Re: [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC

[Andrew Morton]

On Tue, 18 Jul 2023 14:35:11 +0800 sunran001@xxxxxxxxxx wrote:

> ERROR: function pcpu_balance_populated called on line 2238 inside lock
> on line 2234 but uses GFP_KERNEL
> 
> Generated by: scripts/coccinelle/locks/call_kern.cocci
> 
> ...
>
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -2033,7 +2033,7 @@ static void pcpu_balance_free(bool empty_only)
>   static void pcpu_balance_populated(void)
>   {
>       /* gfp flags passed to underlying allocators */
> -    const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
> +    const gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
>       struct pcpu_chunk *chunk;
>       int slot, nr_to_pop, ret;

I don't believe this warning is correct.  

			spin_unlock_irq(&pcpu_lock);
			ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
			cond_resched();
			spin_lock_irq(&pcpu_lock);