[PATCH] drm/amdkfd: Fixed kfd_process cleanup on module exit.

[David Belanger]

Handle case when module is unloaded (kfd_exit) before a process space
(mm_struct) is released.

Signed-off-by: David Belanger <david.belanger at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_module.c  |  4 ++
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 57 ++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
index 09b966dc3768..8ef4bd9e4f7d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
@@ -26,6 +26,9 @@
 #include "kfd_priv.h"
 #include "amdgpu_amdkfd.h"
 
+void kfd_cleanup_processes(void);
+
+
 static int kfd_init(void)
 {
 	int err;
@@ -77,6 +80,7 @@ static int kfd_init(void)
 
 static void kfd_exit(void)
 {
+	kfd_cleanup_processes();
 	kfd_debugfs_fini();
 	kfd_process_destroy_wq();
 	kfd_procfs_shutdown();
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index ebabe92f7edb..b5b28a32639d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -1181,6 +1181,17 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn,
 		return;
 
 	mutex_lock(&kfd_processes_mutex);
+	/*
+	 * Do early return if p is not in the table.
+	 *
+	 * This could potentially happen if this function is called concurrently
+	 * by mmu_notifier and by kfd_cleanup_pocesses.
+	 *
+	 */
+	if (!hash_hashed(&p->kfd_processes)) {
+		mutex_unlock(&kfd_processes_mutex);
+		return;
+	}
 	hash_del_rcu(&p->kfd_processes);
 	mutex_unlock(&kfd_processes_mutex);
 	synchronize_srcu(&kfd_processes_srcu);
@@ -1200,6 +1211,52 @@ static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = {
 	.free_notifier = kfd_process_free_notifier,
 };
 
+
+void kfd_cleanup_processes(void)
+{
+	struct kfd_process *p;
+	unsigned int temp;
+
+	/*
+	 * Iterate over remaining processes in table, calling notifier release
+	 * to free up notifier and process resources.
+	 *
+	 * This code handles the case when driver is unloaded before all mm_struct
+	 * are released.
+	 */
+	int idx = srcu_read_lock(&kfd_processes_srcu);
+
+	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
+		if (p) {
+			/*
+			 * Obtain a reference on p to avoid a late mmu_notifier release
+			 * call triggering freeing the process.
+			 */
+
+			kref_get(&p->ref);
+
+			srcu_read_unlock(&kfd_processes_srcu, idx);
+
+			kfd_process_notifier_release(&p->mmu_notifier, p->mm);
+
+			kfd_unref_process(p);
+
+			idx = srcu_read_lock(&kfd_processes_srcu);
+		}
+	}
+	srcu_read_unlock(&kfd_processes_srcu, idx);
+
+	/*
+	 * Must be called after all mmu_notifier_put are done and before
+	 * kfd_process_wq is released.
+	 *
+	 * Ensures that all outstanding free_notifier gets called, triggering the release
+	 * of the process.
+	 */
+	mmu_notifier_synchronize();
+}
+
+
 static int kfd_process_init_cwsr_apu(struct kfd_process *p, struct file *filep)
 {
 	unsigned long  offset;
-- 
2.38.1