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

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Message-ID: <aOCqSrnazd2YwGbe@MiWiFi-R3L-srv>
Date: Sat, 4 Oct 2025 13:02:02 +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 10/04/25 at 12:11pm, Baoquan He wrote:
> 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.
> ===

Sorry, I copied the wrong sentences. Below is copied from documentation
of __vmalloc_node_noprof().
====
 * Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL
 * and __GFP_NOFAIL 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
> > 
>