Re: [PATCH v2] drm/xe/madvise: Track purgeability with BO-local counters

["Yadav, Arvind" <arvind.yadav@intel.com>]

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On 01-05-2026 23:38, Matthew Brost wrote:
> On Thu, Apr 30, 2026 at 12:36:41PM -0700, Matthew Brost wrote:
>> On Thu, Apr 30, 2026 at 03:41:30PM +0530, Arvind Yadav wrote:
>>> xe_bo_recompute_purgeable_state() walks all VMAs of a BO to determine
>>> whether the BO can be made purgeable. This makes VMA create/destroy and
>>> madvise updates O(n) in the number of mappings.
>>>
>>> Replace the walk with BO-local counters protected by the BO dma-resv
>>> lock:
>>>
>>>    - vma_count tracks the number of VMAs mapping the BO.
>>>    - willneed_count tracks active WILLNEED holders, including WILLNEED
>>>      VMAs and active dma-buf exports for non-imported BOs.
>>>
>>> A DONTNEED BO is promoted back to WILLNEED on a 0->1 transition of
>>> willneed_count. A BO is demoted to DONTNEED on a 1->0 transition only
>>> when it still has VMAs, preserving the previous behaviour where a BO
>>> with no mappings keeps its current madvise state.
>>>
>>> PURGED remains terminal, preserving the existing "once purged, always
>>> purged" rule.
>>>
>>> v2:
>>>    - Use early return for imported BOs in all four helpers to avoid
>>>      nesting (Matt B).
>>>    - Group purgeability state into a purgeable sub-struct on struct
>>>      xe_bo (Matt B).
>>>    - Reword xe_bo_willneed_put_locked() kernel-doc to explain that a 1->0
>>>      transition means all remaining active VMAs are DONTNEED (Matt B).
>>>
>>> Suggested-by: Thomas Hellström<thomas.hellstrom@linux.intel.com>
>>> Cc: Matthew Brost<matthew.brost@intel.com>
>> Reviewed-by: Matthew Brost<matthew.brost@intel.com>
>>
> My bad - sashiko flagged a valid issue here [1].
>
> So I xe_vma_create need to flags.check_purged check that is currently in
> vma_lock_and_validate(). We the dma-resv locks in xe_vma_create so
> moving the check to xe_vma_create should be safe.
>
> More below.
>
> [1]https://sashiko.dev/#/patchset/20260430101130.1365878-1-arvind.yadav%40intel.com


Yes, Good catch. we should add the check in xe_vma_create(), but it also 
needs to remain in vma_lock_and_validate() because PREFETCH does not go 
through xe_vma_create(). drm_gpuvm_prefetch_ops_create() generates 
operations that reference existing VMAs, and the PREFETCH path in 
op_lock_and_prep() relies solely on vma_lock_and_validate().

>
>>> Cc: Thomas Hellström<thomas.hellstrom@linux.intel.com>
>>> Cc: Himal Prasad Ghimiray<himal.prasad.ghimiray@intel.com>
>>> Signed-off-by: Arvind Yadav<arvind.yadav@intel.com>
>>> ---
>>>   drivers/gpu/drm/xe/xe_bo.c         |   6 +-
>>>   drivers/gpu/drm/xe/xe_bo.h         |  88 +++++++++++++++-
>>>   drivers/gpu/drm/xe/xe_bo_types.h   |  27 ++++-
>>>   drivers/gpu/drm/xe/xe_dma_buf.c    |  28 ++++-
>>>   drivers/gpu/drm/xe/xe_vm.c         |   9 +-
>>>   drivers/gpu/drm/xe/xe_vm_madvise.c | 162 ++---------------------------
>>>   drivers/gpu/drm/xe/xe_vm_madvise.h |   2 -
>>>   7 files changed, 155 insertions(+), 167 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
>>> index 5ce60d161e09..eaa3a4ee9111 100644
>>> --- a/drivers/gpu/drm/xe/xe_bo.c
