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Jason Gunthorpe

2019-Oct-29 19:25 UTC

[Nouveau] [PATCH v2 14/15] drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror

On Tue, Oct 29, 2019 at 07:22:37PM +0000, Yang, Philip
wrote:> Hi Jason,
> 
> I did quick test after merging amd-staging-drm-next with the 
> mmu_notifier branch, which includes this set changes. The test result 
> has different failures, app stuck intermittently, GUI no display etc. I 
> am understanding the changes and will try to figure out the cause.
Thanks! I'm not surprised by this given how difficult this patch was
to make. Let me know if I can assist in any way

Please ensure to run with lockdep enabled.. Your symptops sounds sort
of like deadlocking?

Regards,
Jason

Yang, Philip

2019-Nov-01 14:44 UTC

head link

[Nouveau] [PATCH v2 14/15] drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror

On 2019-10-29 3:25 p.m., Jason Gunthorpe wrote:> On Tue, Oct 29, 2019 at 07:22:37PM +0000, Yang, Philip wrote:
>> Hi Jason,
>>
>> I did quick test after merging amd-staging-drm-next with the
>> mmu_notifier branch, which includes this set changes. The test result
>> has different failures, app stuck intermittently, GUI no display etc. I
>> am understanding the changes and will try to figure out the cause.
> 
> Thanks! I'm not surprised by this given how difficult this patch was
> to make. Let me know if I can assist in any way
> 
> Please ensure to run with lockdep enabled.. Your symptops sounds sort
> of like deadlocking?
> Hi Jason,

Attached patch fix several issues in amdgpu driver, maybe you can squash 
this into patch 14. With this is done, patch 12, 13, 14 is Reviewed-by 
and Tested-by Philip Yang <philip.yang at amd.com>

Regards,
Philip
> Regards,
> Jason
> -------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-drm-amdgpu-issues-with-new-mmu_range_notifier-api.patch
Type: text/x-patch
Size: 5274 bytes
Desc: 0001-drm-amdgpu-issues-with-new-mmu_range_notifier-api.patch
URL:
<https://lists.freedesktop.org/archives/nouveau/attachments/20191101/40547648/attachment-0001.bin>

Jason Gunthorpe

2019-Nov-01 15:12 UTC

head link

[Nouveau] [PATCH v2 14/15] drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror

On Fri, Nov 01, 2019 at 02:44:51PM +0000, Yang, Philip
wrote:> 
> 
> On 2019-10-29 3:25 p.m., Jason Gunthorpe wrote:
> > On Tue, Oct 29, 2019 at 07:22:37PM +0000, Yang, Philip wrote:
> >> Hi Jason,
> >>
> >> I did quick test after merging amd-staging-drm-next with the
> >> mmu_notifier branch, which includes this set changes. The test
result
> >> has different failures, app stuck intermittently, GUI no display
etc. I
> >> am understanding the changes and will try to figure out the cause.
> > 
> > Thanks! I'm not surprised by this given how difficult this patch
was
> > to make. Let me know if I can assist in any way
> > 
> > Please ensure to run with lockdep enabled.. Your symptops sounds sort
> > of like deadlocking?
> > 
> Hi Jason,
> 
> Attached patch fix several issues in amdgpu driver, maybe you can squash 
> this into patch 14. With this is done, patch 12, 13, 14 is Reviewed-by 
> and Tested-by Philip Yang <philip.yang at amd.com>
Wow, this is great thanks! Can you clarify what the problems you found
were? Was the bug the 'return !r' below?

