Commit 7215853e authored Dec 17, 2014 by Vikram Mulukutla Committed by Steven Rostedt Feb 09, 2015

tracing: Fix unmapping loop in tracing_mark_write

Commit 6edb2a8a 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.

Link: http://lkml.kernel.org/r/1418871056-6614-1-git-send-email-markivx@codeaurora.org



Cc: stable@vger.kernel.org # 3.5+
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Lime Yang <limey@codeaurora.org>
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 7496946a

kernel/trace/trace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4928,7 +4928,7 @@ 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]);
		}

Admin message