[arm-platforms:kvm-arm64/mmu/guest-MMIO-guard 18/18] mm/ioremap.c:31:13: warning: no previous prototype for 'ioremap_page_range_hook'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/mmu/guest-MMIO-guard
head:   63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
commit: 63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd [18/18] guest hacks
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?id=63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
        git remote add arm-platforms https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
        git fetch --no-tags arm-platforms kvm-arm64/mmu/guest-MMIO-guard
        git checkout 63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
        # save the attached .config to linux build tree
        make W=1 ARCH=um SUBARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

quoted

mm/ioremap.c:31:13: warning: no previous prototype for 'ioremap_page_range_hook' [-Wmissing-prototypes]

      31 | void __weak ioremap_page_range_hook(unsigned long addr, unsigned long end,
         |             ^~~~~~~~~~~~~~~~~~~~~~~


vim +/ioremap_page_range_hook +31 mm/ioremap.c

    30	
  > 31	void __weak ioremap_page_range_hook(unsigned long addr, unsigned long end,
    32					    phys_addr_t phys_addr, pgprot_t prot)
    33	{
    34	}
    35	

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