I'll also add your signed off by

Here are some remarks:
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> index cb718a064eb4..c8bbd06f1009 100644
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> @@ -67,21 +67,15 @@ static bool amdgpu_mn_invalidate_gfx(struct
mmu_range_notifier *mrn,
>  	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
>  	long r;
>  
> -	/*
> -	 * FIXME: Must hold some lock shared with
> -	 * amdgpu_ttm_tt_get_user_pages_done()
> -	 */
> -	mmu_range_set_seq(mrn, cur_seq);
> +	mutex_lock(&adev->notifier_lock);
>  
> -	/* FIXME: Is this necessary? */
> -	if (!amdgpu_ttm_tt_affect_userptr(bo->tbo.ttm, range->start,
> -					  range->end))
> -		return true;
> +	mmu_range_set_seq(mrn, cur_seq);
>  
> -	if (!mmu_notifier_range_blockable(range))
> +	if (!mmu_notifier_range_blockable(range)) {
> +		mutex_unlock(&adev->notifier_lock);
>  		return false;
This test for range_blockable should be before mutex_lock, I can move
it up

Also, do you know if notifier_lock is held while calling
amdgpu_ttm_tt_get_user_pages_done()? Can we add a 'lock assert held'
to amdgpu_ttm_tt_get_user_pages_done()?
> @@ -854,12 +853,20 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo
*bo, struct page **pages)
>  		r = -EPERM;
>  		goto out_unlock;
>  	}
> +	up_read(&mm->mmap_sem);
> +	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
> +
> +retry:
> +	range->notifier_seq = mmu_range_read_begin(&bo->notifier);
>  
> +	down_read(&mm->mmap_sem);
>  	r = hmm_range_fault(range, 0);
>  	up_read(&mm->mmap_sem);
> -
> -	if (unlikely(r < 0))
> +	if (unlikely(r <= 0)) {
> +		if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
> +			goto retry;
>  		goto out_free_pfns;
> +	}
This isn't really right, a retry loop like this needs to go all the
way to mmu_range_read_retry() and done under the notifier_lock. ie
mmu_range_read_retry() can fail just as likely as hmm_range_fault()
can, and drivers are supposed to retry in both cases, with a single
timeout.

AFAICT it is a major bug that many places ignore the return code of
amdgpu_ttm_tt_get_user_pages_done() ???

However, this is all pre-existing bugs, so I'm OK go ahead with this
patch as modified. I advise AMD to make a followup patch ..

I'll add a FIXME note to this effect.
>  	for (i = 0; i < ttm->num_pages; i++) {
>  		pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
> @@ -916,7 +923,7 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt
*ttm)
>  		gtt->range = NULL;
>  	}
>  
> -	return r;
> +	return !r;
Ah is this the major error? hmm_range_valid() is inverted vs
mmu_range_read_retry()?
>  }
>  #endif
>  
> @@ -997,10 +1004,18 @@ static void amdgpu_ttm_tt_unpin_userptr(struct
ttm_tt *ttm)
>  	sg_free_table(ttm->sg);
>  
>  #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
> -	if (gtt->range &&
> -	    ttm->pages[0] == hmm_device_entry_to_page(gtt->range,
> -						      gtt->range->pfns[0]))
> -		WARN_ONCE(1, "Missing get_user_page_done\n");
> +	if (gtt->range) {
> +		unsigned long i;
> +
> +		for (i = 0; i < ttm->num_pages; i++) {
> +			if (ttm->pages[i] !> +				hmm_device_entry_to_page(gtt->range,
> +					      gtt->range->pfns[i]))
> +				break;
> +		}
> +
> +		WARN((i == ttm->num_pages), "Missing
get_user_page_done\n");
> +	}
Is this related/necessary? I can put it in another patch if it is just
debugging improvement? Please advise

Thanks a lot,
Jason

Jason Gunthorpe

2019-Nov-01 18:21 UTC

head link

[Nouveau] [PATCH v2 14/15] drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror

On Fri, Nov 01, 2019 at 02:44:51PM +0000, Yang, Philip
wrote:> @@ -854,12 +853,20 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo
*bo, struct page **pages)
>  		r = -EPERM;
>  		goto out_unlock;
>  	}
> +	up_read(&mm->mmap_sem);
> +	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
> +
> +retry:
> +	range->notifier_seq = mmu_range_read_begin(&bo->notifier);
>  
> +	down_read(&mm->mmap_sem);
>  	r = hmm_range_fault(range, 0);
>  	up_read(&mm->mmap_sem);
> -
> -	if (unlikely(r < 0))
> +	if (unlikely(r <= 0)) {
> +		if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
> +			goto retry;
>  		goto out_free_pfns;
> +	}
I was reflecting on why this suddently became necessary, and I think
what might be happening is that hmm_range_fault() is trigging
invalidations as it runs (ie it is faulting in pages or something) and
that in turn causes the mrn to need retry.

