Commit 7faaa5f0 authored May 10, 2007 by Mika Kukkonen Committed by Linus Torvalds May 11, 2007

Bug in mm/thrash.c function grab_swap_token()



Following bug was uncovered by compiling with '-W' flag:

  CC      mm/thrash.o
mm/thrash.c: In function âgrab_swap_tokenâ:
mm/thrash.c:52: warning: comparison of unsigned expression < 0 is always false

Variable token_priority is unsigned, so decrementing first and then
checking the result does not work; fixed by reversing the test, patch
attached (compile tested only).

I am not sure if likely() makes much sense in this new situation, but
I'll let somebody else to make a decision on that.

Signed-off-by: Mika Kukkonen <mikukkon@iki.fi>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 069f11f9

mm/thrash.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -48,9 +48,8 @@ void grab_swap_token(void)
		if (current_interval < current->mm->last_interval)
		current->mm->token_priority++;
		else {
		if (likely(current->mm->token_priority > 0))
		current->mm->token_priority--;
		if (unlikely(current->mm->token_priority < 0))
		current->mm->token_priority = 0;
		}
		/* Check if we deserve the token */
		if (current->mm->token_priority >

Admin message