On 02/25/2016 12:43 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> 647757197cd3 ("mm: clarify __GFP_NOFAIL deprecation status") was
> incomplete and didn't remove the comment about __GFP_NOFAIL being
> deprecated in buffered_rmqueue. Let's get rid of this leftover
> but keep the WARN_ON_ONCE for order > 1 because we should really
> discourage from using __GFP_NOFAIL with higher order allocations
> because those are just too subtle.
>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> Hi,
> this popped out when discussing another patch http://lkml.kernel.org/r/56CEC568.6080809@xxxxxxxx
> so I think it is worth removing the comment.
>
> mm/page_alloc.c | 18 +++++-------------
> 1 file changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1993894b4219..109d975a7172 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2347,19 +2347,11 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
> list_del(&page->lru);
> pcp->count--;
> } else {
> - if (unlikely(gfp_flags & __GFP_NOFAIL)) {
> - /*
> - * __GFP_NOFAIL is not to be used in new code.
> - *
> - * All __GFP_NOFAIL callers should be fixed so that they
> - * properly detect and handle allocation failures.
> - *
> - * We most definitely don't want callers attempting to
> - * allocate greater than order-1 page units with
> - * __GFP_NOFAIL.
> - */
> - WARN_ON_ONCE(order > 1);
> - }
> + /*
> + * We most definitely don't want callers attempting to
> + * allocate greater than order-1 page units with __GFP_NOFAIL.
> + */
> + WARN_ON_ONCE(unlikely(gfp_flags & __GFP_NOFAIL) && (order > 1));
WARN_ON_ONCE already includes an unlikely in its definition:
http://lxr.free-electrons.com/source/include/asm-generic/bug.h#L109
> spin_lock_irqsave(&zone->lock, flags);
>
> page = NULL;
>
Reviewed-by: Nikolay Borisov <kernel@xxxxxxxx>
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