linux-kernel - Re: [PATCH 3/3] mm/mempool: use might

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Date:   Tue, 14 Jun 2022 15:08:34 +0200
From:   "Vlastimil Babka (SUSE)" <vbabka@...nel.org>
To:     Daniel Vetter <daniel.vetter@...ll.ch>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     DRI Development <dri-devel@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: [PATCH 3/3] mm/mempool: use might_alloc()

On 6/5/22 17:25, Daniel Vetter wrote:
> mempool are generally used for GFP_NOIO, so this wont benefit all that
> much because might_alloc currently only checks GFP_NOFS. But it does
> validate against mmu notifier pte zapping, some might catch some
> drivers doing really silly things, plus it's a bit more meaningful in
> what we're checking for here.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-mm@...ck.org

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  mm/mempool.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mempool.c b/mm/mempool.c
> index b933d0fc21b8..96488b13a1ef 100644
> --- a/mm/mempool.c
> +++ b/mm/mempool.c
> @@ -379,7 +379,7 @@ void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
>  	gfp_t gfp_temp;
>  
>  	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
> -	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
> +	might_alloc(gfp_mask);
>  
>  	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */
>  	gfp_mask |= __GFP_NORETRY;	/* don't loop in __alloc_pages */