On Fri, Feb 27, 2026 at 09:08:37PM +0100, David Hildenbrand (Arm) wrote: > Let's factor it out so we can turn unmap_page_range() into a static > function instead, and so oom reaping has a clean interface to call. > > Note that hugetlb is not supported, because it would require a bunch of > hugetlb-specific further actions (see zap_page_range_single_batched()).
Ugh gawd. Hugetlb. > > Signed-off-by: David Hildenbrand (Arm) <[email protected]> Seems reasonable, so: Reviewed-by: Lorenzo Stoakes (Oracle) <[email protected]> > --- > mm/internal.h | 5 +---- > mm/memory.c | 36 ++++++++++++++++++++++++++++++++---- > mm/oom_kill.c | 15 +-------------- > 3 files changed, 34 insertions(+), 22 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 39ab37bb0e1d..df9190f7db0e 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -536,13 +536,10 @@ static inline void sync_with_folio_pmd_zap(struct > mm_struct *mm, pmd_t *pmdp) > } > > struct zap_details; > -void unmap_page_range(struct mmu_gather *tlb, > - struct vm_area_struct *vma, > - unsigned long addr, unsigned long end, > - struct zap_details *details); > void zap_page_range_single_batched(struct mmu_gather *tlb, > struct vm_area_struct *vma, unsigned long addr, > unsigned long size, struct zap_details *details); > +int zap_vma_for_reaping(struct vm_area_struct *vma); > int folio_unmap_invalidate(struct address_space *mapping, struct folio > *folio, > gfp_t gfp); > > diff --git a/mm/memory.c b/mm/memory.c > index e4154f03feac..621f38ae1425 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2054,10 +2054,9 @@ static inline unsigned long zap_p4d_range(struct > mmu_gather *tlb, > return addr; > } > > -void unmap_page_range(struct mmu_gather *tlb, > - struct vm_area_struct *vma, > - unsigned long addr, unsigned long end, > - struct zap_details *details) > +static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct > *vma, > + unsigned long addr, unsigned long end, > + struct zap_details *details) > { > pgd_t *pgd; > unsigned long next; > @@ -2115,6 +2114,35 @@ static void unmap_single_vma(struct mmu_gather *tlb, > } > } > > +/** > + * zap_vma_for_reaping - zap all page table entries in the vma without > blocking > + * @vma: The vma to zap. > + * > + * Zap all page table entries in the vma without blocking for use by the oom > + * killer. Hugetlb vmas are not supported. > + * > + * Returns: 0 on success, -EBUSY if we would have to block. > + */ > +int zap_vma_for_reaping(struct vm_area_struct *vma) > +{ > + struct mmu_notifier_range range; > + struct mmu_gather tlb; > + > + VM_WARN_ON_ONCE(is_vm_hugetlb_page(vma)); > + > + 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); > + if (mmu_notifier_invalidate_range_start_nonblock(&range)) { > + tlb_finish_mmu(&tlb); > + return -EBUSY; > + } > + unmap_page_range(&tlb, vma, range.start, range.end, NULL); > + mmu_notifier_invalidate_range_end(&range); > + tlb_finish_mmu(&tlb); > + return 0; > +} > + > /** > * unmap_vmas - unmap a range of memory covered by a list of vma's > * @tlb: address of the caller's struct mmu_gather > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 0ba56fcd10d5..54b7a8fe5136 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -548,21 +548,8 @@ static bool __oom_reap_task_mm(struct mm_struct *mm) > * count elevated without a good reason. > */ > if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) { > - struct mmu_notifier_range range; > - struct mmu_gather tlb; > - > - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, > - mm, vma->vm_start, > - vma->vm_end); > - tlb_gather_mmu(&tlb, mm); > - if > (mmu_notifier_invalidate_range_start_nonblock(&range)) { > - tlb_finish_mmu(&tlb); > + if (zap_vma_for_reaping(vma)) > ret = false; > - continue; > - } > - unmap_page_range(&tlb, vma, range.start, range.end, > NULL); > - mmu_notifier_invalidate_range_end(&range); > - tlb_finish_mmu(&tlb); > } > } > > -- > 2.43.0 >
