linux-kernel - Re: [PATCH] mm: correct type for vmalloc vm

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Message-ID: <aIi7o7hjC87H8SLM@hyeyoo>
Date: Tue, 29 Jul 2025 21:16:35 +0900
From: Harry Yoo <harry.yoo@...cle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Mike Rapoport <rppt@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
        Jann Horn <jannh@...gle.com>, Pedro Falcato <pfalcato@...e.de>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Uladzislau Rezki <urezki@...il.com>
Subject: Re: [PATCH] mm: correct type for vmalloc vm_flags fields

On Tue, Jul 29, 2025 at 09:10:50PM +0900, Harry Yoo wrote:
> On Tue, Jul 29, 2025 at 12:49:06PM +0100, Lorenzo Stoakes wrote:
> > Several functions refer to the unfortunately named 'vm_flags' field when
> > referencing vmalloc flags, which happens to be the precise same name used
> > for VMA flags.
> > 
> > As a result these were erroneously changed to use the vm_flags_t type
> > (which currently is a typedef equivalent to unsigned long).
> > 
> > Currently this has no impact, but in future when vm_flags_t changes this
> > will result in issues, so change the type to unsigned long to account for
> > this.
> > 
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> > Reported-by: Harry Yoo <harry.yoo@...cle.com>
> > Closes: https://lore.kernel.org/all/aIgSpAnU8EaIcqd9@hyeyoo/
> > ---
> 
> I see one more thing in patch 3 of the series:
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 8fcf59ba39db..248d96349fd0 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -720,7 +720,7 @@ void mark_rodata_ro(void)
> 
>  static void __init declare_vma(struct vm_struct *vma,
>  			       void *va_start, void *va_end,
> -			       unsigned long vm_flags)
> +			       vm_flags_t vm_flags)
>  {
>  	phys_addr_t pa_start = __pa_symbol(va_start);
>  	unsigned long size = va_end - va_start;
> 
> 
> With that, all looks good.

I mean, the hunk above is from patch 3 and it should be reverted too.

> "struct vm_struct *vma" makes it even more confusing by the way...
> 
> -- 
> Cheers,
> Harry / Hyeonggon
> 
> >  mm/execmem.c  | 8 ++++----
> >  mm/internal.h | 2 +-
> >  mm/nommu.c    | 2 +-
> >  3 files changed, 6 insertions(+), 6 deletions(-)