linux-kernel - Re: [PATCH v4 1/4] mm: cma: introduce gfp flag in cma_alloc instead of no

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Message-ID: <20210125130701.GF827@dhcp22.suse.cz>
Date:   Mon, 25 Jan 2021 14:07:01 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, hyesoo.yu@...sung.com,
        david@...hat.com, surenb@...gle.com, pullip.cho@...sung.com,
        joaodias@...gle.com, hridya@...gle.com, john.stultz@...aro.org,
        sumit.semwal@...aro.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, hch@...radead.org, robh+dt@...nel.org,
        linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH v4 1/4] mm: cma: introduce gfp flag in cma_alloc instead
 of no_warn

On Thu 21-01-21 09:54:59, Minchan Kim wrote:
> The upcoming patch will introduce __GFP_NORETRY semantic
> in alloc_contig_range which is a failfast mode of the API.
> Instead of adding a additional parameter for gfp, replace
> no_warn with gfp flag.
> 
> To keep old behaviors, it follows the rule below.
> 
>   no_warn 			gfp_flags
> 
>   false         		GFP_KERNEL
>   true          		GFP_KERNEL|__GFP_NOWARN
>   gfp & __GFP_NOWARN		GFP_KERNEL | (gfp & __GFP_NOWARN)
> 
> Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>
> Signed-off-by: Minchan Kim <minchan@...nel.org>
[...]
> diff --git a/mm/cma.c b/mm/cma.c
> index 0ba69cd16aeb..d50627686fec 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -419,13 +419,13 @@ static inline void cma_debug_show_areas(struct cma *cma) { }
>   * @cma:   Contiguous memory region for which the allocation is performed.
>   * @count: Requested number of pages.
>   * @align: Requested alignment of pages (in PAGE_SIZE order).
> - * @no_warn: Avoid printing message about failed allocation
> + * @gfp_mask: GFP mask to use during the cma allocation.

Call out supported gfp flags explicitly. Have a look at kvmalloc_node
for a guidance.
-- 
Michal Hocko
SUSE Labs