On Fri, Jun 13, 2025 at 10:44:42AM -0700, Alex Mastro wrote:
> Thank you Peter!
>
> I packported this series to our 6.13.2 tree and validated that it does indeed
> provide equivalent, optimal faulting to our manual alignment approach when we
> mmap with !MAP_FIXED. This addresses the issue we discovered in [1].
>
> The test case is performing mmap with offset=0x40006000000, size=0xdf9e00000,
> and we see that the head and tail (975) are faulted at 2M, and middle (54) at
> 1G. The vma returned by mmap looks nice: 0x7f8646000000.
>
> $ sudo bpftrace -q -e 'fexit:vfio_pci_mmap_huge_fault { printf("order=%d, ret=0x%x\n", args.order, retval); }' 2>&1 > ~/dump
> $ cat ~/dump | sort | uniq -c | sort -nr
> 975 order=9, ret=0x100
> 54 order=18, ret=0x100
> 2 order=18, ret=0x800
>
> [1] https://lore.kernel.org/linux-pci/20250529214414.1508155-1-amastro@xxxxxx/
>
> Tested-by: Alex Mastro <amastro@xxxxxx>
Great to know it works as expected, thanks for the quick feedback!
--
Peter Xu
