On Fri, 29 Jul 2011, KOSAKI Motohiro wrote:
> (2011/07/29 6:05), Jesper Juhl wrote:
> > We have this code in mm/vmscan.c:shrink_slab() :
> > ...
> > if (total_scan < 0) {
> > printk(KERN_ERR "shrink_slab: %pF negative objects to "
> > "delete nr=%ld\n",
> > shrinker->shrink, total_scan);
> > total_scan = max_pass;
> > }
> > ...
> > but since 'total_scan' is of type 'unsigned long' it will never be
> > less than zero, so there is no way we'll ever enter the true branch of
> > this if statement - so let's just remove it.
> >
> > Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
> > ---
> > mm/vmscan.c | 6 ------
> > 1 files changed, 0 insertions(+), 6 deletions(-)
> >
> > Compile tested only.
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 7ef6912..c07d9b1 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -271,12 +271,6 @@ unsigned long shrink_slab(struct shrink_control *shrink,
> > delta *= max_pass;
> > do_div(delta, lru_pages + 1);
> > total_scan += delta;
> > - if (total_scan < 0) {
> > - printk(KERN_ERR "shrink_slab: %pF negative objects to "
> > - "delete nr=%ld\n",
> > - shrinker->shrink, total_scan);
> > - total_scan = max_pass;
> > - }
> >
> > /*
> > * We need to avoid excessive windup on filesystem shrinkers
>
> Good catch.
>
> However this seems intended to catch a overflow. So, I'd suggest to make proper
> overflow check instead.
>
Right. We probably shouldn't just remove it.
I'll cook a new version of the patch tonight that properly checks for
overflow.
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Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
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