The patch titled
Subject: mm: add vma_lookup(), update find_vma_intersection() comments
has been added to the -mm tree. Its filename is
mm-add-vma_lookup-update-find_vma_intersection-comments.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-add-vma_lookup-update-find_vma_intersection-comments.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-add-vma_lookup-update-find_vma_intersection-comments.patch
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From: Liam Howlett <liam.howlett@xxxxxxxxxx>
Subject: mm: add vma_lookup(), update find_vma_intersection() comments
Patch series "mm: Add vma_lookup()", v2.
Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.
Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.
The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma. This results in a bug that is often overlooked for a long time.
Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().
This patch (of 22):
Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.
Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.
The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma. This results in a bug that is often overlooked for a long time.
Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().
Also change find_vma_intersection() comments and declaration to be of the
correct length and add kernel documentation style comment.
Link: https://lkml.kernel.org/r/20210521174745.2219620-1-Liam.Howlett@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210521174745.2219620-2-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reviewed-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 36 ++++++++++++++++++++++++++++++++----
1 file changed, 32 insertions(+), 4 deletions(-)
--- a/include/linux/mm.h~mm-add-vma_lookup-update-find_vma_intersection-comments
+++ a/include/linux/mm.h
@@ -2678,17 +2678,45 @@ extern struct vm_area_struct * find_vma(
extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
struct vm_area_struct **pprev);
-/* Look up the first VMA which intersects the interval start_addr..end_addr-1,
- NULL if none. Assume start_addr < end_addr. */
-static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
+/**
+ * find_vma_intersection() - Look up the first VMA which intersects the interval
+ * @mm: The process address space.
+ * @start_addr: The inclusive start user address.
+ * @end_addr: The exclusive end user address.
+ *
+ * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
+ * start_addr < end_addr.
+ */
+static inline
+struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
+ unsigned long start_addr,
+ unsigned long end_addr)
{
- struct vm_area_struct * vma = find_vma(mm,start_addr);
+ struct vm_area_struct *vma = find_vma(mm, start_addr);
if (vma && end_addr <= vma->vm_start)
vma = NULL;
return vma;
}
+/**
+ * vma_lookup() - Find a VMA at a specific address
+ * @mm: The process address space.
+ * @addr: The user address.
+ *
+ * Return: The vm_area_struct at the given address, %NULL otherwise.
+ */
+static inline
+struct vm_area_struct *vma_lookup(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma = find_vma(mm, addr);
+
+ if (vma && addr < vma->vm_start)
+ vma = NULL;
+
+ return vma;
+}
+
static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
{
unsigned long vm_start = vma->vm_start;
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
mm-mmap-introduce-unlock_range-for-code-cleanup.patch
mm-mmap-use-find_vma_intersection-in-do_mmap-for-overlap.patch
mm-add-vma_lookup-update-find_vma_intersection-comments.patch
drm-i915-selftests-use-vma_lookup-in-__igt_mmap.patch
arch-arc-kernel-troubleshoot-use-vma_lookup-instead-of-find_vma.patch
arch-arm64-kvm-use-vma_lookup-instead-of-find_vma_intersection.patch
arch-powerpc-kvm-book3s_hv_uvmem-use-vma_lookup-instead-of-find_vma_intersection.patch
arch-powerpc-kvm-book3s-use-vma_lookup-in-kvmppc_hv_setup_htab_rma.patch
arch-mips-kernel-traps-use-vma_lookup-instead-of-find_vma.patch
arch-m68k-kernel-sys_m68k-use-vma_lookup-in-sys_cacheflush.patch
x86-sgx-use-vma_lookup-in-sgx_encl_find.patch
virt-kvm-use-vma_lookup-instead-of-find_vma_intersection.patch
vfio-use-vma_lookup-instead-of-find_vma_intersection.patch
net-ipv5-tcp-use-vma_lookup-in-tcp_zerocopy_receive.patch
drm-amdgpu-use-vma_lookup-in-amdgpu_ttm_tt_get_user_pages.patch
media-videobuf2-use-vma_lookup-in-get_vaddr_frames.patch
misc-sgi-gru-grufault-use-vma_lookup-in-gru_find_vma.patch
kernel-events-uprobes-use-vma_lookup-in-find_active_uprobe.patch
lib-test_hmm-use-vma_lookup-in-dmirror_migrate.patch
mm-ksm-use-vma_lookup-in-find_mergeable_vma.patch
mm-migrate-use-vma_lookup-in-do_pages_stat_array.patch
mm-mremap-use-vma_lookup-in-vma_to_resize.patch
mm-memoryc-use-vma_lookup-in-__access_remote_vm.patch
mm-mempolicy-use-vma_lookup-in-__access_remote_vm.patch
