[PATCH] drm/amdkfd: Fix partial migrate issue
Chen, Xiaogang
xiaogang.chen at amd.com
Tue Jan 7 00:20:25 UTC 2025
On 1/6/2025 5:50 PM, Philip Yang wrote:
>
>
> On 2025-01-02 19:06, Emily Deng wrote:
>> For partial migrate from ram to vram, the migrate->cpages is not
>> equal to migrate->npages, should use migrate->npages to check all needed
>> migrate pages which could be copied or not.
>>
>> And only need to set those pages could be migrated to migrate->dst[i], or
>> the migrate_vma_pages will migrate the wrong pages based on the migrate->dst[i].
>>
>> Signed-off-by: Emily Deng<Emily.Deng at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> index 4b275937d05e..5c96c2d425e3 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
>> @@ -278,7 +278,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct svm_range *prange,
>> struct migrate_vma *migrate, struct dma_fence **mfence,
>> dma_addr_t *scratch, uint64_t ttm_res_offset)
>> {
>> - uint64_t npages = migrate->cpages;
>> + uint64_t npages = migrate->npages;
>
> As partial migration size is based on prange granularity, by default
> 2MB, maybe always migrate->cpages equal to migrate->npages, that's why
> we didn't trigger this bug. Wondering how do you catch this bug? This
> bug will leak svm_bo too, as svm_migrate_get_vram_page reference
> counter is incorrect.
>
The commit message is somehow confusing. It is not partial migration
from page fault recovery. It is the case that migrate->cpages !=
migrate->npages after migrate_vma_setup due to some pages cannot be
moved for some reasons. For that only part of src pages can be migrated.
Ex: some system ram pages got locked by kernel. Usually this case does
not happen during normal tests.
Regards
Xiaogang
>> struct amdgpu_device *adev = node->adev;
>> struct device *dev = adev->dev;
>> struct amdgpu_res_cursor cursor;
>> @@ -299,9 +299,6 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct svm_range *prange,
>> struct page *spage;
>>
>> dst[i] = cursor.start + (j << PAGE_SHIFT);
>> - migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
>> - svm_migrate_get_vram_page(prange, migrate->dst[i]);
>> - migrate->dst[i] = migrate_pfn(migrate->dst[i]);
>>
>> spage = migrate_pfn_to_page(migrate->src[i]);
>> if (spage && !is_zone_device_page(spage)) {
>> @@ -345,6 +342,9 @@ svm_migrate_copy_to_vram(struct kfd_node *node, struct svm_range *prange,
>> } else {
>> j++;
>> }
>> + migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
>> + svm_migrate_get_vram_page(prange, migrate->dst[i]);
>> + migrate->dst[i] = migrate_pfn(migrate->dst[i]);
>
> This should move forward, to handle the corner case to migrate 1 page
> to the last page of VRAM res cursor.
>
> Please check this change, to add mpages accounting to break the loop
> earlier.
>
> - uint64_t npages = migrate->cpages;
> + uint64_t npages = migrate->npages;
> struct amdgpu_device *adev = node->adev;
> struct device *dev = adev->dev;
> struct amdgpu_res_cursor cursor;
> + uint64_t mpages = 0;
> dma_addr_t *src;
> uint64_t *dst;
> uint64_t i, j;
> @@ -295,14 +296,9 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
>
> amdgpu_res_first(prange->ttm_res, ttm_res_offset,
> npages << PAGE_SHIFT, &cursor);
> - for (i = j = 0; i < npages; i++) {
> + for (i = j = 0; i < npages && mpages < migrate->cpages; i++) {
> struct page *spage;
>
> - dst[i] = cursor.start + (j << PAGE_SHIFT);
> - migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
> - svm_migrate_get_vram_page(prange, migrate->dst[i]);
> - migrate->dst[i] = migrate_pfn(migrate->dst[i]);
> -
> spage = migrate_pfn_to_page(migrate->src[i]);
> if (spage && !is_zone_device_page(spage)) {
> src[i] = dma_map_page(dev, spage, 0, PAGE_SIZE,
> @@ -322,6 +318,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> mfence);
> if (r)
> goto out_free_vram_pages;
> + mpages += j;
> amdgpu_res_next(&cursor, (j + 1) <<
> PAGE_SHIFT);
> j = 0;
> } else {
> @@ -333,6 +330,11 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> pr_debug_ratelimited("dma mapping src to 0x%llx, pfn
> 0x%lx\n",
> src[i] >> PAGE_SHIFT,
> page_to_pfn(spage));
>
> + dst[i] = cursor.start + (j << PAGE_SHIFT);
> + migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
> + svm_migrate_get_vram_page(prange, migrate->dst[i]);
> + migrate->dst[i] = migrate_pfn(migrate->dst[i]);
> +
> if (j >= (cursor.size >> PAGE_SHIFT) - 1 && i < npages
> - 1) {
> r = svm_migrate_copy_memory_gart(adev, src + i
> - j,
> dst + i - j,
> j + 1,
> @@ -340,6 +342,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> mfence);
> if (r)
> goto out_free_vram_pages;
> + mpages += j + 1;
> amdgpu_res_next(&cursor, (j + 1) * PAGE_SIZE);
> j = 0;
> } else {
> (END)
> @@ -322,6 +318,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> mfence);
> if (r)
> goto out_free_vram_pages;
> + mpages += j;
> amdgpu_res_next(&cursor, (j + 1) <<
> PAGE_SHIFT);
> j = 0;
> } else {
> @@ -333,6 +330,11 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> pr_debug_ratelimited("dma mapping src to 0x%llx, pfn
> 0x%lx\n",
> src[i] >> PAGE_SHIFT,
> page_to_pfn(spage));
>
> + dst[i] = cursor.start + (j << PAGE_SHIFT);
> + migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
> + svm_migrate_get_vram_page(prange, migrate->dst[i]);
> + migrate->dst[i] = migrate_pfn(migrate->dst[i]);
> +
> if (j >= (cursor.size >> PAGE_SHIFT) - 1 && i < npages
> - 1) {
> r = svm_migrate_copy_memory_gart(adev, src + i
> - j,
> dst + i - j,
> j + 1,
> @@ -340,6 +342,7 @@ svm_migrate_copy_to_vram(struct kfd_node *node,
> struct svm_range *prange,
> mfence);
> if (r)
> goto out_free_vram_pages;
> + mpages += j + 1;
> amdgpu_res_next(&cursor, (j + 1) * PAGE_SIZE);
> j = 0;
> } else {
>
>> }
>>
>> r = svm_migrate_copy_memory_gart(adev, src + i - j, dst + i - j, j,
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