From: Mika Kukkonen Date: Fri, 11 May 2007 05:22:17 +0000 (-0700) Subject: Bug in mm/thrash.c function grab_swap_token() X-Git-Tag: v2.6.22-rc1~101 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7faaa5f0bf4db6ac4908038e2139adc46c165ff4;p=linux-2.6 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 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 Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/thrash.c b/mm/thrash.c index 9ef9071f99..c4c5205a9c 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 >