[PATCH v4 28/38] mm: drop some redundant checks around hugetlb VMAs
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From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Date: 2026-10-03 16:43:02
Also in:
bpf, fuse-devel, kvm, kvm-riscv, kvmarm, linux-arch, linux-doc, linux-fbdev, linux-fsdevel, linux-mm, linux-perf-users, linux-rdma, linux-riscv, linux-s390, linux-scsi, linux-sound, linux-usb, linuxppc-dev, lkml, selinux, sparclinux
Subsystem:
arm64 port (aarch64 architecture), drm drivers, drm drivers and misc gpu patches, kernel virtual machine for arm64 (kvm/arm64), memory management, memory management - migration, the rest · Maintainers:
Catalin Marinas, Will Deacon, David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Marc Zyngier, Oliver Upton, Andrew Morton, David Hildenbrand, Linus Torvalds
3 review trailers (3 from subsystem maintainers); queued in linux-next as f7aca85ac897 on 2026-10-09.
Adjust code which inadvertently perform redundant checks on hugetlb VMAs and clean them up: * hugetlb VMAs have VMA_DONTEXPAND_BIT set so a VMA_SPECIAL_FLAGS check suffices. (migrate_vma_setup() regains an explicit hugetlb test later in the series, once VMA_SPECIAL_FLAGS is removed.) * hugetlb VMAs unconditionally set vma->vm_ops, so they are never anonymous. * hugetlb VMAs do not set VMA_PFNMAP_BIT so checking for this is redundant. While we're here also drop a VM_BUG_ON() which the simplified check above makes unreachable, and use the new VMA flag API. No functional change intended. Acked-by: Marc Zyngier <maz@kernel.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: David Hildenbrand (Arm) <david@kernel.org> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> --- arch/arm64/kvm/mmu.c | 4 +--- drivers/gpu/drm/drm_gpusvm.c | 3 +-- mm/migrate_device.c | 4 ++-- 3 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index a7968f8d24bf..3c1240ffc38d 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c@@ -1463,14 +1463,12 @@ static int get_vma_page_shift(struct vm_area_struct *vma, unsigned long hva) { unsigned long pa; - if (vma_is_hugetlb(vma) && !(vma->vm_flags & VM_PFNMAP)) + if (vma_is_hugetlb(vma)) return huge_page_shift(hstate_vma(vma)); if (!(vma->vm_flags & VM_PFNMAP)) return PAGE_SHIFT; - VM_BUG_ON(vma_is_hugetlb(vma)); - pa = (vma->vm_pgoff << PAGE_SHIFT) + (hva - vma->vm_start); #ifndef __PAGETABLE_PMD_FOLDED
diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index a1d4989b0b61..fab34fea99c2 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c@@ -1141,8 +1141,7 @@ drm_gpusvm_range_find_or_insert(struct drm_gpusvm *gpusvm, * limitations. If/when migrate_vma_* add more support, this logic will * have to change. */ - migrate_devmem = ctx->devmem_possible && - vma_is_anonymous(vas) && !vma_is_hugetlb(vas); + migrate_devmem = ctx->devmem_possible && vma_is_anonymous(vas); chunk_size = drm_gpusvm_range_chunk_size(gpusvm, notifier, vas, fault_addr, gpuva_start,
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index c38cbaaef5a4..b9c453c28795 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c@@ -743,8 +743,8 @@ int migrate_vma_setup(struct migrate_vma *args) args->start &= PAGE_MASK; args->end &= PAGE_MASK; - if (!args->vma || vma_is_hugetlb(args->vma) || - (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma)) + if (!args->vma || vma_test_any_mask(args->vma, VMA_SPECIAL_FLAGS) || + vma_is_dax(args->vma)) return -EINVAL; if (nr_pages <= 0) return -EINVAL;
--
2.55.0