[PATCH v1 01/16] mm/madvise: drop range checks in madvise_free_single_vma()
From: "David Hildenbrand (Arm)" <david@kernel.org>
Date: 2026-02-27 20:09:24
Also in:
bpf, dri-devel, intel-gfx, kvm, linux-fsdevel, linux-mm, linux-perf-users, linux-rdma, linux-s390, linuxppc-dev, lkml, rust-for-linux
Subsystem:
memory management, memory mapping - madvise (memory advice), the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, David Hildenbrand, Linus Torvalds
madvise_vma_behavior()-> madvise_dontneed_free()->madvise_free_single_vma()
is only called from madvise_walk_vmas()
(a) After try_vma_read_lock() confirmed that the whole range falls into
a single VMA (see is_vma_lock_sufficient()).
(b) After adjusting the range to the VMA in the loop afterwards.
madvise_dontneed_free() might drop the MM lock when handling
userfaultfd, but it properly looks up the VMA again to adjust the range.
So in madvise_free_single_vma(), the given range should always fall into
a single VMA and should also span at least one page.
Let's drop the error checks.
The code now matches what we do in madvise_dontneed_single_vma(), where
we call zap_vma_range_batched() that documents: "The range must fit into
one VMA.". Although that function still adjusts that range, we'll change
that soon.
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
mm/madvise.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index c0370d9b4e23..efc04334a000 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c@@ -799,9 +799,10 @@ static int madvise_free_single_vma(struct madvise_behavior *madv_behavior) { struct mm_struct *mm = madv_behavior->mm; struct vm_area_struct *vma = madv_behavior->vma; - unsigned long start_addr = madv_behavior->range.start; - unsigned long end_addr = madv_behavior->range.end; - struct mmu_notifier_range range; + struct mmu_notifier_range range = { + .start = madv_behavior->range.start, + .end = madv_behavior->range.end, + }; struct mmu_gather *tlb = madv_behavior->tlb; struct mm_walk_ops walk_ops = { .pmd_entry = madvise_free_pte_range,
@@ -811,12 +812,6 @@ static int madvise_free_single_vma(struct madvise_behavior *madv_behavior) if (!vma_is_anonymous(vma)) return -EINVAL; - range.start = max(vma->vm_start, start_addr); - if (range.start >= vma->vm_end) - return -EINVAL; - range.end = min(vma->vm_end, end_addr); - if (range.end <= vma->vm_start) - return -EINVAL; mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, range.start, range.end);
--
2.43.0