• Kajol Jain's avatar
    powerpc/imc-pmu: Fix use of mutex in IRQs disabled section · 76d588dd
    Kajol Jain authored
    Current imc-pmu code triggers a WARNING with CONFIG_DEBUG_ATOMIC_SLEEP
    and CONFIG_PROVE_LOCKING enabled, while running a thread_imc event.
    
    Command to trigger the warning:
      # perf stat -e thread_imc/CPM_CS_FROM_L4_MEM_X_DPTEG/ sleep 5
    
       Performance counter stats for 'sleep 5':
    
                       0      thread_imc/CPM_CS_FROM_L4_MEM_X_DPTEG/
    
             5.002117947 seconds time elapsed
    
             0.000131000 seconds user
             0.001063000 seconds sys
    
    Below is snippet of the warning in dmesg:
    
      BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
      in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2869, name: perf-exec
      preempt_count: 2, expected: 0
      4 locks held by perf-exec/2869:
       #0: c00000004325c540 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: bprm_execve+0x64/0xa90
       #1: c00000004325c5d8 (&sig->exec_update_lock){++++}-{3:3}, at: begin_new_exec+0x460/0xef0
       #2: c0000003fa99d4e0 (&cpuctx_lock){-...}-{2:2}, at: perf_event_exec+0x290/0x510
       #3: c000000017ab8418 (&ctx->lock){....}-{2:2}, at: perf_event_exec+0x29c/0x510
      irq event stamp: 4806
      hardirqs last  enabled at (4805): [<c000000000f65b94>] _raw_spin_unlock_irqrestore+0x94/0xd0
      hardirqs last disabled at (4806): [<c0000000003fae44>] perf_event_exec+0x394/0x510
      softirqs last  enabled at (0): [<c00000000013c404>] copy_process+0xc34/0x1ff0
      softirqs last disabled at (0): [<0000000000000000>] 0x0
      CPU: 36 PID: 2869 Comm: perf-exec Not tainted 6.2.0-rc2-00011-g1247637727f2 #61
      Hardware name: 8375-42A POWER9 0x4e1202 opal:v7.0-16-g9b85f7d961 PowerNV
      Call Trace:
        dump_stack_lvl+0x98/0xe0 (unreliable)
        __might_resched+0x2f8/0x310
        __mutex_lock+0x6c/0x13f0
        thread_imc_event_add+0xf4/0x1b0
        event_sched_in+0xe0/0x210
        merge_sched_in+0x1f0/0x600
        visit_groups_merge.isra.92.constprop.166+0x2bc/0x6c0
        ctx_flexible_sched_in+0xcc/0x140
        ctx_sched_in+0x20c/0x2a0
        ctx_resched+0x104/0x1c0
        perf_event_exec+0x340/0x510
        begin_new_exec+0x730/0xef0
        load_elf_binary+0x3f8/0x1e10
      ...
      do not call blocking ops when !TASK_RUNNING; state=2001 set at [<00000000fd63e7cf>] do_nanosleep+0x60/0x1a0
      WARNING: CPU: 36 PID: 2869 at kernel/sched/core.c:9912 __might_sleep+0x9c/0xb0
      CPU: 36 PID: 2869 Comm: sleep Tainted: G        W          6.2.0-rc2-00011-g1247637727f2 #61
      Hardware name: 8375-42A POWER9 0x4e1202 opal:v7.0-16-g9b85f7d961 PowerNV
      NIP:  c000000000194a1c LR: c000000000194a18 CTR: c000000000a78670
      REGS: c00000004d2134e0 TRAP: 0700   Tainted: G        W           (6.2.0-rc2-00011-g1247637727f2)
      MSR:  9000000000021033 <SF,HV,ME,IR,DR,RI,LE>  CR: 48002824  XER: 00000000
      CFAR: c00000000013fb64 IRQMASK: 1
    
    The above warning triggered because the current imc-pmu code uses mutex
    lock in interrupt disabled sections. The function mutex_lock()
    internally calls __might_resched(), which will check if IRQs are
    disabled and in case IRQs are disabled, it will trigger the warning.
    
    Fix the issue by changing the mutex lock to spinlock.
    
    Fixes: 8f95faaa ("powerpc/powernv: Detect and create IMC device")
    Reported-by: default avatarMichael Petlan <mpetlan@redhat.com>
    Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Signed-off-by: default avatarKajol Jain <kjain@linux.ibm.com>
    [mpe: Fix comments, trim oops in change log, add reported-by tags]
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20230106065157.182648-1-kjain@linux.ibm.com
    76d588dd
imc-pmu.c 46.5 KB