The hmm version of this had a bug where a full
invalidate_range_start/end pair would not trigger retry, so this this
didn't happen.

This is unfortunate as the retry is unnecessary, but at this time I
can't think of a good way to separate an ignorable synchronous
invalidation caused by hmm_range_fault from an async one that cannot
be ignored..

A basic fix would be to not update the mrq seq in the notifier if
the invalidate is triggered by hmm_range_fault, but that seems
difficult to determine..

Any thoughts Jerome?

Jason

Jason Gunthorpe

2019-Nov-01 18:34 UTC

head link

[Nouveau] [PATCH v2a 14/15] drm/amdgpu: Use mmu_range_notifier instead of hmm_mirror

Convert the collision-retry lock around hmm_range_fault to use the one now
provided by the mmu_range notifier.

Although this driver does not seem to use the collision retry lock that
hmm provides correctly, it can still be converted over to use the
mmu_range_notifier api instead of hmm_mirror without too much trouble.

This also deletes another place where a driver is associating additional
data (struct amdgpu_mn) with a mmu_struct.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
Reviewed-by: Philip Yang <Philip.Yang at amd.com>
Tested-by: Philip Yang <Philip.Yang at amd.com>
Signed-off-by: Jason Gunthorpe <jgg at mellanox.com>
---
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |   4 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c        |  14 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c        | 150 ++----------------
 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h        |  49 ------
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       | 116 +++++++++-----
 5 files changed, 96 insertions(+), 237 deletions(-)

Philip, here is what it loos like after combining the two patches, thanks

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 47700302a08b7f..1bcedb9b477dce 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1738,6 +1738,10 @@ static int update_invalid_user_pages(struct
amdkfd_process_info *process_info,
 			return ret;
 		}
 
+		/*
+		 * FIXME: Cannot ignore the return code, must hold
+		 * notifier_lock
+		 */
 		amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
 
 		/* Mark the BO as valid unless it was invalidated
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 82823d9a8ba887..22c989bca7514c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -603,8 +603,6 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
 		e->tv.num_shared = 2;
 
 	amdgpu_bo_list_get_list(p->bo_list, &p->validated);
-	if (p->bo_list->first_userptr != p->bo_list->num_entries)
-		p->mn = amdgpu_mn_get(p->adev, AMDGPU_MN_TYPE_GFX);
 
 	INIT_LIST_HEAD(&duplicates);
 	amdgpu_vm_get_pd_bo(&fpriv->vm, &p->validated,
&p->vm_pd);
@@ -1287,11 +1285,11 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
 	if (r)
 		goto error_unlock;
 
-	/* No memory allocation is allowed while holding the mn lock.
-	 * p->mn is hold until amdgpu_cs_submit is finished and fence is added
-	 * to BOs.
+	/* No memory allocation is allowed while holding the notifier lock.
+	 * The lock is held until amdgpu_cs_submit is finished and fence is
+	 * added to BOs.
 	 */
-	amdgpu_mn_lock(p->mn);
+	mutex_lock(&p->adev->notifier_lock);
 
 	/* If userptr are invalidated after amdgpu_cs_parser_bos(), return
 	 * -EAGAIN, drmIoctl in libdrm will restart the amdgpu_cs_ioctl.
@@ -1334,13 +1332,13 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
 	amdgpu_vm_move_to_lru_tail(p->adev, &fpriv->vm);
 
 	ttm_eu_fence_buffer_objects(&p->ticket, &p->validated,
p->fence);
-	amdgpu_mn_unlock(p->mn);
+	mutex_unlock(&p->adev->notifier_lock);
 
 	return 0;
 
 error_abort:
 	drm_sched_job_cleanup(&job->base);
-	amdgpu_mn_unlock(p->mn);
+	mutex_unlock(&p->adev->notifier_lock);
 
 error_unlock:
 	amdgpu_job_free(job);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
index ac74320b71e4e7..f7be34907e54f5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
@@ -50,28 +50,6 @@
 #include "amdgpu.h"
 #include "amdgpu_amdkfd.h"
 
-/**
- * amdgpu_mn_lock - take the write side lock for this notifier
- *
- * @mn: our notifier
- */
-void amdgpu_mn_lock(struct amdgpu_mn *mn)
-{
-	if (mn)
-		down_write(&mn->lock);
-}
-
-/**
- * amdgpu_mn_unlock - drop the write side lock for this notifier
- *
- * @mn: our notifier
- */
-void amdgpu_mn_unlock(struct amdgpu_mn *mn)
-{
-	if (mn)
-		up_write(&mn->lock);
-}
-
 /**
  * amdgpu_mn_invalidate_gfx - callback to notify about mm change
  *
@@ -82,16 +60,20 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn)
  * potentially dirty.
  */
 static bool amdgpu_mn_invalidate_gfx(struct mmu_range_notifier *mrn,
-				     const struct mmu_notifier_range *range)
+				     const struct mmu_notifier_range *range,
+				     unsigned long cur_seq)
 {
 	struct amdgpu_bo *bo = container_of(mrn, struct amdgpu_bo, notifier);
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 	long r;
 
-	if (!mmu_notifier_range_blockable(range))
+	if (mmu_notifier_range_blockable(range))
+		mutex_lock(&adev->notifier_lock);
+	else if (!mutex_trylock(&adev->notifier_lock))
 		return false;
 
-	mutex_lock(&adev->notifier_lock);
+	mmu_range_set_seq(mrn, cur_seq);
+
 	r = dma_resv_wait_timeout_rcu(bo->tbo.base.resv, true, false,
 				      MAX_SCHEDULE_TIMEOUT);
 	mutex_unlock(&adev->notifier_lock);
@@ -114,15 +96,19 @@ static const struct mmu_range_notifier_ops
amdgpu_mn_gfx_ops = {
  * evicting all user-mode queues of the process.
  */
 static bool amdgpu_mn_invalidate_hsa(struct mmu_range_notifier *mrn,
-				     const struct mmu_notifier_range *range)
+				     const struct mmu_notifier_range *range,
+				     unsigned long cur_seq)
 {
 	struct amdgpu_bo *bo = container_of(mrn, struct amdgpu_bo, notifier);
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 
-	if (!mmu_notifier_range_blockable(range))
+	if (mmu_notifier_range_blockable(range))
+		mutex_lock(&adev->notifier_lock);
+	else if (!mutex_trylock(&adev->notifier_lock))
 		return false;
 
-	mutex_lock(&adev->notifier_lock);
+	mmu_range_set_seq(mrn, cur_seq);
+
 	amdgpu_amdkfd_evict_userptr(bo->kfd_bo, bo->notifier.mm);
 	mutex_unlock(&adev->notifier_lock);
 
@@ -133,92 +119,6 @@ static const struct mmu_range_notifier_ops
amdgpu_mn_hsa_ops = {
 	.invalidate = amdgpu_mn_invalidate_hsa,
 };
 
