[PATCH v2] nouveau/dmem: handle kcalloc() allocation failure

[Duoming Zhou]

The kcalloc() in nouveau_dmem_evict_chunk() will return null if
the physical memory has run out. As a result, if we dereference
src_pfns, dst_pfns or dma_addrs, the null pointer dereference bugs
will happen.

Moreover, the GPU is going away. If the kcalloc() fails, we could not
evict all pages mapping a chunk. So this patch adds a __GFP_NOFAIL
flag in kcalloc().

Fixes: 249881232e14 ("nouveau/dmem: evict device private memory during release")
Signed-off-by: Duoming Zhou <duom...@zju.edu.cn>
---
Changes in v2:
  - Allocate with __GFP_NOFAIL.

 drivers/gpu/drm/nouveau/nouveau_dmem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c 
b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 12feecf71e7..f5ae9724ee2 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -378,9 +378,9 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
        dma_addr_t *dma_addrs;
        struct nouveau_fence *fence;
 
-       src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL);
-       dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL);
-       dma_addrs = kcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL);
+       src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | 
__GFP_NOFAIL);
+       dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | 
__GFP_NOFAIL);
+       dma_addrs = kcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL | 
__GFP_NOFAIL);
 
        migrate_device_range(src_pfns, chunk->pagemap.range.start >> PAGE_SHIFT,
                        npages);
-- 
2.17.1