• Tetsuo Handa's avatar
    sched/fair: Fix RCU stall upon -ENOMEM in sched_create_group() · 7f1a169b
    Tetsuo Handa authored
    When alloc_fair_sched_group() in sched_create_group() fails,
    free_sched_group() is called, and free_fair_sched_group() is called by
    free_sched_group(). Since destroy_cfs_bandwidth() is called by
    free_fair_sched_group() without calling init_cfs_bandwidth(),
    RCU stall occurs at hrtimer_cancel():
    
      INFO: rcu_sched self-detected stall on CPU { 1}  (t=60000 jiffies g=13074 c=13073 q=0)
      Task dump for CPU 1:
      (fprintd)       R  running task        0  6249      1 0x00000088
      ...
      Call Trace:
       <IRQ>  [<ffffffff81094988>] sched_show_task+0xa8/0x110
       [<ffffffff81097acd>] dump_cpu_task+0x3d/0x50
       [<ffffffff810c3a80>] rcu_dump_cpu_stacks+0x90/0xd0
       [<ffffffff810c7751>] rcu_check_callbacks+0x491/0x700
       [<ffffffff810cbf2b>] update_process_times+0x4b/0x80
       [<ffffffff810db046>] tick_sched_handle.isra.20+0x36/0x50
       [<ffffffff810db0a2>] tick_sched_timer+0x42/0x70
       [<ffffffff810ccb19>] __run_hrtimer+0x69/0x1a0
       [<ffffffff810db060>] ? tick_sched_handle.isra.20+0x50/0x50
       [<ffffffff810ccedf>] hrtimer_interrupt+0xef/0x230
       [<ffffffff810452cb>] local_apic_timer_interrupt+0x3b/0x70
       [<ffffffff8164a465>] smp_apic_timer_interrupt+0x45/0x60
       [<ffffffff816485bd>] apic_timer_interrupt+0x6d/0x80
       <EOI>  [<ffffffff810cc588>] ? lock_hrtimer_base.isra.23+0x18/0x50
       [<ffffffff81193cf1>] ? __kmalloc+0x211/0x230
       [<ffffffff810cc9d2>] hrtimer_try_to_cancel+0x22/0xd0
       [<ffffffff81193cf1>] ? __kmalloc+0x211/0x230
       [<ffffffff810ccaa2>] hrtimer_cancel+0x22/0x30
       [<ffffffff810a3cb5>] free_fair_sched_group+0x25/0xd0
       [<ffffffff8108df46>] free_sched_group+0x16/0x40
       [<ffffffff810971bb>] sched_create_group+0x4b/0x80
       [<ffffffff810aa383>] sched_autogroup_create_attach+0x43/0x1c0
       [<ffffffff8107dc9c>] sys_setsid+0x7c/0x110
       [<ffffffff81647729>] system_call_fastpath+0x12/0x17
    
    Check whether init_cfs_bandwidth() was called before calling
    destroy_cfs_bandwidth().
    Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    [ Move the check into destroy_cfs_bandwidth() to aid compilability. ]
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Paul Turner <pjt@google.com>
    Cc: Ben Segall <bsegall@google.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Link: http://lkml.kernel.org/r/201412252210.GCC30204.SOMVFFOtQJFLOH@I-love.SAKURA.ne.jpSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    7f1a169b
fair.c 212 KB