On Fri, 20 Aug 2010 15:41:48 -0700 (PDT)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
> From: Ying Han <yinghan@xxxxxxxxxx>
>
> It's pointless to kill a task if another thread sharing its mm cannot be
> killed to allow future memory freeing. A subsequent patch will prevent
> kills in such cases, but first it's necessary to have a way to flag a
> task that shares memory with an OOM_DISABLE task that doesn't incur an
> additional tasklist scan, which would make select_bad_process() an O(n^2)
> function.
>
> This patch adds an atomic counter to struct mm_struct that follows how
> many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN.
> They cannot be killed by the kernel, so their memory cannot be freed in
> oom conditions.
>
> This only requires task_lock() on the task that we're operating on, it
> does not require mm->mmap_sem since task_lock() pins the mm and the
> operation is atomic.
I don't think lockdep likes us taking task_lock() inside
lock_task_sighand(), in oom_adjust_write():
[ 78.185341]
[ 78.185341] =========================================================
[ 78.185341] [ INFO: possible irq lock inversion dependency detected ]
[ 78.185341] 2.6.36-rc2-mm1 #6
[ 78.185341] ---------------------------------------------------------
[ 78.185341] kworker/0:1/0 just changed the state of lock:
[ 78.185341] (&(&sighand->siglock)->rlock){-.....}, at: [<ffffffff81042d83>] lock_task_sighand+0x9a/0xda
[ 78.185341] but this lock took another, HARDIRQ-unsafe lock in the past:
[ 78.185341] (&(&p->alloc_lock)->rlock){+.+...}
[ 78.185341]
[ 78.185341] and interrupts could create inverse lock ordering between them.
[ 78.185341]
[ 78.185341]
[ 78.185341] other info that might help us debug this:
[ 78.185341] 2 locks held by kworker/0:1/0:
[ 78.185341] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff81044f28>] kill_pid_info+0x0/0x8d
[ 78.185341] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff81042ce9>] lock_task_sighand+0x0/0xda
[ 78.185341]
[ 78.185341] the shortest dependencies between 2nd lock and 1st lock:
[ 78.185341] -> (&(&p->alloc_lock)->rlock){+.+...} ops: 221932 {
[ 78.185341] HARDIRQ-ON-W at:
[ 78.185341] [<ffffffff8105f595>] __lock_acquire+0x67c/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137df6f>] _raw_spin_lock+0x2f/0x62
[ 78.185341] [<ffffffff810c48be>] set_task_comm+0x20/0x61
[ 78.185341] [<ffffffff8104eb0e>] kthreadd+0x21/0xf4
[ 78.185341] [<ffffffff81003814>] kernel_thread_helper+0x4/0x10
[ 78.185341] SOFTIRQ-ON-W at:
[ 78.185341] [<ffffffff8105f5b7>] __lock_acquire+0x69e/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137df6f>] _raw_spin_lock+0x2f/0x62
[ 78.185341] [<ffffffff810c48be>] set_task_comm+0x20/0x61
[ 78.185341] [<ffffffff8104eb0e>] kthreadd+0x21/0xf4
[ 78.185341] [<ffffffff81003814>] kernel_thread_helper+0x4/0x10
[ 78.185341] INITIAL USE at:
[ 78.185341] [<ffffffff8105f602>] __lock_acquire+0x6e9/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137df6f>] _raw_spin_lock+0x2f/0x62
