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drm/xe: Handle -EDEADLK case in preempt worker

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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: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Niranjana Vishwanathapura 2023-05-08 05:22:23 +00:00 committed by Rodrigo Vivi
parent e3e4964d33
commit 9ca14f94d2
1 changed files with 22 additions and 0 deletions
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22
drivers/gpu/drm/xe/xe_vm.c
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@ -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 @@ out_unlock_outer:
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);