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author | Alex Sierra <alex.sierra@amd.com> | 2021-10-29 13:30:40 -0500 |
---|---|---|
committer | Alex Deucher <alexander.deucher@amd.com> | 2021-11-05 14:10:58 -0400 |
commit | a6283010e2907a5576f96b839e1a1c82659f137c (patch) | |
tree | 91350b0345f7beb39849c6e8b3d289237eae1216 /drivers/gpu/drm/amd/amdkfd/kfd_svm.c | |
parent | 25a1a08fe79be6ef00e1393b1f5545f6ba62919f (diff) | |
download | linux-next-a6283010e2907a5576f96b839e1a1c82659f137c.tar.gz |
drm/amdkfd: avoid recursive lock in migrations back to RAM
[Why]:
When we call hmm_range_fault to map memory after a migration, we don't
expect memory to be migrated again as a result of hmm_range_fault. The
driver ensures that all memory is in GPU-accessible locations so that
no migration should be needed. However, there is one corner case where
hmm_range_fault can unexpectedly cause a migration from DEVICE_PRIVATE
back to system memory due to a write-fault when a system memory page in
the same range was mapped read-only (e.g. COW). Ranges with individual
pages in different locations are usually the result of failed page
migrations (e.g. page lock contention). The unexpected migration back
to system memory causes a deadlock from recursive locking in our
driver.
[How]:
Creating a task reference new member under svm_range_list struct.
Setting this with "current" reference, right before the hmm_range_fault
is called. This member is checked against "current" reference at
svm_migrate_to_ram callback function. If equal, the migration will be
ignored.
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu/drm/amd/amdkfd/kfd_svm.c')
-rw-r--r-- | drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index a2000a12bed4..381d8d27a55a 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -1496,9 +1496,11 @@ static int svm_range_validate_and_map(struct mm_struct *mm, next = min(vma->vm_end, end); npages = (next - addr) >> PAGE_SHIFT; + WRITE_ONCE(p->svms.faulting_task, current); r = amdgpu_hmm_range_get_pages(&prange->notifier, mm, NULL, addr, npages, &hmm_range, readonly, true, owner); + WRITE_ONCE(p->svms.faulting_task, NULL); if (r) { pr_debug("failed %d to get svm range pages\n", r); goto unreserve_out; |