>>> +++ b/drivers/gpu/drm/xe/xe_bo.c
>>> @@ -884,10 +884,10 @@ void xe_bo_set_purgeable_state(struct xe_bo *bo,
>>>   		  new_state == XE_MADV_PURGEABLE_PURGED);
>>>   
>>>   	/* Once purged, always purged - cannot transition out */
>>> -	xe_assert(xe, !(bo->madv_purgeable == XE_MADV_PURGEABLE_PURGED &&
>>> +	xe_assert(xe, !(bo->purgeable.state == XE_MADV_PURGEABLE_PURGED &&
>>>   			new_state != XE_MADV_PURGEABLE_PURGED));
>>>   
>>> -	bo->madv_purgeable = new_state;
>>> +	bo->purgeable.state = new_state;
>>>   	xe_bo_set_purgeable_shrinker(bo, new_state);
>>>   }
>>>   
>>> @@ -2355,7 +2355,7 @@ struct xe_bo *xe_bo_init_locked(struct xe_device *xe, struct xe_bo *bo,
>>>   	INIT_LIST_HEAD(&bo->vram_userfault_link);
>>>   
>>>   	/* Initialize purge advisory state */
>>> -	bo->madv_purgeable = XE_MADV_PURGEABLE_WILLNEED;
>>> +	bo->purgeable.state = XE_MADV_PURGEABLE_WILLNEED;
>>>   
>>>   	drm_gem_private_object_init(&xe->drm, &bo->ttm.base, size);
>>>   
>>> diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
>>> index 68dea7d25a6b..6340317f7d2e 100644
>>> --- a/drivers/gpu/drm/xe/xe_bo.h
>>> +++ b/drivers/gpu/drm/xe/xe_bo.h
>>> @@ -251,7 +251,7 @@ static inline bool xe_bo_is_protected(const struct xe_bo *bo)
>>>   static inline bool xe_bo_is_purged(struct xe_bo *bo)
>>>   {
>>>   	xe_bo_assert_held(bo);
>>> -	return bo->madv_purgeable == XE_MADV_PURGEABLE_PURGED;
>>> +	return bo->purgeable.state == XE_MADV_PURGEABLE_PURGED;
>>>   }
>>>   
>>>   /**
>>> @@ -268,11 +268,95 @@ static inline bool xe_bo_is_purged(struct xe_bo *bo)
>>>   static inline bool xe_bo_madv_is_dontneed(struct xe_bo *bo)
>>>   {
>>>   	xe_bo_assert_held(bo);
>>> -	return bo->madv_purgeable == XE_MADV_PURGEABLE_DONTNEED;
>>> +	return bo->purgeable.state == XE_MADV_PURGEABLE_DONTNEED;
>>>   }
>>>   
>>>   void xe_bo_set_purgeable_state(struct xe_bo *bo, enum xe_madv_purgeable_state new_state);
>>>   
>>> +/**
>>> + * xe_bo_willneed_get_locked() - Acquire a WILLNEED holder on a BO
>>> + * @bo: Buffer object
>>> + *
>>> + * Increments willneed_count and, on a 0->1 transition, promotes the BO
>>> + * from DONTNEED to WILLNEED. PURGED is terminal and is never modified.
>>> + *
>>> + * Caller must hold the BO's dma-resv lock.
>>> + */
>>> +static inline void xe_bo_willneed_get_locked(struct xe_bo *bo)
>>> +{
>>> +	xe_bo_assert_held(bo);
>>> +
>>> +	/* Imported BOs are owned externally; do not track purgeability. */
>>> +	if (drm_gem_is_imported(&bo->ttm.base))
>>> +		return;
>>> +
>>> +	if (bo->purgeable.willneed_count++ == 0 && xe_bo_madv_is_dontneed(bo))
>>> +		xe_bo_set_purgeable_state(bo, XE_MADV_PURGEABLE_WILLNEED);
>>> +}
>>> +
>>> +/**
>>> + * xe_bo_willneed_put_locked() - Release a WILLNEED holder on a BO
>>> + * @bo: Buffer object
>>> + *
>>> + * Decrements willneed_count and, on a 1->0 transition, marks the BO
>>> + * DONTNEED only if it still has VMAs (implying all active VMAs are
>>> + * DONTNEED). If the last VMA is being removed, preserve the current BO
>>> + * state to match the previous VMA-walk semantics.
>>> + *
>>> + * PURGED is terminal and the BO state is never modified.
>>> + *
>>> + * Caller must hold the BO's dma-resv lock.
>>> + */
>>> +static inline void xe_bo_willneed_put_locked(struct xe_bo *bo)
>>> +{
>>> +	xe_bo_assert_held(bo);
>>> +
>>> +	if (drm_gem_is_imported(&bo->ttm.base))
>>> +		return;
>>> +
>>> +	xe_assert(xe_bo_device(bo), bo->purgeable.willneed_count > 0);
>>> +	if (--bo->purgeable.willneed_count == 0 && bo->purgeable.vma_count > 0 &&
>>> +	    !xe_bo_is_purged(bo))
>>> +		xe_bo_set_purgeable_state(bo, XE_MADV_PURGEABLE_DONTNEED);
>>> +}
>>> +
>>> +/**
>>> + * xe_bo_vma_count_inc_locked() - Account a new VMA on a BO
>>> + * @bo: Buffer object
>>> + *
>>> + * Increments vma_count.
>>> + *
>>> + * Caller must hold the BO's dma-resv lock.
>>> + */
>>> +static inline void xe_bo_vma_count_inc_locked(struct xe_bo *bo)
>>> +{
>>> +	xe_bo_assert_held(bo);
>>> +
>>> +	if (drm_gem_is_imported(&bo->ttm.base))
>>> +		return;
>>> +
>>> +	bo->purgeable.vma_count++;
>>> +}
>>> +
>>> +/**
>>> + * xe_bo_vma_count_dec_locked() - Account a VMA removal on a BO
>>> + * @bo: Buffer object
>>> + *
>>> + * Decrements vma_count.
>>> + *
>>> + * Caller must hold the BO's dma-resv lock.
>>> + */
>>> +static inline void xe_bo_vma_count_dec_locked(struct xe_bo *bo)
>>> +{
>>> +	xe_bo_assert_held(bo);
>>> +
>>> +	if (drm_gem_is_imported(&bo->ttm.base))
>>> +		return;
>>> +
>>> +	xe_assert(xe_bo_device(bo), bo->purgeable.vma_count > 0);
>>> +	bo->purgeable.vma_count--;
>>> +}
>>> +
>>>   static inline void xe_bo_unpin_map_no_vm(struct xe_bo *bo)
>>>   {
>>>   	if (likely(bo)) {
>>> diff --git a/drivers/gpu/drm/xe/xe_bo_types.h b/drivers/gpu/drm/xe/xe_bo_types.h
>>> index 9c199badd9b2..6756d7820aca 100644
>>> --- a/drivers/gpu/drm/xe/xe_bo_types.h
>>> +++ b/drivers/gpu/drm/xe/xe_bo_types.h
>>> @@ -111,10 +111,31 @@ struct xe_bo {
>>>   	u64 min_align;
>>>   
>>>   	/**
>>> -	 * @madv_purgeable: user space advise on BO purgeability, protected
>>> -	 * by BO's dma-resv lock.
>>> +	 * @purgeable: Purgeability state and accounting.
>>> +	 *
>>> +	 * All fields are protected by the BO's dma-resv lock.
>>>   	 */
>>> -	u32 madv_purgeable;
>>> +	struct {
>>> +		/**
>>> +		 * @purgeable.state: BO purgeability state (WILLNEED/DONTNEED/PURGED).
>>> +		 */
>>> +		u32 state;
>>> +
>>> +		/**
>>> +		 * @purgeable.vma_count: Number of VMAs currently mapping this BO.
>>> +		 */
>>> +		u32 vma_count;
>>> +
>>> +		/**
>>> +		 * @purgeable.willneed_count: Number of active WILLNEED holders.
>>> +		 *
>>> +		 * Counts WILLNEED VMAs plus active dma-buf exports for
>>> +		 * non-imported BOs. The BO flips to DONTNEED on a 1->0
>>> +		 * transition only when VMAs still exist; if the last VMA is
>>> +		 * removed, the previous BO state is preserved.
