Dave Jiang <dave.jiang@xxxxxxxxx> writes:
> It looks like I missed the PUD path when doing VM_MIXEDMAP removal.
> This can be triggered by:
> 1. Boot with memmap=4G!8G
> 2. build ndctl with destructive flag on
> 3. make TESTS=device-dax check
>
> [ +0.000675] kernel BUG at mm/huge_memory.c:824!
>
> Applying the same change that was applied to vmf_insert_pfn_pmd() in the
> original patch.
>
> Fixes: e1fb4a08649 ("dax: remove VM_MIXEDMAP for fsdax and device dax")
>
> Reported-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Acked-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c3bc7e9c9a2a..533f9b00147d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -821,11 +821,11 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
> * but we need to be consistent with PTEs and architectures that
> * can't support a 'special' bit.
> */
> - BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
> + BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
> + !pfn_t_devmap(pfn));
> BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
> (VM_PFNMAP|VM_MIXEDMAP));
> BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
> - BUG_ON(!pfn_t_devmap(pfn));
>
> if (addr < vma->vm_start || addr >= vma->vm_end)
> return VM_FAULT_SIGBUS;
>
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