Messages in this thread Patch in this message | | | From | Vikram Mulukutla <> | Subject | [PATCH] tracing: Fix unmapping loop in tracing_mark_write | Date | Wed, 17 Dec 2014 18:50:56 -0800 |
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Commit 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce introduced an array map_pages that contains the addresses returned by kmap_atomic. However, when unmapping those pages, map_pages[0] is unmapped before map_pages[1], breaking the nesting requirement as specified in the documentation for kmap_atomic/kunmap_atomic.
This was caught by the highmem debug code present in kunmap_atomic. Fix the loop to do the unmapping properly.
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Reported-by: Lime Yang <limey@codeaurora.org> Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ab76b7b..bceed34 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4931,7 +4931,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, *fpos += written; out_unlock: - for (i = 0; i < nr_pages; i++){ + for (i = nr_pages - 1; i >= 0; i--) { kunmap_atomic(map_page[i]); put_page(pages[i]); } -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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