On Tue, 10 May 2022 19:38:08 +0800 Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
> We expect no warnings to be issued when we specify __GFP_NOWARN, but
> currently in paths like alloc_pages() and kmalloc(), there are still
> some warnings printed, fix it.
Looks sane to me.
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -35,6 +35,17 @@ struct folio_batch;
> /* Do not use these with a slab allocator */
> #define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
>
> +#define WARN_ON_ONCE_GFP(cond, gfp) ({ \
> + static bool __section(".data.once") __warned; \
> + int __ret_warn_once = !!(cond); \
> + \
> + if (unlikely(!(gfp & __GFP_NOWARN) && __ret_warn_once && !__warned)) { \
> + __warned = true; \
> + WARN_ON(1); \
> + } \
> + unlikely(__ret_warn_once); \
> +})
I don't think WARN_ON_ONCE_GFP is a good name for this. But
WARN_ON_ONCE_IF_NOT_GFP_NOWARN is too long :(
WARN_ON_ONCE_NOWARN might be better. No strong opinion here, really.
> @@ -4902,8 +4906,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> * We also sanity check to catch abuse of atomic reserves being used by
> * callers that are not in atomic context.
> */
> - if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
> - (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
> + if (WARN_ON_ONCE_GFP((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
> + (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM), gfp_mask))
> gfp_mask &= ~__GFP_ATOMIC;
>
> retry_cpuset:
I dropped this hunk - Neil's "mm: discard __GFP_ATOMIC"
(https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@xxxxxxxxxxxxxxxxxxxxx)
deleted this code.
