Re: [PATCH] powerpc/code-patching: Fix oops with DEBUG_VM enabled

On Fri, 16 Dec 2022 23:59:13 +1100, Michael Ellerman wrote:

Nathan reported that the new per-cpu mm patching oopses if DEBUG_VM is
enabled:

  ------------[ cut here ]------------
  kernel BUG at arch/powerpc/mm/pgtable.c:333!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc2+ #1
  Hardware name: IBM PowerNV (emulated by qemu) POWER9 0x4e1200 opal:v7.0 PowerNV
  ...
  NIP assert_pte_locked+0x180/0x1a0
  LR  assert_pte_locked+0x170/0x1a0
  Call Trace:
    0x60000000 (unreliable)
    patch_instruction+0x618/0x6d0
    arch_prepare_kprobe+0xfc/0x2d0
    register_kprobe+0x520/0x7c0
    arch_init_kprobes+0x28/0x3c
    init_kprobes+0x108/0x184
    do_one_initcall+0x60/0x2e0
    kernel_init_freeable+0x1f0/0x3e0
    kernel_init+0x34/0x1d0
    ret_from_kernel_thread+0x5c/0x64

[...]

Applied to powerpc/next.

[1/1] powerpc/code-patching: Fix oops with DEBUG_VM enabled
      https://git.kernel.org/powerpc/c/980411a4d1bb925d28cd9e8d8301dc982ece788d

cheers