Commit 9ca14f94 authored by Niranjana Vishwanathapura's avatar Niranjana Vishwanathapura Committed by Rodrigo Vivi
Browse files

drm/xe: Handle -EDEADLK case in preempt worker 



With multiple active VMs, under memory pressure, it is possible that
ttm_bo_validate() run into -EDEADLK in ttm_mem_evict_wait_busy() and
return -ENOMEM.

Until ttm properly handles locking in such scenarios, best thing the
driver can do is unwind the lock and retry.

Update preempt worker to retry validating BOs with a timeout upon
-ENOMEM.

v2: revert retry timeout upon -EAGAIN (Thomas)

Reviewed-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: default avatarNiranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent e3e4964d

drivers/gpu/drm/xe/xe_vm.c

+22 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <drm/ttm/ttm_execbuf_util.h>

#include <drm/ttm/ttm_tt.h>

#include <drm/xe_drm.h>

#include <linux/delay.h>

#include <linux/kthread.h>

#include <linux/mm.h>

#include <linux/swap.h>
@@ -508,6 +509,8 @@ void xe_vm_unlock_dma_resv(struct xe_vm *vm, 
		kvfree(tv);

}



#define XE_VM_REBIND_RETRY_TIMEOUT_MS 1000



static void preempt_rebind_work_func(struct work_struct *w)

{

	struct xe_vm *vm = container_of(w, struct xe_vm, preempt.rebind_work);
@@ -519,6 +522,7 @@ static void preempt_rebind_work_func(struct work_struct *w) 
	struct dma_fence *rebind_fence;

	unsigned int fence_count = 0;

	LIST_HEAD(preempt_fences);

	ktime_t end = 0;

	int err;

	long wait;

	int __maybe_unused tries = 0;
@@ -637,6 +641,24 @@ static void preempt_rebind_work_func(struct work_struct *w) 
		trace_xe_vm_rebind_worker_retry(vm);

		goto retry;

	}



	/*

	 * With multiple active VMs, under memory pressure, it is possible that

	 * ttm_bo_validate() run into -EDEADLK and in such case returns -ENOMEM.

	 * Until ttm properly handles locking in such scenarios, best thing the

	 * driver can do is retry with a timeout. Killing the VM or putting it

	 * in error state after timeout or other error scenarios is still TBD.

	 */

	if (err == -ENOMEM) {

		ktime_t cur = ktime_get();



		end = end ? : ktime_add_ms(cur, XE_VM_REBIND_RETRY_TIMEOUT_MS);

		if (ktime_before(cur, end)) {

			msleep(20);

			trace_xe_vm_rebind_worker_retry(vm);

			goto retry;

		}

	}

	up_write(&vm->lock);



	free_preempt_fences(&preempt_fences);