Re: [PATCH] powerpc/64s: Fix native_hpte_remove() to be irq-safe

On Wed, 17 May 2023 22:30:33 +1000, Michael Ellerman wrote:

Lockdep warns that the use of the hpte_lock in native_hpte_remove() is
not safe against an IRQ coming in:

  ================================
  WARNING: inconsistent lock state
  6.4.0-rc2-g0c54f4d30ecc #1 Not tainted
  --------------------------------
  inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
  qemu-system-ppc/93865 [HC0[0]:SC0[0]:HE1:SE1] takes:
  c0000000021f5180 (hpte_lock){+.?.}-{0:0}, at: native_lock_hpte+0x8/0xd0
  {IN-SOFTIRQ-W} state was registered at:
    lock_acquire+0x134/0x3f0
    native_lock_hpte+0x44/0xd0
    native_hpte_insert+0xd4/0x2a0
    __hash_page_64K+0x218/0x4f0
    hash_page_mm+0x464/0x840
    do_hash_fault+0x11c/0x260
    data_access_common_virt+0x210/0x220
    __ip_select_ident+0x140/0x150
    ...
    net_rx_action+0x3bc/0x440
    __do_softirq+0x180/0x534
    ...
    sys_sendmmsg+0x34/0x50
    system_call_exception+0x128/0x320
    system_call_common+0x160/0x2e4
  ...
   Possible unsafe locking scenario:

[...]

Applied to powerpc/fixes.

[1/1] powerpc/64s: Fix native_hpte_remove() to be irq-safe
      https://git.kernel.org/powerpc/c/8bbe9fee5848371d4af101be445303cac8d880c5

cheers