>>> +		 */
>>> +		u32 willneed_count;
>>> +	} purgeable;
>>>   };
>>>   
>>>   #endif
>>> diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
>>> index b9828da15897..855d32ba314d 100644
>>> --- a/drivers/gpu/drm/xe/xe_dma_buf.c
>>> +++ b/drivers/gpu/drm/xe/xe_dma_buf.c
>>> @@ -193,6 +193,18 @@ static int xe_dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
>>>   	return 0;
>>>   }
>>>   
>>> +static void xe_dma_buf_release(struct dma_buf *dmabuf)
>>> +{
>>> +	struct drm_gem_object *obj = dmabuf->priv;
>>> +	struct xe_bo *bo = gem_to_xe_bo(obj);
>>> +
>>> +	xe_bo_lock(bo, false);
>>> +	xe_bo_willneed_put_locked(bo);
>>> +	xe_bo_unlock(bo);
>>> +
>>> +	drm_gem_dmabuf_release(dmabuf);
>>> +}
>>> +
>>>   static const struct dma_buf_ops xe_dmabuf_ops = {
>>>   	.attach = xe_dma_buf_attach,
>>>   	.detach = xe_dma_buf_detach,
>>> @@ -200,7 +212,7 @@ static const struct dma_buf_ops xe_dmabuf_ops = {
>>>   	.unpin = xe_dma_buf_unpin,
>>>   	.map_dma_buf = xe_dma_buf_map,
>>>   	.unmap_dma_buf = xe_dma_buf_unmap,
>>> -	.release = drm_gem_dmabuf_release,
>>> +	.release = xe_dma_buf_release,
>>>   	.begin_cpu_access = xe_dma_buf_begin_cpu_access,
>>>   	.mmap = drm_gem_dmabuf_mmap,
>>>   	.vmap = drm_gem_dmabuf_vmap,
>>> @@ -241,18 +253,26 @@ struct dma_buf *xe_gem_prime_export(struct drm_gem_object *obj, int flags)
>>>   		ret = -EINVAL;
>>>   		goto out_unlock;
>>>   	}
>>> +
>>> +	xe_bo_willneed_get_locked(bo);
>>>   	xe_bo_unlock(bo);
>>>   
>>>   	ret = ttm_bo_setup_export(&bo->ttm, &ctx);
>>>   	if (ret)
>>> -		return ERR_PTR(ret);
>>> +		goto out_put;
>>>   
>>>   	buf = drm_gem_prime_export(obj, flags);
>>> -	if (!IS_ERR(buf))
>>> -		buf->ops = &xe_dmabuf_ops;
>>> +	if (IS_ERR(buf)) {
>>> +		ret = PTR_ERR(buf);
>>> +		goto out_put;
>>> +	}
>>>   
>>> +	buf->ops = &xe_dmabuf_ops;
>>>   	return buf;
>>>   
>>> +out_put:
>>> +	xe_bo_lock(bo, false);
>>> +	xe_bo_willneed_put_locked(bo);
>>>   out_unlock:
>>>   	xe_bo_unlock(bo);
>>>   	return ERR_PTR(ret);
>>> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
>>> index c3836f6eab35..12457173ba85 100644
>>> --- a/drivers/gpu/drm/xe/xe_vm.c
>>> +++ b/drivers/gpu/drm/xe/xe_vm.c
>>> @@ -1131,6 +1131,10 @@ static struct xe_vma *xe_vma_create(struct xe_vm *vm,
>>>   		vma->gpuva.gem.offset = bo_offset_or_userptr;
>>>   		drm_gpuva_link(&vma->gpuva, vm_bo);
>>>   		drm_gpuvm_bo_put(vm_bo);
>>> +
>>> +		xe_bo_vma_count_inc_locked(bo);
>>> +		if (vma->attr.purgeable_state == XE_MADV_PURGEABLE_WILLNEED)
>>> +			xe_bo_willneed_get_locked(bo);
> So at very top of this function I think:
>
> if (bo && attr->purgeable_state == XE_MADV_PURGEABLE_WILLNEED) {
> 	if (xe_bo_madv_is_dontneed(bo))
> 		return ERR_PTR(-EBUSY);  /* BO marked purgeable */
> 	else if (xe_bo_is_purged(bo))
> 		return ERR_PTR(-EINVAL); /* BO already purged */
> }
>
> Then delete the check in vma_lock_and_validate. I think check in
> vma_lock_and_validate is actually wrong for rebinds too - e.g., it is
> prefectly to do a partial unbind a dontneed or purged BO and the
> existing check I believe would reject this.


Agreed. I will dropped .check_purged from MAP and REMAP prev/next in 
vm_bind_ioctl_op_lock_and_prep() for v3. The check now lives in 
xe_vma_create() and only triggers when attr->purgeable_state == 
WILLNEED, so partial unbind/rebind on DONTNEED or PURGED BOs works as 
expected. and PREFETCH keeps .check_purged as it is a separate check for 
existing VMAs with no backing store to migrate.

