Re: [PATCH v1 10/16] mm/memory: use __zap_vma_range() in zap_vma_for_reaping()

Lorenzo Stoakes (Oracle)
2026-03-06T12:27:32Z

On Fri, Feb 27, 2026 at 09:08:41PM +0100, David Hildenbrand (Arm) wrote:
> Let's call __zap_vma_range() instead of unmap_page_range() to prepare
> for further cleanups.
>
> To keep the existing behavior, whereby we do not call uprobe_munmap()
> which could block, add a new "reaping" member to zap_details and use it.

I am always in favour of making further use of helper structs :)

>
> Likely we should handle the possible blocking in uprobe_munmap()
> differently, but for now keep it unchanged.
>
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

OK this looks like it's doing the equivalent of what was there before, so:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

> ---
> include/linux/mm.h | 1 +
> mm/memory.c | 13 +++++++++----
> 2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 21b67c203e62..4710f7c7495a 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2800,6 +2800,7 @@ struct zap_details {
> struct folio *single_folio; /* Locked folio to be unmapped */
> bool skip_cows; /* Do not zap COWed private pages */
> bool reclaim_pt; /* Need reclaim page tables? */
> + bool reaping; /* Reaping, do not block. */
> zap_flags_t zap_flags; /* Extra flags for zapping */
> };
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 7d7c24c6917c..394b2e931974 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2079,14 +2079,18 @@ static void __zap_vma_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
> unsigned long start, unsigned long end,
> struct zap_details *details)
> {
> + const bool reaping = details && details->reaping;
> +
> VM_WARN_ON_ONCE(start >= end || !range_in_vma(vma, start, end));
>
> - if (vma->vm_file)
> + /* uprobe_munmap() might sleep, so skip it when reaping. */
> + if (vma->vm_file && !reaping)
> uprobe_munmap(vma, start, end);
>
> if (unlikely(is_vm_hugetlb_page(vma))) {
> zap_flags_t zap_flags = details ? details->zap_flags : 0;
>
> + VM_WARN_ON_ONCE(reaping);
> /*
> * vm_file will be NULL when we fail early while instantiating
> * a new mapping. In this case, no pages were mapped yet and
> @@ -2111,11 +2115,12 @@ static void __zap_vma_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
> */
> int zap_vma_for_reaping(struct vm_area_struct *vma)
> {
> + struct zap_details details = {
> + .reaping = true,
> + };
> struct mmu_notifier_range range;
> struct mmu_gather tlb;
>
> - VM_WARN_ON_ONCE(is_vm_hugetlb_page(vma));
> -

I guess because you've moved this safety check into __zap_vma_range()?

> mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
> vma->vm_start, vma->vm_end);
> tlb_gather_mmu(&tlb, vma->vm_mm);
> @@ -2123,7 +2128,7 @@ int zap_vma_for_reaping(struct vm_area_struct *vma)
> tlb_finish_mmu(&tlb);
> return -EBUSY;
> }
> - unmap_page_range(&tlb, vma, range.start, range.end, NULL);
> + __zap_vma_range(&tlb, vma, range.start, range.end, &details);
> mmu_notifier_invalidate_range_end(&range);
> tlb_finish_mmu(&tlb);
> return 0;
> --
> 2.43.0
>