Several GPU SVM paths take mmap_read_lock() only to call hmm_range_fault() and open-code mmu interval sequence setup before each HMM walk. They also retry -EBUSY until HMM_RANGE_DEFAULT_TIMEOUT expires.
Use hmm_range_fault_unlocked_timeout() for those faults. The HMM helper now owns mmap_lock acquisition and refreshes range->notifier_seq for its internal retries, while GPU SVM keeps its existing driver-lock validation with mmu_interval_read_retry() after a successful fault. Pass HMM_RANGE_DEFAULT_TIMEOUT as the helper retry budget for each HMM fault attempt. This scopes the timeout to repeated HMM notifier retries while preserving the outer retry loops that restart when the interval is invalidated before GPU SVM updates or consumes the mapping state. Leave drm_gpusvm_check_pages() on hmm_range_fault() because that path is called with the mmap lock already held by its caller. Reviewed-by: Jason Gunthorpe <[email protected]> Signed-off-by: Stanislav Kinsburskii <[email protected]> --- drivers/gpu/drm/drm_gpusvm.c | 61 +++++------------------------------------- 1 file changed, 7 insertions(+), 54 deletions(-) diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c index 958cb605aedd..de5bbfe58ee9 100644 --- a/drivers/gpu/drm/drm_gpusvm.c +++ b/drivers/gpu/drm/drm_gpusvm.c @@ -773,8 +773,7 @@ enum drm_gpusvm_scan_result drm_gpusvm_scan_mm(struct drm_gpusvm_range *range, .end = end, .dev_private_owner = dev_private_owner, }; - unsigned long timeout = - jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); + unsigned long timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); enum drm_gpusvm_scan_result state = DRM_GPUSVM_SCAN_UNPOPULATED, new_state; unsigned long *pfns; unsigned long npages = npages_in_range(start, end); @@ -788,22 +787,7 @@ enum drm_gpusvm_scan_result drm_gpusvm_scan_mm(struct drm_gpusvm_range *range, hmm_range.hmm_pfns = pfns; retry: - hmm_range.notifier_seq = mmu_interval_read_begin(notifier); - mmap_read_lock(range->gpusvm->mm); - - while (true) { - err = hmm_range_fault(&hmm_range); - if (err == -EBUSY) { - if (time_after(jiffies, timeout)) - break; - - hmm_range.notifier_seq = - mmu_interval_read_begin(notifier); - continue; - } - break; - } - mmap_read_unlock(range->gpusvm->mm); + err = hmm_range_fault_unlocked_timeout(&hmm_range, timeout); if (err) goto err_free; @@ -1406,8 +1390,7 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, .dev_private_owner = ctx->device_private_page_owner, }; void *zdd; - unsigned long timeout = - jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); + unsigned long timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); unsigned long i, j; unsigned long npages = npages_in_range(pages_start, pages_end); unsigned long num_dma_mapped; @@ -1422,9 +1405,6 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, struct dma_iova_state *state = &svm_pages->state; retry: - if (time_after(jiffies, timeout)) - return -EBUSY; - hmm_range.notifier_seq = mmu_interval_read_begin(notifier); if (drm_gpusvm_pages_valid_unlocked(gpusvm, svm_pages)) goto set_seqno; @@ -1439,21 +1419,7 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, } hmm_range.hmm_pfns = pfns; - while (true) { - mmap_read_lock(mm); - err = hmm_range_fault(&hmm_range); - mmap_read_unlock(mm); - - if (err == -EBUSY) { - if (time_after(jiffies, timeout)) - break; - - hmm_range.notifier_seq = - mmu_interval_read_begin(notifier); - continue; - } - break; - } + err = hmm_range_fault_unlocked_timeout(&hmm_range, timeout); mmput(mm); if (err) goto err_free; @@ -1720,8 +1686,7 @@ int drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm, .end = drm_gpusvm_range_end(range), .dev_private_owner = NULL, }; - unsigned long timeout = - jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); + unsigned long timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); unsigned long *pfns; unsigned long npages = npages_in_range(drm_gpusvm_range_start(range), drm_gpusvm_range_end(range)); @@ -1736,24 +1701,12 @@ int drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm, return -ENOMEM; hmm_range.hmm_pfns = pfns; - while (!time_after(jiffies, timeout)) { - hmm_range.notifier_seq = mmu_interval_read_begin(notifier); - if (time_after(jiffies, timeout)) { - err = -ETIME; - break; - } - - mmap_read_lock(mm); - err = hmm_range_fault(&hmm_range); - mmap_read_unlock(mm); - if (err != -EBUSY) - break; - } + err = hmm_range_fault_unlocked_timeout(&hmm_range, timeout); kvfree(pfns); mmput(mm); - return err; + return err == -EBUSY ? -ETIME : err; } EXPORT_SYMBOL_GPL(drm_gpusvm_range_evict);