-static int amdgpu_mn_sync_pagetables(struct hmm_mirror *mirror,
-				     const struct mmu_notifier_range *update)
-{
-	struct amdgpu_mn *amn = container_of(mirror, struct amdgpu_mn, mirror);
-
-	if (!mmu_notifier_range_blockable(update))
-		return -EAGAIN;
-
-	down_read(&amn->lock);
-	up_read(&amn->lock);
-	return 0;
-}
-
-/* Low bits of any reasonable mm pointer will be unused due to struct
- * alignment. Use these bits to make a unique key from the mm pointer
- * and notifier type.
- */
-#define AMDGPU_MN_KEY(mm, type) ((unsigned long)(mm) + (type))
-
-static struct hmm_mirror_ops amdgpu_hmm_mirror_ops[] = {
-	[AMDGPU_MN_TYPE_GFX] = {
-		.sync_cpu_device_pagetables = amdgpu_mn_sync_pagetables,
-	},
-	[AMDGPU_MN_TYPE_HSA] = {
-		.sync_cpu_device_pagetables = amdgpu_mn_sync_pagetables,
-	},
-};
-
-/**
- * amdgpu_mn_get - create HMM mirror context
- *
- * @adev: amdgpu device pointer
- * @type: type of MMU notifier context
- *
- * Creates a HMM mirror context for current->mm.
- */
-struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
-				enum amdgpu_mn_type type)
-{
-	struct mm_struct *mm = current->mm;
-	struct amdgpu_mn *amn;
-	unsigned long key = AMDGPU_MN_KEY(mm, type);
-	int r;
-
-	mutex_lock(&adev->mn_lock);
-	if (down_write_killable(&mm->mmap_sem)) {
-		mutex_unlock(&adev->mn_lock);
-		return ERR_PTR(-EINTR);
-	}
-
-	hash_for_each_possible(adev->mn_hash, amn, node, key)
-		if (AMDGPU_MN_KEY(amn->mirror.hmm->mmu_notifier.mm,
-				  amn->type) == key)
-			goto release_locks;
-
-	amn = kzalloc(sizeof(*amn), GFP_KERNEL);
-	if (!amn) {
-		amn = ERR_PTR(-ENOMEM);
-		goto release_locks;
-	}
-
-	amn->adev = adev;
-	init_rwsem(&amn->lock);
-	amn->type = type;
-
-	amn->mirror.ops = &amdgpu_hmm_mirror_ops[type];
-	r = hmm_mirror_register(&amn->mirror, mm);
-	if (r)
-		goto free_amn;
-
-	hash_add(adev->mn_hash, &amn->node, AMDGPU_MN_KEY(mm, type));
-
-release_locks:
-	up_write(&mm->mmap_sem);
-	mutex_unlock(&adev->mn_lock);
-
-	return amn;
-
-free_amn:
-	up_write(&mm->mmap_sem);
-	mutex_unlock(&adev->mn_lock);
-	kfree(amn);
-
-	return ERR_PTR(r);
-}
-
 /**
  * amdgpu_mn_register - register a BO for notifier updates
  *
@@ -253,25 +153,3 @@ void amdgpu_mn_unregister(struct amdgpu_bo *bo)
 	mmu_range_notifier_remove(&bo->notifier);
 	bo->notifier.mm = NULL;
 }
-
-/* flags used by HMM internal, not related to CPU/GPU PTE flags */
-static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {
-		(1 << 0), /* HMM_PFN_VALID */
-		(1 << 1), /* HMM_PFN_WRITE */
-		0 /* HMM_PFN_DEVICE_PRIVATE */
-};
-
-static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {
-		0xfffffffffffffffeUL, /* HMM_PFN_ERROR */
-		0, /* HMM_PFN_NONE */
-		0xfffffffffffffffcUL /* HMM_PFN_SPECIAL */
-};
-
-void amdgpu_hmm_init_range(struct hmm_range *range)
-{
-	if (range) {
-		range->flags = hmm_range_flags;
-		range->values = hmm_range_values;
-		range->pfn_shift = PAGE_SHIFT;
-	}
-}
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
index d73ab2947b22b2..a292238f75ebae 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
@@ -30,59 +30,10 @@
 #include <linux/workqueue.h>
 #include <linux/interval_tree.h>
 
