notifier. Co-existence of the two APIs is the first step. Link: https://lore.kernel.org/r/20191112202231.3856-4-jgg@ziepe.ca Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Tested-by: Philip Yang <Philip.Yang@amd.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r--mm/hmm.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index 6b0136665407..8d060c5dabe3 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -858,6 +858,14 @@ void hmm_range_unregister(struct hmm_range *range)
}
EXPORT_SYMBOL(hmm_range_unregister);
+static bool needs_retry(struct hmm_range *range)
+{
+ if (range->notifier)
+ return mmu_interval_check_retry(range->notifier,
+ range->notifier_seq);
+ return !range->valid;
+}
+
static const struct mm_walk_ops hmm_walk_ops = {
.pud_entry = hmm_vma_walk_pud,
.pmd_entry = hmm_vma_walk_pmd,
@@ -898,18 +906,23 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
unsigned long start = range->start, end;
struct hmm_vma_walk hmm_vma_walk;
- struct hmm *hmm = range->hmm;
+ struct mm_struct *mm;
struct vm_area_struct *vma;
int ret;
- lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem);
+ if (range->notifier)
+ mm = range->notifier->mm;
+ else
+ mm = range->hmm->mmu_notifier.mm;
+
+ lockdep_assert_held(&mm->mmap_sem);
do {
/* If range is no longer valid force retry. */
- if (!range->valid)
+ if (needs_retry(range))
return -EBUSY;
- vma = find_vma(hmm->mmu_notifier.mm, start);
+ vma = find_vma(mm, start);
if (vma == NULL || (vma->vm_flags & device_vma))
return -EFAULT;
@@ -939,7 +952,7 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
start = hmm_vma_walk.last;
/* Keep trying while the range is valid. */
- } while (ret == -EBUSY && range->valid);
+ } while (ret == -EBUSY && !needs_retry(range));
if (ret) {
unsigned long i;
@@ -997,7 +1010,7 @@ long hmm_range_dma_map(struct hmm_range *range, struct device *device,
continue;
/* Check if range is being invalidated */
- if (!range->valid) {
+ if (needs_retry(range)) {
ret = -EBUSY;
goto unmap;
}