* [PATCH V1] accel/amdxdna: Fix unexpected wait when flushing notifier_wq
@ 2026-08-12 21:44 Lizhi Hou
2026-08-12 23:12 ` Max Zhen
0 siblings, 1 reply; 2+ messages in thread
From: Lizhi Hou @ 2026-08-12 21:44 UTC (permalink / raw)
To: ogabbay, quic_jhugo, dri-devel, mario.limonciello, karol.wachowski
Cc: Lizhi Hou, linux-kernel, max.zhen, sonal.santan
In amdxdna_gem_obj_free(), flush_workqueue(xdna->notifier_wq) waits for
all pending work items on the device-global notifier workqueue, rather
than only the work items associated with the BO being freed.
If another BO has a pending hmm_unreg_work, freeing an unrelated BO can
be unnecessarily blocked until that work completes.
mmu_interval_notifier_remove() is deferred to a workqueue because it
cannot be called from the MMU notifier callback itself. The BO free path
is not a notifier callback, so call mmu_interval_notifier_remove()
directly there and avoid the workqueue.
Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
---
drivers/accel/amdxdna/amdxdna_gem.c | 60 +++++++++++++++++++----------
drivers/accel/amdxdna/amdxdna_gem.h | 1 +
2 files changed, 41 insertions(+), 20 deletions(-)
diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
index 1c63eff0a4a8..d6aa862e2d5b 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.c
+++ b/drivers/accel/amdxdna/amdxdna_gem.c
@@ -301,33 +301,40 @@ static void amdxdna_hmm_unregister(struct amdxdna_gem_obj *abo,
down_write(&xdna->notifier_lock);
list_for_each_entry(mapp, &abo->mem.umap_list, node) {
- if (!vma || compare_range(mapp, vma->vm_mm, vma->vm_start, vma->vm_end)) {
- if (!mapp->unmapped) {
- queue_work(xdna->notifier_wq, &mapp->hmm_unreg_work);
- mapp->unmapped = true;
- }
- if (vma)
- break;
- }
+ if (!compare_range(mapp, vma->vm_mm, vma->vm_start, vma->vm_end))
+ continue;
+
+ queue_work(xdna->notifier_wq, &mapp->hmm_unreg_work);
+ mapp->unmapped = true;
}
up_write(&xdna->notifier_lock);
}
-static void amdxdna_umap_release(struct kref *ref)
+static void amdxdna_hmm_unregister_all(struct amdxdna_gem_obj *abo)
{
- struct amdxdna_umap *mapp = container_of(ref, struct amdxdna_umap, refcnt);
- struct amdxdna_gem_obj *abo = mapp->abo;
- struct amdxdna_dev *xdna;
-
- mmu_interval_notifier_remove(&mapp->notifier);
+ struct amdxdna_dev *xdna = to_xdna_dev(to_gobj(abo)->dev);
+ struct amdxdna_umap *mapp, *tmp;
+ LIST_HEAD(dead);
- xdna = to_xdna_dev(to_gobj(mapp->abo)->dev);
down_write(&xdna->notifier_lock);
- list_del(&mapp->node);
- if (list_empty(&abo->mem.umap_list))
- abo->mem.uva = AMDXDNA_INVALID_ADDR;
+ list_for_each_entry_safe(mapp, tmp, &abo->mem.umap_list, node) {
+ mapp->unmapped = true;
+ mapp->cleanup = true;
+ list_move(&mapp->node, &dead);
+ }
up_write(&xdna->notifier_lock);
+ list_for_each_entry_safe(mapp, tmp, &dead, node) {
+ cancel_work_sync(&mapp->hmm_unreg_work);
+ amdxdna_umap_put(mapp);
+ }
+}
+
+static void amdxdna_umap_release(struct kref *ref)
+{
+ struct amdxdna_umap *mapp = container_of(ref, struct amdxdna_umap, refcnt);
+
+ mmu_interval_notifier_remove(&mapp->notifier);
kvfree(mapp->range.hmm_pfns);
kfree(mapp);
}
