[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.belan...@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