(Appears to have been present in -rc2-mmotm1117 as well, and maybe earlier. I
suspect mcelog wasn't getting run at boot due to my fighting with systemd, so I
didn't see it).
[ 146.195836] ===================================================
[ 146.195839] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 146.195841] ---------------------------------------------------
[ 146.195844] arch/x86/kernel/cpu/mcheck/mce.c:1628 invoked rcu_dereference_check() without protection!
[ 146.195847]
[ 146.195847] other info that might help us debug this:
[ 146.195848]
[ 146.195850]
[ 146.195850] rcu_scheduler_active = 1, debug_locks = 1
[ 146.195853] no locks held by mcelog/3806.
[ 146.195855]
[ 146.195855] stack backtrace:
[ 146.195858] Pid: 3806, comm: mcelog Tainted: G W 2.6.37-rc3-mmotm1123 #4
[ 146.195860] Call Trace:
[ 146.195869] [<ffffffff81069538>] lockdep_rcu_dereference+0x9d/0xa5
[ 146.195875] [<ffffffff810139ea>] mce_poll+0x66/0x74
[ 146.195880] [<ffffffff8110a62e>] do_sys_poll+0x23b/0x3a5
[ 146.195885] [<ffffffff811095ad>] ? __pollwait+0x0/0xc7
[ 146.195889] [<ffffffff81109674>] ? pollwake+0x0/0x4f
[ 146.195893] [<ffffffff81109674>] ? pollwake+0x0/0x4f
[ 146.195898] [<ffffffff81094c0e>] ? __rcu_read_unlock+0x28f/0x2ab
[ 146.195903] [<ffffffff810d565f>] ? __do_fault+0x256/0x3e5
[ 146.195908] [<ffffffff81068775>] ? look_up_lock_class+0x5f/0xc4
[ 146.195912] [<ffffffff810d565f>] ? __do_fault+0x256/0x3e5
[ 146.195916] [<ffffffff81068c42>] ? register_lock_class+0x1e/0x2d3
[ 146.195921] [<ffffffff810a5c05>] ? trace_preempt_on+0x15/0x28
[ 146.195925] [<ffffffff810d5755>] ? __do_fault+0x34c/0x3e5
[ 146.195931] [<ffffffff8155adbc>] ? _raw_spin_unlock+0x30/0x69
[ 146.195935] [<ffffffff8106a45e>] ? mark_lock+0x2d/0x1d8
[ 146.195940] [<ffffffff810ba69c>] ? unlock_page+0x25/0x2a
[ 146.195944] [<ffffffff8106ab57>] ? __lock_acquire+0x54e/0xd4e
[ 146.195948] [<ffffffff810d790d>] ? handle_mm_fault+0x193/0x7c3
[ 146.195953] [<ffffffff8104acaa>] ? sigprocmask+0x2f/0xc5
[ 146.195957] [<ffffffff8104acaa>] ? sigprocmask+0x2f/0xc5
[ 146.195962] [<ffffffff810d4cc0>] ? might_fault+0x4e/0x9e
[ 146.195966] [<ffffffff8155aea0>] ? _raw_spin_unlock_irq+0x2b/0x70
[ 146.195970] [<ffffffff810a5c05>] ? trace_preempt_on+0x15/0x28
[ 146.195974] [<ffffffff8104ad35>] ? sigprocmask+0xba/0xc5
[ 146.195978] [<ffffffff8155aeab>] ? _raw_spin_unlock_irq+0x36/0x70
[ 146.195983] [<ffffffff8155e378>] ? sub_preempt_count+0x35/0x49
[ 146.195987] [<ffffffff8155aed7>] ? _raw_spin_unlock_irq+0x62/0x70
[ 146.195992] [<ffffffff8110a973>] sys_ppoll+0xd3/0x13c
[ 146.195996] [<ffffffff8106bc89>] ? trace_hardirqs_on_caller+0x117/0x13b
[ 146.196087] [<ffffffff8155a60b>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 146.196094] [<ffffffff8100277b>] system_call_fastpath+0x16/0x1b
On Thu, Nov 25, 2010 at 2:18 PM, <[email protected]> wrote:
> (Appears to have been present in -rc2-mmotm1117 as well, and maybe earlier. I
> suspect mcelog wasn't getting run at boot due to my fighting with systemd, so I
> didn't see it).
