linux-kernel - Re: [PATCH v1 2/9] mm/mmap: Abstract vma clean up from exit

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Message-ID: <e58b16ea-3018-434e-9eff-eb6cdeef4429@redhat.com>
Date: Thu, 11 Sep 2025 11:21:03 +0200
From: David Hildenbrand <david@...hat.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: maple-tree@...ts.infradead.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Lorenzo Stoakes <lorenzo.stoakes@...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>,
 Charan Teja Kalla <quic_charante@...cinc.com>, shikemeng@...weicloud.com,
 kasong@...cent.com, nphamcs@...il.com, bhe@...hat.com, baohua@...nel.org,
 chrisl@...nel.org, Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v1 2/9] mm/mmap: Abstract vma clean up from exit_mmap()

On 09.09.25 21:09, Liam R. Howlett wrote:
> Create the new function tear_down_vmas() to remove a range of vmas.
> exit_mmap() will be removing all the vmas.
> 
> This is necessary for future patches.
> 
> No functional changes intended.
> 
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> ---
>   mm/mmap.c | 37 ++++++++++++++++++++++++-------------
>   1 file changed, 24 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index b07b3ec5e28f5..a290448a53bb2 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1250,6 +1250,29 @@ int vm_brk_flags(unsigned long addr, unsigned long request, vm_flags_t vm_flags)
>   }
>   EXPORT_SYMBOL(vm_brk_flags);
>   
> +static inline
> +unsigned long tear_down_vmas(struct mm_struct *mm, struct vma_iterator *vmi,
> +		struct vm_area_struct *vma, unsigned long max)
> +{
> +	unsigned long nr_accounted = 0;
> +	int count = 0;
> +
> +	mmap_assert_write_locked(mm);
> +	vma_iter_set(vmi, vma->vm_end);
> +	do {
> +		if (vma->vm_flags & VM_ACCOUNT)
> +			nr_accounted += vma_pages(vma);
> +		vma_mark_detached(vma);
> +		remove_vma(vma);
> +		count++;
> +		cond_resched();
> +		vma = vma_next(vmi);
> +	} while (vma && vma->vm_end <= max);
> +
> +	WARN_ON_ONCE(count != mm->map_count);

I would just do a VM_WARN_ON_ONCE() here.

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb