Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] ARM: DMA: Fix kzalloc flags in __iommu_alloc_buffer() | Date | Mon, 08 Dec 2014 11:24 +0100 |
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On Monday 08 December 2014 17:39:27 Alexandre Courbot wrote: > There doesn't seem to be any valid reason to allocate the pages array > with the same flags as the buffer itself. Doing so can eventually lead > to the following safeguard in mm/slab.c to be hit: > > BUG_ON(flags & GFP_SLAB_BUG_MASK); > > This happens when buffers are allocated with __GFP_DMA32 or > __GFP_HIGHMEM. > > Fix this by allocating the pages array with GFP_KERNEL to follow what is > done elsewhere in this file. Using GFP_KERNEL in __iommu_alloc_buffer() > is safe because atomic allocations are handled by __iommu_alloc_atomic(). >
I think you need to carry over the GFP_ATOMIC flag if that is set by the caller, but not the GFP_HIGHMEM or GFP_DMA32. Not sure if it's better to mask out flags from the caller mask, or to start with GFP_KERNEL and adding in extra bits.
Arnd
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