>
> [ 146.195836] ===================================================
> [ 146.195839] [ INFO: suspicious rcu_dereference_check() usage. ]
> [ 146.195841] ---------------------------------------------------
> [ 146.195844] arch/x86/kernel/cpu/mcheck/mce.c:1628 invoked rcu_dereference_check() without protection!
The warning comes from the rcu_dereference_check_mce() in mce_poll().
It seems that we do not need rcu_dereference_check_mce() here. Because
we only check the value of mcelog.next, but do not use that value to
access the content of the array.
Best Regards,
Huang Ying
> [ 146.195847]
> [ 146.195847] other info that might help us debug this:
> [ 146.195848]
> [ 146.195850]
> [ 146.195850] rcu_scheduler_active = 1, debug_locks = 1
> [ 146.195853] no locks held by mcelog/3806.
> [ 146.195855]
> [ 146.195855] stack backtrace:
> [ 146.195858] Pid: 3806, comm: mcelog Tainted: G W 2.6.37-rc3-mmotm1123 #4
> [ 146.195860] Call Trace:
> [ 146.195869] [<ffffffff81069538>] lockdep_rcu_dereference+0x9d/0xa5
> [ 146.195875] [<ffffffff810139ea>] mce_poll+0x66/0x74
> [ 146.195880] [<ffffffff8110a62e>] do_sys_poll+0x23b/0x3a5
> [ 146.195885] [<ffffffff811095ad>] ? __pollwait+0x0/0xc7
> [ 146.195889] [<ffffffff81109674>] ? pollwake+0x0/0x4f
> [ 146.195893] [<ffffffff81109674>] ? pollwake+0x0/0x4f
> [ 146.195898] [<ffffffff81094c0e>] ? __rcu_read_unlock+0x28f/0x2ab
> [ 146.195903] [<ffffffff810d565f>] ? __do_fault+0x256/0x3e5
> [ 146.195908] [<ffffffff81068775>] ? look_up_lock_class+0x5f/0xc4
> [ 146.195912] [<ffffffff810d565f>] ? __do_fault+0x256/0x3e5
> [ 146.195916] [<ffffffff81068c42>] ? register_lock_class+0x1e/0x2d3
> [ 146.195921] [<ffffffff810a5c05>] ? trace_preempt_on+0x15/0x28
> [ 146.195925] [<ffffffff810d5755>] ? __do_fault+0x34c/0x3e5
> [ 146.195931] [<ffffffff8155adbc>] ? _raw_spin_unlock+0x30/0x69
> [ 146.195935] [<ffffffff8106a45e>] ? mark_lock+0x2d/0x1d8
> [ 146.195940] [<ffffffff810ba69c>] ? unlock_page+0x25/0x2a
> [ 146.195944] [<ffffffff8106ab57>] ? __lock_acquire+0x54e/0xd4e
> [ 146.195948] [<ffffffff810d790d>] ? handle_mm_fault+0x193/0x7c3
> [ 146.195953] [<ffffffff8104acaa>] ? sigprocmask+0x2f/0xc5
> [ 146.195957] [<ffffffff8104acaa>] ? sigprocmask+0x2f/0xc5
> [ 146.195962] [<ffffffff810d4cc0>] ? might_fault+0x4e/0x9e
> [ 146.195966] [<ffffffff8155aea0>] ? _raw_spin_unlock_irq+0x2b/0x70
> [ 146.195970] [<ffffffff810a5c05>] ? trace_preempt_on+0x15/0x28
> [ 146.195974] [<ffffffff8104ad35>] ? sigprocmask+0xba/0xc5
> [ 146.195978] [<ffffffff8155aeab>] ? _raw_spin_unlock_irq+0x36/0x70
> [ 146.195983] [<ffffffff8155e378>] ? sub_preempt_count+0x35/0x49
> [ 146.195987] [<ffffffff8155aed7>] ? _raw_spin_unlock_irq+0x62/0x70
> [ 146.195992] [<ffffffff8110a973>] sys_ppoll+0xd3/0x13c
> [ 146.195996] [<ffffffff8106bc89>] ? trace_hardirqs_on_caller+0x117/0x13b
> [ 146.196087] [<ffffffff8155a60b>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [ 146.196094] [<ffffffff8100277b>] system_call_fastpath+0x16/0x1b
>
>