Commit e36acfe6 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register 



Ralph observes that hmm_range_register() can only be called by a driver
while a mirror is registered. Make this clear in the API by passing in the
mirror structure as a parameter.

This also simplifies understanding the lifetime model for struct hmm, as
the hmm pointer must be valid as part of a registered mirror so all we
need in hmm_register_range() is a simple kref_get.

Suggested-by: default avatarRalph Campbell <rcampbell@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarRalph Campbell <rcampbell@nvidia.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarPhilip Yang <Philip.Yang@amd.com>
parent 6d7c3cde

drivers/gpu/drm/nouveau/nouveau_svm.c

+1 −1
Original line number Diff line number Diff line
@@ -649,7 +649,7 @@ nouveau_svm_fault(struct nvif_notify *notify) 
		range.values = nouveau_svm_pfn_values;

		range.pfn_shift = NVIF_VMM_PFNMAP_V0_ADDR_SHIFT;

again:

		ret = hmm_vma_fault(&range, true);

		ret = hmm_vma_fault(&svmm->mirror, &range, true);

		if (ret == 0) {

			mutex_lock(&svmm->mutex);

			if (!hmm_vma_range_done(&range)) {

include/linux/hmm.h

+4 −3
Original line number Diff line number Diff line
@@ -496,7 +496,7 @@ static inline bool hmm_mirror_mm_is_alive(struct hmm_mirror *mirror) 
 * Please see Documentation/vm/hmm.rst for how to use the range API.

 */

int hmm_range_register(struct hmm_range *range,

		       struct mm_struct *mm,

		       struct hmm_mirror *mirror,

		       unsigned long start,

		       unsigned long end,

		       unsigned page_shift);
@@ -532,7 +532,8 @@ static inline bool hmm_vma_range_done(struct hmm_range *range) 
}



/* This is a temporary helper to avoid merge conflict between trees. */

static inline int hmm_vma_fault(struct hmm_range *range, bool block)

static inline int hmm_vma_fault(struct hmm_mirror *mirror,

				struct hmm_range *range, bool block)

{

	long ret;
@@ -545,7 +546,7 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block) 
	range->default_flags = 0;

	range->pfn_flags_mask = -1UL;



	ret = hmm_range_register(range, range->vma->vm_mm,

	ret = hmm_range_register(range, mirror,

				 range->start, range->end,

				 PAGE_SHIFT);

	if (ret)

mm/hmm.c

+4 −9
Original line number Diff line number Diff line
@@ -914,13 +914,13 @@ static void hmm_pfns_clear(struct hmm_range *range, 
 * Track updates to the CPU page table see include/linux/hmm.h

 */

int hmm_range_register(struct hmm_range *range,

		       struct mm_struct *mm,

		       struct hmm_mirror *mirror,

		       unsigned long start,

		       unsigned long end,

		       unsigned page_shift)

{

	unsigned long mask = ((1UL << page_shift) - 1UL);

	struct hmm *hmm;

	struct hmm *hmm = mirror->hmm;



	range->valid = false;

	range->hmm = NULL;
@@ -934,20 +934,15 @@ int hmm_range_register(struct hmm_range *range, 
	range->start = start;

	range->end = end;



	hmm = hmm_get_or_create(mm);

	if (!hmm)

		return -EFAULT;



	/* Check if hmm_mm_destroy() was call. */

	if (hmm->mm == NULL || hmm->dead) {

		hmm_put(hmm);

	if (hmm->mm == NULL || hmm->dead)

		return -EFAULT;

	}



	/* Initialize range to track CPU page table updates. */

	mutex_lock(&hmm->lock);



	range->hmm = hmm;

	kref_get(&hmm->kref);

	list_add_rcu(&range->list, &hmm->ranges);



	/*

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