>
> We should put together a test for for this too.
>
> addr = bind(2M);
> madvise(addr, DONTNEED);
> unbind(addr, 1M);
>
> Assuming the current code fails in this test case and new code works,
> I'd suggest making this patch a fixes too.


Noted. I will add a test case to cover this and include the appropriate 
fix tag

Thanks,
Arvind

>
> Matt
>
>>>   	} else /* userptr or null */ {
>>>   		if (!is_null && !is_cpu_addr_mirror) {
>>>   			struct xe_userptr_vma *uvma = to_userptr_vma(vma);
>>> @@ -1208,7 +1212,10 @@ static void xe_vma_destroy(struct xe_vma *vma, struct dma_fence *fence)
>>>   		xe_bo_assert_held(bo);
>>>   
>>>   		drm_gpuva_unlink(&vma->gpuva);
>>> -		xe_bo_recompute_purgeable_state(bo);
>>> +
>>> +		xe_bo_vma_count_dec_locked(bo);
>>> +		if (vma->attr.purgeable_state == XE_MADV_PURGEABLE_WILLNEED)
>>> +			xe_bo_willneed_put_locked(bo);
>>>   	}
>>>   
>>>   	xe_vm_assert_held(vm);
>>> diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.c b/drivers/gpu/drm/xe/xe_vm_madvise.c
>>> index c78906dea82b..c4fb29004195 100644
>>> --- a/drivers/gpu/drm/xe/xe_vm_madvise.c
>>> +++ b/drivers/gpu/drm/xe/xe_vm_madvise.c
>>> @@ -185,147 +185,6 @@ static void madvise_pat_index(struct xe_device *xe, struct xe_vm *vm,
>>>   	}
>>>   }
>>>   
>>> -/**
>>> - * xe_bo_is_dmabuf_shared() - Check if BO is shared via dma-buf
>>> - * @bo: Buffer object
>>> - *
>>> - * Prevent marking imported or exported dma-bufs as purgeable.
>>> - * For imported BOs, Xe doesn't own the backing store and cannot
>>> - * safely reclaim pages (exporter or other devices may still be
>>> - * using them). For exported BOs, external devices may have active
>>> - * mappings we cannot track.
>>> - *
>>> - * Return: true if BO is imported or exported, false otherwise
>>> - */
>>> -static bool xe_bo_is_dmabuf_shared(struct xe_bo *bo)
>>> -{
>>> -	struct drm_gem_object *obj = &bo->ttm.base;
>>> -
>>> -	/* Imported: exporter owns backing store */
>>> -	if (drm_gem_is_imported(obj))
>>> -		return true;
>>> -
>>> -	/* Exported: external devices may be accessing */
>>> -	if (obj->dma_buf)
>>> -		return true;
>>> -
>>> -	return false;
>>> -}
>>> -
>>> -/**
>>> - * enum xe_bo_vmas_purge_state - VMA purgeable state aggregation
>>> - *
>>> - * Distinguishes whether a BO's VMAs are all DONTNEED, have at least
>>> - * one WILLNEED, or have no VMAs at all.
>>> - *
>>> - * Enum values align with XE_MADV_PURGEABLE_* states for consistency.
>>> - */
>>> -enum xe_bo_vmas_purge_state {
>>> -	/** @XE_BO_VMAS_STATE_WILLNEED: At least one VMA is WILLNEED */
>>> -	XE_BO_VMAS_STATE_WILLNEED = 0,
>>> -	/** @XE_BO_VMAS_STATE_DONTNEED: All VMAs are DONTNEED */
>>> -	XE_BO_VMAS_STATE_DONTNEED = 1,
>>> -	/** @XE_BO_VMAS_STATE_NO_VMAS: BO has no VMAs */
>>> -	XE_BO_VMAS_STATE_NO_VMAS = 2,
>>> -};
>>> -
>>> -/*
>>> - * xe_bo_recompute_purgeable_state() casts between xe_bo_vmas_purge_state and
>>> - * xe_madv_purgeable_state. Enforce that WILLNEED=0 and DONTNEED=1 match across
>>> - * both enums so the single-line cast is always valid.
