Re: [PATCH v2] arm64: io: Reject non-user protection in ioremap_prot()

On Fri, 11 Sep 2026 09:58:59 +0800, Zeng Heng wrote:

Mapping a stack-top page via /dev/mem with PROT_NONE and then
reading that process's /proc/<pid>/cmdline triggers a spurious WARN
in ioremap_prot() through generic_access_phys():

  WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys
  Call trace:
    generic_access_phys+0x1c8/0x228 (P)
    __access_remote_vm+0x2b4/0x398
    access_remote_vm+0x14/0x30
    get_mm_cmdline+0xf8/0x2a0
    proc_pid_cmdline_read+0x68/0x120

[...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64: io: Reject non-user protection in ioremap_prot()
      https://git.kernel.org/arm64/c/bb756b11ad63

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev