From mboxrd@z Thu Jan  1 00:00:00 1970
From: bob.beckett@gmail.com (Robert Beckett)
Date: Mon, 2 Jul 2012 14:57:48 +0100
Subject: arm_vmregion_alloc call
Message-ID: <CAOmFF10btho+hqFSKpkqr_QDOWbFzOTKNHJL2FsZ9BvHM7DdHQ@mail.gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hello all,

I just debugged a problem with a USB driver where it was calling
dma_alloc_coherent with a GFP_DMA32 flag.
It turned out that in __dma_alloc_remap, it clears the GFP_DMA and
GFP_HIGHMEM flags when calling arm_vmregion_alloc so that it does not
clash with the slab allocator flag requirements, but it does not clear
GFP_DMA32. The GFP_SLAB_BUG_MASK includes GFP_DMA32, so this looks
like a bug to me. Should it be clearing GFP_DMA32 as well as GFP_DMA
and GFP_HIGHMEM ?

I checked in the latest kernel.org code, and the issue is still there.

Is this a bug, or should it just be calling with GFP_DMA instead of GFP_DMA32?

For now, I am working around it by using GFP_DMA in the
dma_alloc_coherent call as we have no GFP_DMA lower limit, so GFP_DMA
and GFP_DMA32 are the same on my architecture.

Any advice appreciated,

Thanks

Bob

p.s. apologies if this sent multiple times, Im trying to work around
the mailing list "suspicious header" moderation...