From: Dave Jiang <dave.jiang@xxxxxxxxx> Subject: mm: fix BUG_ON() in vmf_insert_pfn_pud() from VM_MIXEDMAP removal 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. Link: http://lkml.kernel.org/r/153565957352.35524.1005746906902065126.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxx Fixes: e1fb4a08649 ("dax: remove VM_MIXEDMAP for fsdax and device dax") Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> Reported-by: Vishal Verma <vishal.l.verma@xxxxxxxxx> Tested-by: Vishal Verma <vishal.l.verma@xxxxxxxxx> Acked-by: Jeff Moyer <jmoyer@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/huge_memory.c~mm-fix-bug_on-in-vmf_insert_pfn_pud-from-vm_mixedmap-removal +++ a/mm/huge_memory.c @@ -821,11 +821,11 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_ * 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; _
