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authorDan Williams <dan.j.williams@intel.com>2014-01-21 15:48:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 16:19:41 -0800
commit0abdd7a81b7e3fd781d7fabcca49501852bba17e (patch)
tree20ab3aa4b476ceaf6d3a824c842cd581445ded8b /mm/memory.c
parent03d11a0e458d7008192585124e4c3313c2829046 (diff)
downloadop-kernel-dev-0abdd7a81b7e3fd781d7fabcca49501852bba17e.zip
op-kernel-dev-0abdd7a81b7e3fd781d7fabcca49501852bba17e.tar.gz
dma-debug: introduce debug_dma_assert_idle()
Record actively mapped pages and provide an api for asserting a given page is dma inactive before execution proceeds. Placing debug_dma_assert_idle() in cow_user_page() flagged the violation of the dma-api in the NET_DMA implementation (see commit 77873803363c "net_dma: mark broken"). The implementation includes the capability to count, in a limited way, repeat mappings of the same page that occur without an intervening unmap. This 'overlap' counter is limited to the few bits of tag space in a radix tree. This mechanism is added to mitigate false negative cases where, for example, a page is dma mapped twice and debug_dma_assert_idle() is called after the page is un-mapped once. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Vinod Koul <vinod.koul@intel.com> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: James Bottomley <JBottomley@Parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 6768ce9..e9c5504 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -59,6 +59,7 @@
#include <linux/gfp.h>
#include <linux/migrate.h>
#include <linux/string.h>
+#include <linux/dma-debug.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
@@ -2559,6 +2560,8 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
{
+ debug_dma_assert_idle(src);
+
/*
* If the source page was a PFN mapping, we don't have
* a "struct page" for it. We do a best-effort copy by
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