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SubjectRe: [PATCH] vmscan: Remove if statement that will never trigger
(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@chaosbits.net>
> ---
> 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.




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