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>
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 3fec513..fbb35c7 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -145,6 +145,9 @@ enum hmm_pfn_value_e {
/*
* struct hmm_range - track invalidation lock on virtual address range
*
+ * @notifier: an optional mmu_interval_notifier
+ * @notifier_seq: when notifier is used this is the result of
+ * mmu_interval_read_begin()
* @hmm: the core HMM structure this range is active against
* @vma: the vm area struct for the range
* @list: all range lock are on a list
@@ -159,6 +162,8 @@ enum hmm_pfn_value_e {
* @valid: pfns array did not change since it has been fill by an HMM function
*/
struct hmm_range {
+ struct mmu_interval_notifier *notifier;
+ unsigned long notifier_seq;
struct hmm *hmm;
struct list_head list;
unsigned long start;