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drm/amdgpu: Fix the race condition for draining retry fault

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Issue:
In the scenario where svm_range_restore_pages is called, but
svm->checkpoint_ts has not been set and the retry fault has not been
drained, svm_range_unmap_from_cpu is triggered and calls svm_range_free.
Meanwhile, svm_range_restore_pages continues execution and reaches
svm_range_from_addr. This results in a "failed to find prange..." error,
 causing the page recovery to fail.

How to fix:
Move the timestamp check code under the protection of svm->lock.

v2:
Make sure all right locks are released before go out.

v3:
Directly goto out_unlock_svms, and return -EAGAIN.

v4:
Refine code.

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Emily Deng 2025-03-06 08:40:01 +08:00 committed by Alex Deucher
parent b9e75bcb2b
commit f844732e3a
1 changed files with 17 additions and 14 deletions
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31
drivers/gpu/drm/amd/amdkfd/kfd_svm.c
View File

@ -3009,19 +3009,6 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
goto out;
}
/* check if this page fault time stamp is before svms->checkpoint_ts */
if (svms->checkpoint_ts[gpuidx] != 0) {
if (amdgpu_ih_ts_after_or_equal(ts, svms->checkpoint_ts[gpuidx])) {
pr_debug("draining retry fault, drop fault 0x%llx\n", addr);
r = 0;
goto out;
} else
/* ts is after svms->checkpoint_ts now, reset svms->checkpoint_ts
* to zero to avoid following ts wrap around give wrong comparing
*/
svms->checkpoint_ts[gpuidx] = 0;
}
if (!p->xnack_enabled) {
pr_debug("XNACK not enabled for pasid 0x%x\n", pasid);
r = -EFAULT;
@ -3041,6 +3028,21 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
mmap_read_lock(mm);
retry_write_locked:
mutex_lock(&svms->lock);
/* check if this page fault time stamp is before svms->checkpoint_ts */
if (svms->checkpoint_ts[gpuidx] != 0) {
if (amdgpu_ih_ts_after_or_equal(ts, svms->checkpoint_ts[gpuidx])) {
pr_debug("draining retry fault, drop fault 0x%llx\n", addr);
r = -EAGAIN;
goto out_unlock_svms;
} else {
/* ts is after svms->checkpoint_ts now, reset svms->checkpoint_ts
* to zero to avoid following ts wrap around give wrong comparing
*/
svms->checkpoint_ts[gpuidx] = 0;
}
}
prange = svm_range_from_addr(svms, addr, NULL);
if (!prange) {
pr_debug("failed to find prange svms 0x%p address [0x%llx]\n",
@ -3166,7 +3168,8 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
mutex_unlock(&svms->lock);
mmap_read_unlock(mm);
svm_range_count_fault(node, p, gpuidx);
if (r != -EAGAIN)
svm_range_count_fault(node, p, gpuidx);
mmput(mm);
out: