Messages in this thread | | | Date | Fri, 18 Mar 2016 09:05:52 +0100 | From | Rabin Vincent <> | Subject | Re: [PATCH] ARM: DMA: Fix kzalloc flags in __dma_alloc |
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On Fri, Mar 18, 2016 at 11:12:26AM +0900, Alexandre Courbot wrote: > Commit 19e6e5e5392b ("ARM: 8547/1: dma-mapping: store buffer > information") allocates a structure meant for internal buffer management > with the GFP flags of the buffer itself. This can trigger the following > safeguard in the slab/slub allocator: > > if (unlikely(flags & GFP_SLAB_BUG_MASK)) { > pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK); > BUG(); > } > > Fix this by allocating the structure with GFP_KERNEL, as it is meant to > be used by the kernel and not for DMA.
We can't use GFP_KERNEL here. The caller may have passed in gfp flags which indicate that we can't sleep, and we need to respect that. What we can do is mask out the region specifiers in the gfp flags that we pass to kzalloc(). This is what the other architectures do in their dma allocation functions:
arch/mips/cavium-octeon/dma-octeon.c: gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); arch/mips/loongson64/common/dma-swiotlb.c: gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); arch/mips/mm/dma-default.c: gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); arch/mips/netlogic/common/nlm-dma.c: gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); arch/x86/kernel/pci-dma.c: *gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
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