@@ -341,6 +348,20 @@ static void amdxdna_hmm_unreg_work(struct work_struct *work)
{
struct amdxdna_umap *mapp = container_of(work, struct amdxdna_umap,
hmm_unreg_work);
+ struct amdxdna_gem_obj *abo = mapp->abo;
+ struct amdxdna_dev *xdna;
+
+ xdna = to_xdna_dev(to_gobj(mapp->abo)->dev);
+ down_write(&xdna->notifier_lock);
+ if (mapp->cleanup) {
+ up_write(&xdna->notifier_lock);
+ return;
+ }
+
+ list_del(&mapp->node);
+ if (list_empty(&abo->mem.umap_list))
+ abo->mem.uva = AMDXDNA_INVALID_ADDR;
+ up_write(&xdna->notifier_lock);
amdxdna_umap_put(mapp);
}
@@ -643,8 +664,7 @@ static void amdxdna_gem_obj_free(struct drm_gem_object *gobj)
struct amdxdna_dev *xdna = to_xdna_dev(gobj->dev);
struct amdxdna_gem_obj *abo = to_xdna_obj(gobj);
- amdxdna_hmm_unregister(abo, NULL);
- flush_workqueue(xdna->notifier_wq);
+ amdxdna_hmm_unregister_all(abo);
if (abo->pinned)
amdxdna_gem_unpin(abo);
diff --git a/drivers/accel/amdxdna/amdxdna_gem.h b/drivers/accel/amdxdna/amdxdna_gem.h
index 1e90e32bf3cd..fb033ced1045 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.h
+++ b/drivers/accel/amdxdna/amdxdna_gem.h
@@ -20,6 +20,7 @@ struct amdxdna_umap {
struct kref refcnt;
bool invalid;
bool unmapped;
+ bool cleanup;
};
struct amdxdna_mem {
--
2.34.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH V1] accel/amdxdna: Fix unexpected wait when flushing notifier_wq
2026-08-12 21:44 [PATCH V1] accel/amdxdna: Fix unexpected wait when flushing notifier_wq Lizhi Hou
@ 2026-08-12 23:12 ` Max Zhen
0 siblings, 0 replies; 2+ messages in thread
From: Max Zhen @ 2026-08-12 23:12 UTC (permalink / raw)
To: Lizhi Hou, ogabbay, quic_jhugo, dri-devel, mario.limonciello,
karol.wachowski
Cc: linux-kernel, sonal.santan
On 8/12/2026 Wed 14:44, Lizhi Hou wrote:
> In amdxdna_gem_obj_free(), flush_workqueue(xdna->notifier_wq) waits for
> all pending work items on the device-global notifier workqueue, rather
> than only the work items associated with the BO being freed.
>
> If another BO has a pending hmm_unreg_work, freeing an unrelated BO can
> be unnecessarily blocked until that work completes.
>
> mmu_interval_notifier_remove() is deferred to a workqueue because it
> cannot be called from the MMU notifier callback itself. The BO free path
> is not a notifier callback, so call mmu_interval_notifier_remove()
> directly there and avoid the workqueue.
>
> Fixes: e486147c912f ("accel/amdxdna: Add BO import and export")
> Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Reviewed-by: Max Zhen <max.zhen@amd.com>
> ---
> drivers/accel/amdxdna/amdxdna_gem.c | 60 +++++++++++++++++++----------
> drivers/accel/amdxdna/amdxdna_gem.h | 1 +
> 2 files changed, 41 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
> index 1c63eff0a4a8..d6aa862e2d5b 100644
> --- a/drivers/accel/amdxdna/amdxdna_gem.c
> +++ b/drivers/accel/amdxdna/amdxdna_gem.c
> @@ -301,33 +301,40 @@ static void amdxdna_hmm_unregister(struct amdxdna_gem_obj *abo,
>
> down_write(&xdna->notifier_lock);
> list_for_each_entry(mapp, &abo->mem.umap_list, node) {
> - if (!vma || compare_range(mapp, vma->vm_mm, vma->vm_start, vma->vm_end)) {
> - if (!mapp->unmapped) {