[ 78.185341] [<ffffffff810c48be>] set_task_comm+0x20/0x61
[ 78.185341] [<ffffffff8104eb0e>] kthreadd+0x21/0xf4
[ 78.185341] [<ffffffff81003814>] kernel_thread_helper+0x4/0x10
[ 78.185341] }
[ 78.185341] ... key at: [<ffffffff81b4d568>] __key.46765+0x0/0x8
[ 78.185341] ... acquired at:
[ 78.185341] [<ffffffff8105f701>] __lock_acquire+0x7e8/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137df6f>] _raw_spin_lock+0x2f/0x62
[ 78.185341] [<ffffffff8110b910>] oom_adjust_write+0x144/0x2a9
[ 78.185341] [<ffffffff810c02c4>] vfs_write+0xb1/0x13d
[ 78.185341] [<ffffffff810c0873>] sys_write+0x4a/0x75
[ 78.185341] [<ffffffff810029eb>] system_call_fastpath+0x16/0x1b
[ 78.185341]
[ 78.185341] -> (&(&sighand->siglock)->rlock){-.....} ops: 208770 {
[ 78.185341] IN-HARDIRQ-W at:
[ 78.185341] [<ffffffff8105f51f>] __lock_acquire+0x606/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137e756>] _raw_spin_lock_irqsave+0x3b/0x73
[ 78.185341] [<ffffffff81042d83>] lock_task_sighand+0x9a/0xda
[ 78.185341] [<ffffffff81044bc9>] do_send_sig_info+0x2f/0x72
[ 78.185341] [<ffffffff81044f17>] group_send_sig_info+0x88/0x99
[ 78.185341] [<ffffffff81044f88>] kill_pid_info+0x60/0x8d
[ 78.185341] [<ffffffff8103b79c>] it_real_fn+0x17/0x1b
[ 78.185341] [<ffffffff81051efd>] hrtimer_run_queues+0x167/0x1cb
[ 78.185341] [<ffffffff81041bb3>] run_local_timers+0x9/0x15
[ 78.185341] [<ffffffff81041d7d>] update_process_times+0x2d/0x56
[ 78.185341] [<ffffffff810593ff>] tick_periodic+0x63/0x6f
[ 78.185341] [<ffffffff81059429>] tick_handle_periodic+0x1e/0x6b
[ 78.185341] [<ffffffff81019b2e>] smp_apic_timer_interrupt+0x83/0x96
[ 78.185341] [<ffffffff810033d3>] apic_timer_interrupt+0x13/0x20
[ 78.185341] [<ffffffff810014ca>] cpu_idle+0x48/0x66
[ 78.185341] [<ffffffff813772bd>] start_secondary+0x1b9/0x1bd
[ 78.185341] INITIAL USE at:
[ 78.185341] [<ffffffff8105f602>] __lock_acquire+0x6e9/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137e756>] _raw_spin_lock_irqsave+0x3b/0x73
[ 78.185341] [<ffffffff81043122>] flush_signals+0x1d/0x43
[ 78.185341] [<ffffffff81043172>] ignore_signals+0x2a/0x2c
[ 78.185341] [<ffffffff8104eb16>] kthreadd+0x29/0xf4
[ 78.185341] [<ffffffff81003814>] kernel_thread_helper+0x4/0x10
[ 78.185341] }
[ 78.185341] ... key at: [<ffffffff81b4d538>] __key.47081+0x0/0x8
[ 78.185341] ... acquired at:
[ 78.185341] [<ffffffff8105c566>] check_usage_forwards+0xc0/0xcf
[ 78.185341] [<ffffffff8105ce6f>] mark_lock+0x2f4/0x53f
[ 78.185341] [<ffffffff8105f51f>] __lock_acquire+0x606/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff8137e756>] _raw_spin_lock_irqsave+0x3b/0x73
[ 78.185341] [<ffffffff81042d83>] lock_task_sighand+0x9a/0xda
[ 78.185341] [<ffffffff81044bc9>] do_send_sig_info+0x2f/0x72
[ 78.185341] [<ffffffff81044f17>] group_send_sig_info+0x88/0x99
[ 78.185341] [<ffffffff81044f88>] kill_pid_info+0x60/0x8d
[ 78.185341] [<ffffffff8103b79c>] it_real_fn+0x17/0x1b
