The patch titled
Subject: lib/dma-debug.c: fix incorrect pfn calculation
has been added to the -mm tree. Its filename is
dma-debug-fix-incorrect-pfn-calculation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dma-debug-fix-incorrect-pfn-calculation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dma-debug-fix-incorrect-pfn-calculation.patch
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------------------------------------------------------
From: Miles Chen <miles.chen@xxxxxxxxxxxx>
Subject: lib/dma-debug.c: fix incorrect pfn calculation
dma-debug reports the following warning:
[name:panic&]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:
[<ffffff800808acd0>] dump_backtrace+0x0/0x1d4
[<ffffff800808affc>] show_stack+0x14/0x1c
[<ffffff800838019c>] dump_stack+0xa8/0xe0
[<ffffff80080a0594>] warn_slowpath_common+0xf4/0x11c
[<ffffff80080a061c>] warn_slowpath_fmt+0x60/0x80
[<ffffff80083afe24>] debug_dma_assert_idle+0x1a8/0x230
[<ffffff80081dca9c>] wp_page_copy.isra.96+0x118/0x520
[<ffffff80081de114>] do_wp_page+0x4fc/0x534
[<ffffff80081e0a14>] handle_mm_fault+0xd4c/0x1310
[<ffffff8008098798>] do_page_fault+0x1c8/0x394
[<ffffff800808231c>] 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.
Link: http://lkml.kernel.org/r/1506484087-1177-1-git-send-email-miles.chen@xxxxxxxxxxxx
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/dma-debug.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN lib/dma-debug.c~dma-debug-fix-incorrect-pfn-calculation lib/dma-debug.c
--- a/lib/dma-debug.c~dma-debug-fix-incorrect-pfn-calculation
+++ a/lib/dma-debug.c
@@ -1497,7 +1497,8 @@ void debug_dma_alloc_coherent(struct dev
entry->type = dma_debug_coherent;
entry->dev = dev;
- entry->pfn = page_to_pfn(virt_to_page(virt));
+ entry->pfn = is_vmalloc_addr(virt) ? vmalloc_to_pfn(virt) :
+ page_to_pfn(virt_to_page(virt));
entry->offset = offset_in_page(virt);
entry->size = size;
entry->dev_addr = dma_addr;
@@ -1513,7 +1514,8 @@ void debug_dma_free_coherent(struct devi
struct dma_debug_entry ref = {
.type = dma_debug_coherent,
.dev = dev,
- .pfn = page_to_pfn(virt_to_page(virt)),
+ .pfn = is_vmalloc_addr(virt) ? vmalloc_to_pfn(virt) :
+ page_to_pfn(virt_to_page(virt)),
.offset = offset_in_page(virt),
.dev_addr = addr,
.size = size,
_
Patches currently in -mm which might be from miles.chen@xxxxxxxxxxxx are
dma-debug-fix-incorrect-pfn-calculation.patch
checkpatch-support-function-pointers-for-unnamed-function-definition-arguments.patch
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