On Tue, Sep 29, 2015 at 11:13:27AM +0100, Mel Gorman wrote: > On Sun, Sep 27, 2015 at 09:04:16PM +0000, Alexandru Moise wrote: > > Their stored values come from zone_page_state() which returns > > an unsigned long. To improve code correctness we should avoid > > mixing signed and unsigned integers. > > > > Signed-off-by: Alexandru Moise <00moses.alexander00@xxxxxxxxx> > > --- > > mm/page_alloc.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 48aaf7b..f55e3a2 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -2242,7 +2242,7 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order, > > /* free_pages may go negative - that's OK */ > > long min = mark; > > int o; > > - long free_cma = 0; > > + unsigned long free_cma = 0; > > > > NAK. > > free_cma is used with free_pages which is explicitly commented as saying > it can go negative. With your patch, there is a signed/unsigned operation > where the unsigned type cannot fit into the signed type which casts them > both to unsigned which is then broken for the comparison. This patch > looks broken for very subtle reasons. Please do not do any similar style > patches to this because they can introduce subtle breakage if issues are > not caught at review. > Understood, I thought the comment only applied to the "min" variable. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>