From 0abdd7a81b7e3fd781d7fabcca49501852bba17e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 21 Jan 2014 15:48:12 -0800 Subject: 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 Cc: Joerg Roedel Cc: Vinod Koul Cc: Russell King Cc: James Bottomley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 6768ce9e57d2..e9c550484ba6 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -59,6 +59,7 @@ #include #include #include +#include #include #include @@ -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 -- cgit v1.2.1