[v3,0/5] Use nth_page() in place of direct struct page manipulation

Message

Zi Yan Sept. 13, 2023, 8:12 p.m. UTC

From: Zi Yan <[e-mail]>

On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be
contiguous, since each memory section's memmap might be allocated
independently. hugetlb pages can go beyond a memory section size, thus
direct struct page manipulation on hugetlb pages/subpages might give
wrong struct page. Kernel provides nth_page() to do the manipulation
properly. Use that whenever code can see hugetlb pages.

The patches are on top of next-20230913

Changes:

From v2:
1. Fixed the subject and the commit log of Patch 3 (David Hildenbrand)

From v1:
1. Separated first patch into three and add Fixes for better backport.

Zi Yan (5):
  mm/cma: use nth_page() in place of direct struct page manipulation.
  mm/hugetlb: use nth_page() in place of direct struct page
    manipulation.
  mm/memory_hotplug: use pfn math in place of direct struct page
    manipulation.
  fs: use nth_page() in place of direct struct page manipulation.
  mips: use nth_page() in place of direct struct page manipulation.

 arch/mips/mm/cache.c | 2 +-
 fs/hugetlbfs/inode.c | 4 ++--
 mm/cma.c             | 2 +-
 mm/hugetlb.c         | 2 +-
 mm/memory_hotplug.c  | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

Comments

Andrew Morton Sept. 13, 2023, 9:12 p.m. UTC | #1

On Wed, 13 Sep 2023 16:12:43 -0400 Zi Yan <[e-mail]> wrote:

> On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be
> contiguous, since each memory section's memmap might be allocated
> independently. hugetlb pages can go beyond a memory section size, thus
> direct struct page manipulation on hugetlb pages/subpages might give
> wrong struct page. Kernel provides nth_page() to do the manipulation
> properly. Use that whenever code can see hugetlb pages.

for (each patch) {

	Can we please explain why -stable backporting is recommended?

	Such an explanation will, as always, include a description of the
	user-visible effects of the bug.

	Some of the Fixes: targets are very old: 5 years.  Has something
	changed to bring these flaws to light?  Or is it from code inspection?
}

Thanks.