>>> - */
>>> -static_assert(XE_BO_VMAS_STATE_WILLNEED == (int)XE_MADV_PURGEABLE_WILLNEED,
>>> -	      "VMA purge state WILLNEED must equal madv purgeable WILLNEED");
>>> -static_assert(XE_BO_VMAS_STATE_DONTNEED == (int)XE_MADV_PURGEABLE_DONTNEED,
>>> -	      "VMA purge state DONTNEED must equal madv purgeable DONTNEED");
>>> -
>>> -/**
>>> - * xe_bo_all_vmas_dontneed() - Determine BO VMA purgeable state
>>> - * @bo: Buffer object
>>> - *
>>> - * Check all VMAs across all VMs to determine aggregate purgeable state.
>>> - * Shared BOs require unanimous DONTNEED state from all mappings.
>>> - *
>>> - * Caller must hold BO dma-resv lock.
>>> - *
>>> - * Return: XE_BO_VMAS_STATE_DONTNEED if all VMAs are DONTNEED,
>>> - *         XE_BO_VMAS_STATE_WILLNEED if at least one VMA is not DONTNEED,
>>> - *         XE_BO_VMAS_STATE_NO_VMAS if BO has no VMAs
>>> - */
>>> -static enum xe_bo_vmas_purge_state xe_bo_all_vmas_dontneed(struct xe_bo *bo)
>>> -{
>>> -	struct drm_gpuvm_bo *vm_bo;
>>> -	struct drm_gpuva *gpuva;
>>> -	struct drm_gem_object *obj = &bo->ttm.base;
>>> -	bool has_vmas = false;
>>> -
>>> -	xe_bo_assert_held(bo);
>>> -
>>> -	/* Shared dma-bufs cannot be purgeable */
>>> -	if (xe_bo_is_dmabuf_shared(bo))
>>> -		return XE_BO_VMAS_STATE_WILLNEED;
>>> -
>>> -	drm_gem_for_each_gpuvm_bo(vm_bo, obj) {
>>> -		drm_gpuvm_bo_for_each_va(gpuva, vm_bo) {
>>> -			struct xe_vma *vma = gpuva_to_vma(gpuva);
>>> -
>>> -			has_vmas = true;
>>> -
>>> -			/* Any non-DONTNEED VMA prevents purging */
>>> -			if (vma->attr.purgeable_state != XE_MADV_PURGEABLE_DONTNEED)
>>> -				return XE_BO_VMAS_STATE_WILLNEED;
>>> -		}
>>> -	}
>>> -
>>> -	/*
>>> -	 * No VMAs => preserve existing BO purgeable state.
>>> -	 * Avoids incorrectly flipping DONTNEED -> WILLNEED when last VMA unmapped.
>>> -	 */
>>> -	if (!has_vmas)
>>> -		return XE_BO_VMAS_STATE_NO_VMAS;
>>> -
>>> -	return XE_BO_VMAS_STATE_DONTNEED;
>>> -}
>>> -
>>> -/**
>>> - * xe_bo_recompute_purgeable_state() - Recompute BO purgeable state from VMAs
>>> - * @bo: Buffer object
>>> - *
>>> - * Walk all VMAs to determine if BO should be purgeable or not.
>>> - * Shared BOs require unanimous DONTNEED state from all mappings.
>>> - * If the BO has no VMAs the existing state is preserved.
>>> - *
>>> - * Locking: Caller must hold BO dma-resv lock. When iterating GPUVM lists,
>>> - * VM lock must also be held (write) to prevent concurrent VMA modifications.
>>> - * This is satisfied at both call sites:
>>> - * - xe_vma_destroy(): holds vm->lock write
>>> - * - madvise_purgeable(): holds vm->lock write (from madvise ioctl path)
>>> - *
>>> - * Return: nothing
>>> - */
>>> -void xe_bo_recompute_purgeable_state(struct xe_bo *bo)
>>> -{
>>> -	enum xe_bo_vmas_purge_state vma_state;
>>> -
>>> -	if (!bo)
>>> -		return;
>>> -
>>> -	xe_bo_assert_held(bo);
>>> -
>>> -	/*
>>> -	 * Once purged, always purged. Cannot transition back to WILLNEED.
