linux-kernel - Re: [PATCH v3 09/10] mm/vmalloc: Update __vmalloc_node

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Message-ID: <aOCejd0aghFS8iSO@MiWiFi-R3L-srv>
Date: Sat, 4 Oct 2025 12:11:57 +0800
From: Baoquan He <bhe@...hat.com>
To: "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v3 09/10] mm/vmalloc: Update __vmalloc_node_range()
 documentation

On 10/01/25 at 09:26pm, Uladzislau Rezki (Sony) wrote:
> __vmalloc() function now supports non-blocking flags such as
> GFP_ATOMIC and GFP_NOWAIT. Update the documentation accordingly.
> 
> Acked-by: Michal Hocko <mhocko@...e.com>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  mm/vmalloc.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index d7e7049e01f8..2b45cd4ce119 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -3881,19 +3881,20 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
>   * @caller:		  caller's return address
>   *
>   * Allocate enough pages to cover @size from the page level
> - * allocator with @gfp_mask flags. Please note that the full set of gfp
> - * flags are not supported. GFP_KERNEL, GFP_NOFS and GFP_NOIO are all
> - * supported.
> - * Zone modifiers are not supported. From the reclaim modifiers
> - * __GFP_DIRECT_RECLAIM is required (aka GFP_NOWAIT is not supported)
> - * and only __GFP_NOFAIL is supported (i.e. __GFP_NORETRY and
> - * __GFP_RETRY_MAYFAIL are not supported).
> + * allocator with @gfp_mask flags and map them into contiguous
> + * virtual range with protection @prot.
>   *
> - * __GFP_NOWARN can be used to suppress failures messages.
> + * Supported GFP classes: %GFP_KERNEL, %GFP_ATOMIC, %GFP_NOWAIT,
> + * %GFP_NOFS and %GFP_NOIO. Zone modifiers are not supported.
> + * Please note %GFP_ATOMIC and %GFP_NOWAIT are supported only
> + * by __vmalloc().
> +
> + * Retry modifiers: only %__GFP_NOFAIL is supported; %__GFP_NORETRY
> + * and %__GFP_RETRY_MAYFAIL are not supported.

Do we need to update the documentation of __vmalloc_node_noprof()
accordingly? I see it has below description about "Retry modifiers"
where gfp_mask is passed down to __vmalloc_node_range_noprof() directly
but have different description. Not sure if I missed anything.

===
 * Retry modifiers: only %__GFP_NOFAIL is supported; %__GFP_NORETRY
 * and %__GFP_RETRY_MAYFAIL are not supported.
===

>   *
> - * Map them into contiguous kernel virtual space, using a pagetable
> - * protection of @prot.
> + * %__GFP_NOWARN can be used to suppress failure messages.
>   *
> + * Can not be called from interrupt nor NMI contexts.
>   * Return: the address of the area or %NULL on failure
>   */
>  void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> -- 
> 2.47.3
>