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| author | Ingo Molnar <mingo@elte.hu> | 2009-11-26 08:29:10 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-26 08:29:10 +0100 |
| commit | 67f2de0bf9141dd9fe9189d0caaa28d7ad21a523 (patch) | |
| tree | 6e1693295e6a38efa0a269429d74418f16a76027 | |
| parent | b803090615ccec669681ff85ce28671e7bfefa3d (diff) | |
| download | blackbird-op-linux-67f2de0bf9141dd9fe9189d0caaa28d7ad21a523.tar.gz blackbird-op-linux-67f2de0bf9141dd9fe9189d0caaa28d7ad21a523.zip | |
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks
This warning:
[ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000
[ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517
[ 847.207360] caller is show_stack_log_lvl+0x2e/0x241
[ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761
[ 847.213395] Call Trace:
[ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a
[ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241
[ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e
[ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9
[ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199
[ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f
[ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50
[ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50
[ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f
[ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20
[ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30
[ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10
[ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f
[ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20
Happens because on preempt-RCU, khungd calls show_stack() with
preemption enabled.
Make sure we are not preemptible while walking the IRQ and exception
stacks on 64-bit. (32-bit stack dumping is preemption safe.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/dumpstack_64.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index cfec478a4e42..8e740934bd1f 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -206,19 +206,22 @@ void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *sp, unsigned long bp, char *log_lvl) { + unsigned long *irq_stack_end; + unsigned long *irq_stack; unsigned long *stack; + int cpu; int i; - const int cpu = smp_processor_id(); - unsigned long *irq_stack_end = - (unsigned long *)(per_cpu(irq_stack_ptr, cpu)); - unsigned long *irq_stack = - (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE); + + preempt_disable(); + cpu = smp_processor_id(); + + irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu)); + irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE); /* - * debugging aid: "show_stack(NULL, NULL);" prints the - * back trace for this cpu. + * Debugging aid: "show_stack(NULL, NULL);" prints the + * back trace for this cpu: */ - if (sp == NULL) { if (task) sp = (unsigned long *)task->thread.sp; @@ -242,6 +245,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, printk(" %016lx", *stack++); touch_nmi_watchdog(); } + preempt_enable(); + printk("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); } |
