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Subject[PATCH] Fix 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 ‘grab_swap_token’:
mm/thrash.c:52: warning: comparison of unsigned expression < 0 is always false

Field token_priority is unsigned, so decrementing first and the checking
is not a good plan. Attached patch (compile tested) reverses the order.

Btw, I'm not sure if likely() makes any sense in this new situation.

Signed-off-by: Mika Kukkonen <mikukkon@iki.fi>

diff --git a/mm/thrash.c b/mm/thrash.c
index 9ef9071..c4c5205 100644
--- a/mm/thrash.c
+++ b/mm/thrash.c
@@ -48,9 +48,8 @@ void grab_swap_token(void)
if (current_interval < current->mm->last_interval)
current->mm->token_priority++;
else {
- current->mm->token_priority--;
- if (unlikely(current->mm->token_priority < 0))
- current->mm->token_priority = 0;
+ if (likely(current->mm->token_priority > 0))
+ current->mm->token_priority--;
}
/* Check if we deserve the token */
if (current->mm->token_priority >
-
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