Restoring multiple processes concurrently can lead to live-locks
where each process prevents the other from validating all its BOs.
Signed-off-by: Felix Kuehling <felix.kuehl...@amd.com>
---
drivers/gpu/drm/amd/amdkfd/kfd_module.c | 6 +++++-
drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 2 +-
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 30 ++++++++++++++++++++++++++----
3 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
index b0acb06..e0c07d2 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
@@ -133,7 +133,9 @@ static int __init kfd_module_init(void)
if (err < 0)
goto err_topology;
- kfd_process_create_wq();
+ err = kfd_process_create_wq();
+ if (err < 0)
+ goto err_create_wq;
kfd_debugfs_init();
@@ -143,6 +145,8 @@ static int __init kfd_module_init(void)
return 0;
+err_create_wq:
+ kfd_topology_shutdown();
err_topology:
kfd_chardev_exit();
err_ioctl:
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index db27f9f..96a9cc0 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -674,7 +674,7 @@ struct amdkfd_ioctl_desc {
const char *name;
};
-void kfd_process_create_wq(void);
+int kfd_process_create_wq(void);
void kfd_process_destroy_wq(void);
struct kfd_process *kfd_create_process(struct file *filep);
struct kfd_process *kfd_get_process(const struct task_struct *);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 45ef2d0..75fdc18 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -48,8 +48,17 @@ static DEFINE_MUTEX(kfd_processes_mutex);
DEFINE_SRCU(kfd_processes_srcu);
+/* For process termination handling */
static struct workqueue_struct *kfd_process_wq;
+/* Ordered, single-threaded workqueue for restoring evicted
+ * processes. Restoring multiple processes concurrently under memory
+ * pressure can lead to processes blocking each other from validating
+ * their BOs and result in a live-lock situation where processes
+ * remain evicted indefinitely.
+ */
+static struct workqueue_struct *kfd_restore_wq;
+
static struct kfd_process *find_process(const struct task_struct *thread);
static void kfd_process_ref_release(struct kref *ref);
static struct kfd_process *create_process(const struct task_struct *thread,
@@ -59,10 +68,19 @@ static void evict_process_worker(struct work_struct *work);
static void restore_process_worker(struct work_struct *work);
-void kfd_process_create_wq(void)
+int kfd_process_create_wq(void)
{
if (!kfd_process_wq)
kfd_process_wq = alloc_workqueue("kfd_process_wq", 0, 0);
+ if (!kfd_restore_wq)
+ kfd_restore_wq = alloc_ordered_workqueue("kfd_restore_wq", 0);
+
+ if (!kfd_restore_wq || !kfd_restore_wq) {
+ kfd_process_destroy_wq();
+ return -ENOMEM;
+ }
+
+ return 0;
}
void kfd_process_destroy_wq(void)
@@ -71,6 +89,10 @@ void kfd_process_destroy_wq(void)
destroy_workqueue(kfd_process_wq);
kfd_process_wq = NULL;
}
+ if (kfd_restore_wq) {
+ destroy_workqueue(kfd_restore_wq);
+ kfd_restore_wq = NULL;
+ }
}
static void kfd_process_free_gpuvm(struct kgd_mem *mem,
@@ -869,7 +891,7 @@ static void evict_process_worker(struct work_struct *work)
dma_fence_signal(p->ef);
dma_fence_put(p->ef);
p->ef = NULL;
- schedule_delayed_work(&p->restore_work,
+ queue_delayed_work(kfd_restore_wq, &p->restore_work,
msecs_to_jiffies(PROCESS_RESTORE_TIME_MS));
pr_debug("Finished evicting pasid %d\n", p->pasid);
@@ -918,7 +940,7 @@ static void restore_process_worker(struct work_struct *work)
if (ret) {
pr_debug("Failed to restore BOs of pasid %d, retry after %d
ms\n",
p->pasid, PROCESS_BACK_OFF_TIME_MS);
- ret = schedule_delayed_work(&p->restore_work,
+ ret = queue_delayed_work(kfd_restore_wq, &p->restore_work,
msecs_to_jiffies(PROCESS_BACK_OFF_TIME_MS));
WARN(!ret, "reschedule restore work failed\n");
return;
@@ -957,7 +979,7 @@ int kfd_resume_all_processes(void)
int ret = 0, idx = srcu_read_lock(&kfd_processes_srcu);
hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
- if (!schedule_delayed_work(&p->restore_work, 0)) {
+ if (!queue_delayed_work(kfd_restore_wq, &p->restore_work, 0)) {
pr_err("Restore process %d failed during resume\n",
p->pasid);
ret = -EFAULT;
--
2.7.4
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