Commit 20bc9f76 authored by David Belanger's avatar David Belanger Committed by Alex Deucher
Browse files

drm/amdkfd: Fixed kfd_process cleanup on module exit. 



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

v2: Fixed potential race conditions by removing all kfd_process from
the process table first, then working on releasing the resources.

v3: Fixed loop element access / synchronization.  Fixed extra empty lines.

Signed-off-by: default avatarDavid Belanger <david.belanger@amd.com>
Reviewed-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 7304ee97

drivers/gpu/drm/amd/amdkfd/kfd_module.c

+1 −0
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ static int kfd_init(void) 


static void kfd_exit(void)

{

	kfd_cleanup_processes();

	kfd_debugfs_fini();

	kfd_process_destroy_wq();

	kfd_procfs_shutdown();

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

+1 −0
Original line number Diff line number Diff line
@@ -928,6 +928,7 @@ bool kfd_dev_is_large_bar(struct kfd_dev *dev); 


int kfd_process_create_wq(void);

void kfd_process_destroy_wq(void);

void kfd_cleanup_processes(void);

struct kfd_process *kfd_create_process(struct file *filep);

struct kfd_process *kfd_get_process(const struct task_struct *task);

struct kfd_process *kfd_lookup_process_by_pasid(u32 pasid);

drivers/gpu/drm/amd/amdkfd/kfd_process.c

+60 −7
Original line number Diff line number Diff line
@@ -1167,6 +1167,17 @@ static void kfd_process_free_notifier(struct mmu_notifier *mn) 
	kfd_unref_process(container_of(mn, struct kfd_process, mmu_notifier));

}



static void kfd_process_notifier_release_internal(struct kfd_process *p)

{

	cancel_delayed_work_sync(&p->eviction_work);

	cancel_delayed_work_sync(&p->restore_work);



	/* Indicate to other users that MM is no longer valid */

	p->mm = NULL;



	mmu_notifier_put(&p->mmu_notifier);

}



static void kfd_process_notifier_release(struct mmu_notifier *mn,

					struct mm_struct *mm)

{
@@ -1181,17 +1192,22 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn, 
		return;



	mutex_lock(&kfd_processes_mutex);

	/*

	 * Do early return if table is empty.

	 *

	 * This could potentially happen if this function is called concurrently

	 * by mmu_notifier and by kfd_cleanup_pocesses.

	 *

	 */

	if (hash_empty(kfd_processes_table)) {

		mutex_unlock(&kfd_processes_mutex);

		return;

	}

	hash_del_rcu(&p->kfd_processes);

	mutex_unlock(&kfd_processes_mutex);

	synchronize_srcu(&kfd_processes_srcu);



	cancel_delayed_work_sync(&p->eviction_work);

	cancel_delayed_work_sync(&p->restore_work);



	/* Indicate to other users that MM is no longer valid */

	p->mm = NULL;



	mmu_notifier_put(&p->mmu_notifier);

	kfd_process_notifier_release_internal(p);

}



static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = {
@@ -1200,6 +1216,43 @@ static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = { 
	.free_notifier = kfd_process_free_notifier,

};



/*

 * This code handles the case when driver is being unloaded before all

 * mm_struct are released.  We need to safely free the kfd_process and

 * avoid race conditions with mmu_notifier that might try to free them.

 *

 */

void kfd_cleanup_processes(void)

{

	struct kfd_process *p;

	struct hlist_node *p_temp;

	unsigned int temp;

	HLIST_HEAD(cleanup_list);



	/*

	 * Move all remaining kfd_process from the process table to a

	 * temp list for processing.   Once done, callback from mmu_notifier

	 * release will not see the kfd_process in the table and do early return,

	 * avoiding double free issues.

	 */

	mutex_lock(&kfd_processes_mutex);

	hash_for_each_safe(kfd_processes_table, temp, p_temp, p, kfd_processes) {

		hash_del_rcu(&p->kfd_processes);

		synchronize_srcu(&kfd_processes_srcu);

		hlist_add_head(&p->kfd_processes, &cleanup_list);

	}

	mutex_unlock(&kfd_processes_mutex);



	hlist_for_each_entry_safe(p, p_temp, &cleanup_list, kfd_processes)

		kfd_process_notifier_release_internal(p);



	/*

	 * Ensures that all outstanding free_notifier get called, triggering

	 * the release of the kfd_process struct.

	 */

	mmu_notifier_synchronize();

}



static int kfd_process_init_cwsr_apu(struct kfd_process *p, struct file *filep)

{

	unsigned long  offset;