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lib/dma-debug.c: fix incorrect pfn calculation

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dma-debug reports the following warning:

  WARNING: CPU: 3 PID: 298 at kernel-4.4/lib/dma-debug.c:604
  debug _dma_assert_idle+0x1a8/0x230()
  DMA-API: cpu touching an active dma mapped cacheline [cln=0x00000882300]
  CPU: 3 PID: 298 Comm: vold Tainted: G        W  O    4.4.22+ #1
  Hardware name: MT6739 (DT)
  Call trace:
    debug_dma_assert_idle+0x1a8/0x230
    wp_page_copy.isra.96+0x118/0x520
    do_wp_page+0x4fc/0x534
    handle_mm_fault+0xd4c/0x1310
    do_page_fault+0x1c8/0x394
    do_mem_abort+0x50/0xec

I found that debug_dma_alloc_coherent() and debug_dma_free_coherent()
assume that dma_alloc_coherent() always returns a linear address.

However it's possible that dma_alloc_coherent() returns a non-linear
address.  In this case, page_to_pfn(virt_to_page(virt)) will return an
incorrect pfn.  If the pfn is valid and mapped as a COW page, we will
hit the warning when doing wp_page_copy().

Fix this by calculating pfn for linear and non-linear addresses.

[[email protected]: v4]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Miles Chen <[email protected]>
Reviewed-by: Robin Murphy <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Miles Chen authored and Linus Torvalds committed 2017-11-17 16:10:00 -08:00
1 parent 5d03a66139
commit 3aaabbf1c3
1 file changed
+18 -2
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lib/dma-debug.c
+18 -2
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@@ -1495,14 +1495,22 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size,
if (!entry)
return;
/* handle vmalloc and linear addresses */
if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
return;
entry->type = dma_debug_coherent;
entry->dev = dev;
entry->pfn = page_to_pfn(virt_to_page(virt));
entry->offset = offset_in_page(virt);
entry->size = size;
entry->dev_addr = dma_addr;
entry->direction = DMA_BIDIRECTIONAL;
if (is_vmalloc_addr(virt))
entry->pfn = vmalloc_to_pfn(virt);
else
entry->pfn = page_to_pfn(virt_to_page(virt));
add_dma_entry(entry);
}
EXPORT_SYMBOL(debug_dma_alloc_coherent);
@@ -1513,13 +1521,21 @@ void debug_dma_free_coherent(struct device *dev, size_t size,
struct dma_debug_entry ref = {
.type = dma_debug_coherent,
.dev = dev,
.pfn = page_to_pfn(virt_to_page(virt)),
.offset = offset_in_page(virt),
.dev_addr = addr,
.size = size,
.direction = DMA_BIDIRECTIONAL,
};
/* handle vmalloc and linear addresses */
if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
return;
if (is_vmalloc_addr(virt))
ref.pfn = vmalloc_to_pfn(virt);
else
ref.pfn = page_to_pfn(virt_to_page(virt));
if (unlikely(dma_debug_disabled()))
return;