> - queue_work(xdna->notifier_wq, &mapp->hmm_unreg_work);
> - mapp->unmapped = true;
> - }
> - if (vma)
> - break;
> - }
> + if (!compare_range(mapp, vma->vm_mm, vma->vm_start, vma->vm_end))
> + continue;
> +
> + queue_work(xdna->notifier_wq, &mapp->hmm_unreg_work);
> + mapp->unmapped = true;
> }
> up_write(&xdna->notifier_lock);
> }
>
> -static void amdxdna_umap_release(struct kref *ref)
> +static void amdxdna_hmm_unregister_all(struct amdxdna_gem_obj *abo)
> {
> - struct amdxdna_umap *mapp = container_of(ref, struct amdxdna_umap, refcnt);
> - struct amdxdna_gem_obj *abo = mapp->abo;
> - struct amdxdna_dev *xdna;
> -
> - mmu_interval_notifier_remove(&mapp->notifier);
> + struct amdxdna_dev *xdna = to_xdna_dev(to_gobj(abo)->dev);
> + struct amdxdna_umap *mapp, *tmp;
> + LIST_HEAD(dead);
>
> - xdna = to_xdna_dev(to_gobj(mapp->abo)->dev);
> down_write(&xdna->notifier_lock);
> - list_del(&mapp->node);
> - if (list_empty(&abo->mem.umap_list))
> - abo->mem.uva = AMDXDNA_INVALID_ADDR;
> + list_for_each_entry_safe(mapp, tmp, &abo->mem.umap_list, node) {
> + mapp->unmapped = true;
> + mapp->cleanup = true;
> + list_move(&mapp->node, &dead);
> + }
> up_write(&xdna->notifier_lock);
>
> + list_for_each_entry_safe(mapp, tmp, &dead, node) {
> + cancel_work_sync(&mapp->hmm_unreg_work);
> + amdxdna_umap_put(mapp);
> + }
> +}
> +
> +static void amdxdna_umap_release(struct kref *ref)
> +{
> + struct amdxdna_umap *mapp = container_of(ref, struct amdxdna_umap, refcnt);
> +
> + mmu_interval_notifier_remove(&mapp->notifier);
> kvfree(mapp->range.hmm_pfns);
> kfree(mapp);
> }
> @@ -341,6 +348,20 @@ static void amdxdna_hmm_unreg_work(struct work_struct *work)
> {
> struct amdxdna_umap *mapp = container_of(work, struct amdxdna_umap,
> hmm_unreg_work);
> + struct amdxdna_gem_obj *abo = mapp->abo;
> + struct amdxdna_dev *xdna;
> +
> + xdna = to_xdna_dev(to_gobj(mapp->abo)->dev);
> + down_write(&xdna->notifier_lock);
> + if (mapp->cleanup) {
> + up_write(&xdna->notifier_lock);
> + return;
> + }
> +
> + list_del(&mapp->node);
> + if (list_empty(&abo->mem.umap_list))
> + abo->mem.uva = AMDXDNA_INVALID_ADDR;
> + up_write(&xdna->notifier_lock);
>
> amdxdna_umap_put(mapp);
> }
> @@ -643,8 +664,7 @@ static void amdxdna_gem_obj_free(struct drm_gem_object *gobj)
> struct amdxdna_dev *xdna = to_xdna_dev(gobj->dev);
> struct amdxdna_gem_obj *abo = to_xdna_obj(gobj);
>
> - amdxdna_hmm_unregister(abo, NULL);
> - flush_workqueue(xdna->notifier_wq);
> + amdxdna_hmm_unregister_all(abo);
>
> if (abo->pinned)
> amdxdna_gem_unpin(abo);
> diff --git a/drivers/accel/amdxdna/amdxdna_gem.h b/drivers/accel/amdxdna/amdxdna_gem.h
> index 1e90e32bf3cd..fb033ced1045 100644
> --- a/drivers/accel/amdxdna/amdxdna_gem.h
> +++ b/drivers/accel/amdxdna/amdxdna_gem.h
> @@ -20,6 +20,7 @@ struct amdxdna_umap {
> struct kref refcnt;
> bool invalid;
> bool unmapped;
> + bool cleanup;
> };
>
> struct amdxdna_mem {
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-08-12 21:44 [PATCH V1] accel/amdxdna: Fix unexpected wait when flushing notifier_wq Lizhi Hou
2026-08-12 23:12 ` Max Zhen
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