Re: [PATCH v2] fs/hugetlbfs/inode.c: Ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr

[Oscar Salvador]

On Tue, Jul 09, 2024 at 04:21:22AM -0500, Donet Tom wrote:
> generic_hugetlb_get_unmapped_area() was returning an address less
> than mmap_min_addr if the mmap argument addr, after alignment, was
> less than mmap_min_addr, causing mmap to fail.
> 
> This is because current generic_hugetlb_get_unmapped_area() code does
> not take into account mmap_min_addr.
> 
> This patch ensures that generic_hugetlb_get_unmapped_area() always returns
> an address that is greater than mmap_min_addr. Additionally, similar to
> generic_get_unmapped_area(), vm_end_gap() checks are included to ensure
> that the address is within the limit.

Hi Donet,

jfyi: I am already working on other parts of the kernel to avoid hugetlb code
duplication vs mm core.
I am also working on getting rid of hugetlb-unmapped_area specific code
[1].
I still need to perform some more tests but looks promising
code-deletion-wise:

  arch/parisc/mm/hugetlbpage.c     |  23 -------
  arch/powerpc/mm/book3s64/slice.c |  49 ++++++++------
  arch/s390/mm/hugetlbpage.c       |  84 ------------------------
  arch/s390/mm/mmap.c              |  14 +++-
  arch/sparc/kernel/sys_sparc_32.c |  16 +++--
  arch/sparc/kernel/sys_sparc_64.c |  36 ++++++++---
  arch/sparc/mm/hugetlbpage.c      | 108 -------------------------------
  arch/x86/kernel/sys_x86_64.c     |  27 +++++---
  arch/x86/mm/hugetlbpage.c        | 100 ----------------------------
  fs/hugetlbfs/inode.c             |  97 ++-------------------------
  include/linux/hugetlb.h          |  10 +++
  mm/mmap.c                        |  25 ++++++-
  12 files changed, 139 insertions(+), 450 deletions(-)

I plan to post it in a day or two.

[1] https://github.com/leberus/linux/tree/hugetlb-unmapped-area


-- 
Oscar Salvador
SUSE Labs