Eric Lee / smarc-ti-linux-kernel

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Commit e9dd685ce81815811fb4da72e6ab10a694ac8468

Authored by Steven Rostedt
Committed by Ingo Molnar
1 parent 6acbfb9697
Exists in ti-lsk-linux-4.1.y and in 12 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.15.y

sched/numa: Fix use of spin_{un}lock_irq() when interrupts are disabled 

As Peter Zijlstra told me, we have the following path:

do_exit()
  exit_itimers()
    itimer_delete()
      spin_lock_irqsave(&timer->it_lock, &flags);
      timer_delete_hook(timer);
        kc->timer_del(timer) := posix_cpu_timer_del()
          put_task_struct()
            __put_task_struct()
              task_numa_free()
                spin_lock(&grp->lock);

Which means that task_numa_free() can be called with interrupts
disabled, which means that we should not be using spin_lock_irq() but
spin_lock_irqsave() instead. Otherwise we are enabling interrupts while
holding an interrupt unsafe lock!

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner<tglx@linutronix.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140527182541.GH11096@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Showing 1 changed file with 4 additions and 3 deletions Side-by-side Diff

... ... @@ -1707,18 +1707,19 @@
1707 1707 void task_numa_free(struct task_struct *p)
1708 1708 {
1709 1709 struct numa_group *grp = p->numa_group;
1710   - int i;
1711 1710 void *numa_faults = p->numa_faults_memory;
  1711 + unsigned long flags;
  1712 + int i;
1712 1713  
1713 1714 if (grp) {
1714   - spin_lock_irq(&grp->lock);
  1715 + spin_lock_irqsave(&grp->lock, flags);
1715 1716 for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
1716 1717 grp->faults[i] -= p->numa_faults_memory[i];
1717 1718 grp->total_faults -= p->total_numa_faults;
1718 1719  
1719 1720 list_del(&p->numa_entry);
1720 1721 grp->nr_tasks--;
1721   - spin_unlock_irq(&grp->lock);
  1722 + spin_unlock_irqrestore(&grp->lock, flags);
1722 1723 rcu_assign_pointer(p->numa_group, NULL);
1723 1724 put_numa_group(grp);
1724 1725 }