-enum amdgpu_mn_type {
-	AMDGPU_MN_TYPE_GFX,
-	AMDGPU_MN_TYPE_HSA,
-};
-
-/**
- * struct amdgpu_mn
- *
- * @adev: amdgpu device pointer
- * @type: type of MMU notifier
- * @work: destruction work item
- * @node: hash table node to find structure by adev and mn
- * @lock: rw semaphore protecting the notifier nodes
- * @mirror: HMM mirror function support
- *
- * Data for each amdgpu device and process address space.
- */
-struct amdgpu_mn {
-	/* constant after initialisation */
-	struct amdgpu_device	*adev;
-	enum amdgpu_mn_type	type;
-
-	/* only used on destruction */
-	struct work_struct	work;
-
-	/* protected by adev->mn_lock */
-	struct hlist_node	node;
-
-	/* objects protected by lock */
-	struct rw_semaphore	lock;
-
-#ifdef CONFIG_HMM_MIRROR
-	/* HMM mirror */
-	struct hmm_mirror	mirror;
-#endif
-};
-
 #if defined(CONFIG_HMM_MIRROR)
-void amdgpu_mn_lock(struct amdgpu_mn *mn);
-void amdgpu_mn_unlock(struct amdgpu_mn *mn);
-struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
-				enum amdgpu_mn_type type);
 int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr);
 void amdgpu_mn_unregister(struct amdgpu_bo *bo);
-void amdgpu_hmm_init_range(struct hmm_range *range);
 #else
-static inline void amdgpu_mn_lock(struct amdgpu_mn *mn) {}
-static inline void amdgpu_mn_unlock(struct amdgpu_mn *mn) {}
-static inline struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
-					      enum amdgpu_mn_type type)
-{
-	return NULL;
-}
 static inline int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr)
 {
 	DRM_WARN_ONCE("HMM_MIRROR kernel config option is not enabled, "
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index c0e41f1f0c2365..5f4d8ab76f1da0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -773,6 +773,20 @@ struct amdgpu_ttm_tt {
 #endif
 };
 
+#ifdef CONFIG_DRM_AMDGPU_USERPTR
+/* flags used by HMM internal, not related to CPU/GPU PTE flags */
+static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {
+	(1 << 0), /* HMM_PFN_VALID */
+	(1 << 1), /* HMM_PFN_WRITE */
+	0 /* HMM_PFN_DEVICE_PRIVATE */
+};
+
+static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {
+	0xfffffffffffffffeUL, /* HMM_PFN_ERROR */
+	0, /* HMM_PFN_NONE */
+	0xfffffffffffffffcUL /* HMM_PFN_SPECIAL */
+};
+
 /**
  * amdgpu_ttm_tt_get_user_pages - get device accessible pages that back user
  * memory and start HMM tracking CPU page table update
@@ -780,29 +794,28 @@ struct amdgpu_ttm_tt {
  * Calling function must call amdgpu_ttm_tt_userptr_range_done() once and only
  * once afterwards to stop HMM tracking
  */
-#if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
-
-#define MAX_RETRY_HMM_RANGE_FAULT	16
-
 int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 {
-	struct hmm_mirror *mirror = bo->mn ? &bo->mn->mirror : NULL;
 	struct ttm_tt *ttm = bo->tbo.ttm;
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
-	struct mm_struct *mm;
 	unsigned long start = gtt->userptr;
 	struct vm_area_struct *vma;
 	struct hmm_range *range;
+	unsigned long timeout;
+	struct mm_struct *mm;
 	unsigned long i;
-	uint64_t *pfns;
 	int r = 0;
 
-	if (unlikely(!mirror)) {
-		DRM_DEBUG_DRIVER("Failed to get hmm_mirror\n");
+	mm = bo->notifier.mm;
+	if (unlikely(!mm)) {
+		DRM_DEBUG_DRIVER("BO is not registered?\n");
 		return -EFAULT;
 	}
 
-	mm = mirror->hmm->mmu_notifier.mm;
+	/* Another get_user_pages is running at the same time?? */
+	if (WARN_ON(gtt->range))
+		return -EFAULT;
+
 	if (!mmget_not_zero(mm)) /* Happens during process shutdown */
 		return -ESRCH;
 
@@ -811,31 +824,23 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo,
struct page **pages)
 		r = -ENOMEM;
 		goto out;
 	}
+	range->notifier = &bo->notifier;
+	range->flags = hmm_range_flags;
+	range->values = hmm_range_values;
+	range->pfn_shift = PAGE_SHIFT;
+	range->start = bo->notifier.interval_tree.start;
+	range->end = bo->notifier.interval_tree.last + 1;
+	range->default_flags = hmm_range_flags[HMM_PFN_VALID];
+	if (!amdgpu_ttm_tt_is_readonly(ttm))
+		range->default_flags |= range->flags[HMM_PFN_WRITE];
 
