On Sat, 26 Oct 2013 15:36:17 +0100
Will Deacon <will.deacon@xxxxxxx> wrote:
> On Thu, Oct 24, 2013 at 09:07:30PM +0100, Aaro Koskinen wrote:
>
> > [ 36.477203] Backtrace:
> > [ 36.535603] [<c009237c>] (page_mapping+0x0/0x50) from [<c0010dd8>] (flush_kernel_dcache_page+0x14/0x98)
> > [ 36.661070] [<c0010dc4>] (flush_kernel_dcache_page+0x0/0x98) from [<c0172b60>] (sg_miter_stop+0xc8/0x10c)
> > [ 36.792813] r4:df8a9a64 r3:00000003
> > [ 36.857524] [<c0172a98>] (sg_miter_stop+0x0/0x10c) from [<c0172f20>] (sg_miter_next+0x14/0x13c)
>
> ... assumedly for scatter/gather DMA. How is your block driver allocating
> its buffers? If you're using the DMA API, I can't see how this would happen.
Lots of SCSI commands(inquiry, ...) pass kmalloc buffer to block layer,
then the sg buffer copy helpers and flush_kernel_dcache_page() may see
slab page.
That has been here from commit b1adaf65ba03( [SCSI] block: add sg buffer copy
helper functions).
So how about letting below patch to workaround the issue?
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index a685c8a..eea8806 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -577,7 +577,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
miter->__offset += miter->consumed;
miter->__remaining -= miter->consumed;
- if (miter->__flags & SG_MITER_TO_SG)
+ if ((miter->__flags & SG_MITER_TO_SG) && !PageSlab(page))
flush_kernel_dcache_page(miter->page);
if (miter->__flags & SG_MITER_ATOMIC) {
Thanks,
--
Ming Lei
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