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Deferred list work takes mmap write > lock to read and clear svms->drain_pagefaults, to serialize with unmap > callback. > > Add atomic flag svms->draining_faults, if svms->draining_faults is set, > page fault handle ignore the retry fault, to speed up interrupt handling. Having both svms->drain_pagefaults and svms->draining_faults is confusing. Do we really need both? Regards,   Felix > > Signed-off-by: Philip Yang > --- > drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 1 + > drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 24 ++++++++++++++++++------ > 2 files changed, 19 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h > index 1d3f012bcd2a..4e4640b731e1 100644 > --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h > @@ -767,6 +767,7 @@ struct svm_range_list { > spinlock_t deferred_list_lock; > atomic_t evicted_ranges; > bool drain_pagefaults; > + atomic_t draining_faults; > struct delayed_work restore_work; > DECLARE_BITMAP(bitmap_supported, MAX_GPU_INSTANCE); > struct task_struct *faulting_task; > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > index 3eb0a9491755..d332462bf9d3 100644 > --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > @@ -1962,6 +1962,7 @@ void svm_range_drain_retry_fault(struct svm_range_list *svms) > > p = container_of(svms, struct kfd_process, svms); > > + atomic_set(&svms->draining_faults, 1); > for_each_set_bit(i, svms->bitmap_supported, p->n_pdds) { > pdd = p->pdds[i]; > if (!pdd) > @@ -1975,6 +1976,7 @@ void svm_range_drain_retry_fault(struct svm_range_list *svms) > flush_work(&adev->irq.ih1_work); > pr_debug("drain retry fault gpu %d svms 0x%p done\n", i, svms); > } > + atomic_set(&svms->draining_faults, 0); > } > > static void svm_range_deferred_list_work(struct work_struct *work) > @@ -2002,6 +2004,7 @@ static void svm_range_deferred_list_work(struct work_struct *work) > * mmap write lock to serialize with munmap notifiers. > */ > if (unlikely(READ_ONCE(svms->drain_pagefaults))) { > + atomic_set(&svms->draining_faults, 1); > WRITE_ONCE(svms->drain_pagefaults, false); > mmap_write_unlock(mm); > svm_range_drain_retry_fault(svms); > @@ -2049,12 +2052,6 @@ svm_range_add_list_work(struct svm_range_list *svms, struct svm_range *prange, > struct mm_struct *mm, enum svm_work_list_ops op) > { > spin_lock(&svms->deferred_list_lock); > - /* Make sure pending page faults are drained in the deferred worker > - * before the range is freed to avoid straggler interrupts on > - * unmapped memory causing "phantom faults". > - */ > - if (op == SVM_OP_UNMAP_RANGE) > - svms->drain_pagefaults = true; > /* if prange is on the deferred list */ > if (!list_empty(&prange->deferred_list)) { > pr_debug("update exist prange 0x%p work op %d\n", prange, op); > @@ -2133,6 +2130,13 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange, > pr_debug("svms 0x%p prange 0x%p [0x%lx 0x%lx] [0x%lx 0x%lx]\n", svms, > prange, prange->start, prange->last, start, last); > > + /* Make sure pending page faults are drained in the deferred worker > + * before the range is freed to avoid straggler interrupts on > + * unmapped memory causing "phantom faults". > + */ > + pr_debug("set range drain_pagefaults true\n"); > + WRITE_ONCE(svms->drain_pagefaults, true); > + > unmap_parent = start <= prange->start && last >= prange->last; > > list_for_each_entry(pchild, &prange->child_list, child_list) { > @@ -2595,6 +2599,13 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid, > mm = p->mm; > mmap_write_lock(mm); > > + if (!!atomic_read(&svms->draining_faults) || > + READ_ONCE(svms->drain_pagefaults)) { > + pr_debug("draining retry fault, drop fault 0x%llx\n", addr); > + mmap_write_downgrade(mm); > + goto out_unlock_mm; > + } > + > vma = find_vma(p->mm, addr << PAGE_SHIFT); > if (!vma || (addr << PAGE_SHIFT) < vma->vm_start) { > pr_debug("VMA not found for address 0x%llx\n", addr); > @@ -2732,6 +2743,7 @@ int svm_range_list_init(struct kfd_process *p) > mutex_init(&svms->lock); > INIT_LIST_HEAD(&svms->list); > atomic_set(&svms->evicted_ranges, 0); > + atomic_set(&svms->draining_faults, 0); > INIT_DELAYED_WORK(&svms->restore_work, svm_range_restore_work); > INIT_WORK(&svms->deferred_list_work, svm_range_deferred_list_work); > INIT_LIST_HEAD(&svms->deferred_range_list);