-	pfns = kvmalloc_array(ttm->num_pages, sizeof(*pfns), GFP_KERNEL);
-	if (unlikely(!pfns)) {
+	range->pfns = kvmalloc_array(ttm->num_pages, sizeof(*range->pfns),
+				     GFP_KERNEL);
+	if (unlikely(!range->pfns)) {
 		r = -ENOMEM;
 		goto out_free_ranges;
 	}
 
-	amdgpu_hmm_init_range(range);
-	range->default_flags = range->flags[HMM_PFN_VALID];
-	range->default_flags |= amdgpu_ttm_tt_is_readonly(ttm) ?
-				0 : range->flags[HMM_PFN_WRITE];
-	range->pfn_flags_mask = 0;
-	range->pfns = pfns;
-	range->start = start;
-	range->end = start + ttm->num_pages * PAGE_SIZE;
-
-	hmm_range_register(range, mirror);
-
-	/*
-	 * Just wait for range to be valid, safe to ignore return value as we
-	 * will use the return value of hmm_range_fault() below under the
-	 * mmap_sem to ascertain the validity of the range.
-	 */
-	hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT);
-
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, start);
 	if (unlikely(!vma || start < vma->vm_start)) {
@@ -847,18 +852,31 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo,
struct page **pages)
 		r = -EPERM;
 		goto out_unlock;
 	}
+	up_read(&mm->mmap_sem);
+	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 
+retry:
+	range->notifier_seq = mmu_range_read_begin(&bo->notifier);
+
+	down_read(&mm->mmap_sem);
 	r = hmm_range_fault(range, 0);
 	up_read(&mm->mmap_sem);
-
-	if (unlikely(r < 0))
+	if (unlikely(r <= 0)) {
+		/*
+		 * FIXME: This timeout should encompass the retry from
+		 * mmu_range_read_retry() as well.
+		 */
+		if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
+			goto retry;
 		goto out_free_pfns;
+	}
 
 	for (i = 0; i < ttm->num_pages; i++) {
-		pages[i] = hmm_device_entry_to_page(range, pfns[i]);
+		/* FIXME: The pages cannot be touched outside the notifier_lock */
+		pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
 		if (unlikely(!pages[i])) {
 			pr_err("Page fault failed for pfn[%lu] = 0x%llx\n",
-			       i, pfns[i]);
+			       i, range->pfns[i]);
 			r = -ENOMEM;
 
 			goto out_free_pfns;
@@ -873,8 +891,7 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo,
struct page **pages)
 out_unlock:
 	up_read(&mm->mmap_sem);
 out_free_pfns:
-	hmm_range_unregister(range);
-	kvfree(pfns);
+	kvfree(range->pfns);
 out_free_ranges:
 	kfree(range);
 out:
@@ -903,15 +920,18 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm)
 		"No user pages to check\n");
 
 	if (gtt->range) {
-		r = hmm_range_valid(gtt->range);
-		hmm_range_unregister(gtt->range);
-
+		/*
+		 * FIXME: Must always hold notifier_lock for this, and must
+		 * not ignore the return code.
+		 */
+		r = mmu_range_read_retry(gtt->range->notifier,
+					 gtt->range->notifier_seq);
 		kvfree(gtt->range->pfns);
 		kfree(gtt->range);
 		gtt->range = NULL;
 	}
 
-	return r;
+	return !r;
 }
 #endif
 
@@ -992,10 +1012,18 @@ static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt
*ttm)
 	sg_free_table(ttm->sg);
 
 #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
-	if (gtt->range &&
-	    ttm->pages[0] == hmm_device_entry_to_page(gtt->range,
-						      gtt->range->pfns[0]))
-		WARN_ONCE(1, "Missing get_user_page_done\n");
+	if (gtt->range) {
+		unsigned long i;
+
+		for (i = 0; i < ttm->num_pages; i++) {
+			if (ttm->pages[i] !+				hmm_device_entry_to_page(gtt->range,
+					      gtt->range->pfns[i]))
+				break;
+		}
+
+		WARN((i == ttm->num_pages), "Missing get_user_page_done\n");
+	}
 #endif
 }
 
-- 
2.23.0

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