>>> -	 * This matches i915 semantics where purged BOs are permanently invalid.
>>> -	 */
>>> -	if (bo->madv_purgeable == XE_MADV_PURGEABLE_PURGED)
>>> -		return;
>>> -
>>> -	vma_state = xe_bo_all_vmas_dontneed(bo);
>>> -
>>> -	if (vma_state != (enum xe_bo_vmas_purge_state)bo->madv_purgeable &&
>>> -	    vma_state != XE_BO_VMAS_STATE_NO_VMAS)
>>> -		xe_bo_set_purgeable_state(bo, (enum xe_madv_purgeable_state)vma_state);
>>> -}
>>> -
>>>   /**
>>>    * madvise_purgeable - Handle purgeable buffer object advice
>>>    * @xe: XE device
>>> @@ -359,12 +218,6 @@ static void madvise_purgeable(struct xe_device *xe, struct xe_vm *vm,
>>>   		/* BO must be locked before modifying madv state */
>>>   		xe_bo_assert_held(bo);
>>>   
>>> -		/* Skip shared dma-bufs - no PTEs to zap */
>>> -		if (xe_bo_is_dmabuf_shared(bo)) {
>>> -			vmas[i]->skip_invalidation = true;
>>> -			continue;
>>> -		}
>>> -
>>>   		/*
>>>   		 * Once purged, always purged. Cannot transition back to WILLNEED.
>>>   		 * This matches i915 semantics where purged BOs are permanently invalid.
>>> @@ -377,13 +230,14 @@ static void madvise_purgeable(struct xe_device *xe, struct xe_vm *vm,
>>>   
>>>   		switch (op->purge_state_val.val) {
>>>   		case DRM_XE_VMA_PURGEABLE_STATE_WILLNEED:
>>> -			vmas[i]->attr.purgeable_state = XE_MADV_PURGEABLE_WILLNEED;
>>>   			vmas[i]->skip_invalidation = true;
>>> -
>>> -			xe_bo_recompute_purgeable_state(bo);
>>> +			/* Only act on a real DONTNEED -> WILLNEED transition. */
>>> +			if (vmas[i]->attr.purgeable_state == XE_MADV_PURGEABLE_DONTNEED) {
>>> +				vmas[i]->attr.purgeable_state = XE_MADV_PURGEABLE_WILLNEED;
>>> +				xe_bo_willneed_get_locked(bo);
>>> +			}
>>>   			break;
>>>   		case DRM_XE_VMA_PURGEABLE_STATE_DONTNEED:
>>> -			vmas[i]->attr.purgeable_state = XE_MADV_PURGEABLE_DONTNEED;
>>>   			/*
>>>   			 * Don't zap PTEs at DONTNEED time -- pages are still
>>>   			 * alive. The zap happens in xe_bo_move_notify() right
>>> @@ -391,7 +245,11 @@ static void madvise_purgeable(struct xe_device *xe, struct xe_vm *vm,
>>>   			 */
>>>   			vmas[i]->skip_invalidation = true;
>>>   
>>> -			xe_bo_recompute_purgeable_state(bo);
>>> +			/* Only act on a real WILLNEED -> DONTNEED transition. */
>>> +			if (vmas[i]->attr.purgeable_state == XE_MADV_PURGEABLE_WILLNEED) {
>>> +				vmas[i]->attr.purgeable_state = XE_MADV_PURGEABLE_DONTNEED;
>>> +				xe_bo_willneed_put_locked(bo);
>>> +			}
>>>   			break;
>>>   		default:
>>>   			/* Should never hit - values validated in madvise_args_are_sane() */
>>> diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.h b/drivers/gpu/drm/xe/xe_vm_madvise.h
>>> index 39acd2689ca0..a3078f634c7e 100644
>>> --- a/drivers/gpu/drm/xe/xe_vm_madvise.h
>>> +++ b/drivers/gpu/drm/xe/xe_vm_madvise.h
>>> @@ -13,6 +13,4 @@ struct xe_bo;
>>>   int xe_vm_madvise_ioctl(struct drm_device *dev, void *data,
>>>   			struct drm_file *file);
>>>   
>>> -void xe_bo_recompute_purgeable_state(struct xe_bo *bo);
>>> -
>>>   #endif
>>> -- 
>>> 2.43.0
>>>

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