[ 78.185341] [<ffffffff81051efd>] hrtimer_run_queues+0x167/0x1cb
[ 78.185341] [<ffffffff81041bb3>] run_local_timers+0x9/0x15
[ 78.185341] [<ffffffff81041d7d>] update_process_times+0x2d/0x56
[ 78.185341] [<ffffffff810593ff>] tick_periodic+0x63/0x6f
[ 78.185341] [<ffffffff81059429>] tick_handle_periodic+0x1e/0x6b
[ 78.185341] [<ffffffff81019b2e>] smp_apic_timer_interrupt+0x83/0x96
[ 78.185341] [<ffffffff810033d3>] apic_timer_interrupt+0x13/0x20
[ 78.185341] [<ffffffff810014ca>] cpu_idle+0x48/0x66
[ 78.185341] [<ffffffff813772bd>] start_secondary+0x1b9/0x1bd
[ 78.185341]
[ 78.185341]
[ 78.185341] stack backtrace:
[ 78.185341] Pid: 0, comm: kworker/0:1 Not tainted 2.6.36-rc2-mm1 #6
[ 78.185341] Call Trace:
[ 78.185341] <IRQ> [<ffffffff8105c497>] print_irq_inversion_bug+0x11e/0x12d
[ 78.185341] [<ffffffff8105c566>] check_usage_forwards+0xc0/0xcf
[ 78.185341] [<ffffffff8105c4a6>] ? check_usage_forwards+0x0/0xcf
[ 78.185341] [<ffffffff8105ce6f>] mark_lock+0x2f4/0x53f
[ 78.185341] [<ffffffff8105f51f>] __lock_acquire+0x606/0x865
[ 78.185341] [<ffffffff8105fbc7>] lock_acquire+0x8b/0xa8
[ 78.185341] [<ffffffff81042d83>] ? lock_task_sighand+0x9a/0xda
[ 78.185341] [<ffffffff8137e756>] _raw_spin_lock_irqsave+0x3b/0x73
[ 78.185341] [<ffffffff81042d83>] ? lock_task_sighand+0x9a/0xda
[ 78.185341] [<ffffffff81042d83>] lock_task_sighand+0x9a/0xda
[ 78.185341] [<ffffffff81042ce9>] ? lock_task_sighand+0x0/0xda
[ 78.185341] [<ffffffff81044bc9>] do_send_sig_info+0x2f/0x72
[ 78.185341] [<ffffffff81044f17>] group_send_sig_info+0x88/0x99
[ 78.185341] [<ffffffff81044e8f>] ? group_send_sig_info+0x0/0x99
[ 78.185341] [<ffffffff8103b785>] ? it_real_fn+0x0/0x1b
[ 78.185341] [<ffffffff81044f88>] kill_pid_info+0x60/0x8d
[ 78.185341] [<ffffffff81044f28>] ? kill_pid_info+0x0/0x8d
[ 78.185341] [<ffffffff8103b785>] ? it_real_fn+0x0/0x1b
[ 78.185341] [<ffffffff8103b79c>] it_real_fn+0x17/0x1b
[ 78.185341] [<ffffffff81051efd>] hrtimer_run_queues+0x167/0x1cb
[ 78.185341] [<ffffffff81041bb3>] run_local_timers+0x9/0x15
[ 78.185341] [<ffffffff81041d7d>] update_process_times+0x2d/0x56
[ 78.185341] [<ffffffff810593ff>] tick_periodic+0x63/0x6f
[ 78.185341] [<ffffffff81059429>] tick_handle_periodic+0x1e/0x6b
[ 78.185341] [<ffffffff81019b2e>] smp_apic_timer_interrupt+0x83/0x96
[ 78.185341] [<ffffffff810033d3>] apic_timer_interrupt+0x13/0x20
[ 78.185341] <EOI> [<ffffffff81381c3a>] ? __atomic_notifier_call_chain+0x0/0x84
[ 78.185341] [<ffffffff81381c3a>] ? __atomic_notifier_call_chain+0x0/0x84
[ 78.185341] [<ffffffff81381c3a>] ? __atomic_notifier_call_chain+0x0/0x84
[ 78.185341] [<ffffffff81009afe>] ? mwait_idle+0x66/0x72
[ 78.185341] [<ffffffff81009af4>] ? mwait_idle+0x5c/0x72
[ 78.185341] [<ffffffff810014ca>] cpu_idle+0x48/0x66
[ 78.185341] [<ffffffff813772bd>] start_secondary+0x1b9/0x1bd
[ 78.185341] [<ffffffff81377104>] ? start_secondary+0x0/0x1bd
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