* Christoph Mathys | 2015-12-21 10:49:41 [+0100]:
>When testing on another computer I got a BUG from the same general area:
If you can reproduce this then the following patch should fix it:
---
Subject: [PATCH] kernel/rcu: use swait for sync_rcu_preempt_exp_wq
__schedule() invokes rcu_note_context_switch() with preemption disabled:
|BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
|in_atomic(): 1, irqs_disabled(): 0, pid: 3329, name: init
|2 locks held by init/3329:
| #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8103f17e>] __do_page_fault+0x12e/0x5f0
| #1: (ptlock_ptr(page)#2){+.+...}, at: [<ffffffff8117235f>] do_read_fault.isra.66+0xaf/0x2d0
|CPU: 1 PID: 3329 Comm: init Tainted: G E 3.18.24-realtime-1-rt22 #1
|Call Trace:
| [<ffffffff81751b44>] rt_spin_lock+0x24/0x60
| [<ffffffff81093349>] __wake_up+0x29/0x60
| [<ffffffff810bcd04>] rcu_report_exp_rnp.isra.64+0xb4/0xc0
| [<ffffffff810c0a9b>] rcu_read_unlock_special+0x1fb/0x250
| [<ffffffff810c0cd4>] rcu_note_context_switch+0x1e4/0x420
| [<ffffffff8174d7c6>] __schedule+0x56/0x8a0
| [<ffffffff8174e4b4>] preempt_schedule_irq+0x44/0x80
| [<ffffffff81753883>] check_int_off+0x11/0x1e
| [<ffffffff81143848>] filemap_map_pages+0x188/0x270
| [<ffffffff8117246a>] do_read_fault.isra.66+0x1ba/0x2d0
| [<ffffffff81173abf>] handle_mm_fault+0x5ef/0xec0
| [<ffffffff8103f1e2>] __do_page_fault+0x192/0x5f0
| [<ffffffff8103f64c>] do_page_fault+0xc/0x10
| [<ffffffff81754752>] page_fault+0x22/0x30
| [<ffffffff811c7a75>] getname_flags+0xb5/0x1a0
| [<ffffffff811c7b72>] getname+0x12/0x20
| [<ffffffff811b594d>] do_sys_open+0xfd/0x220
| [<ffffffff8109e44d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
| [<ffffffff811b5a8e>] SyS_open+0x1e/0x20
| [<ffffffff81752976>] system_call_fastpath+0x16/0x1b
Reported-by: Christoph Mathys <eraserix@xxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 54da8f44d586..1cbeb0aa79e2 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -527,7 +527,7 @@ void synchronize_rcu(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
-static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
+static DEFINE_SWAIT_HEAD(sync_rcu_preempt_exp_wq);
static unsigned long sync_rcu_preempt_exp_count;
static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
@@ -584,7 +584,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
raw_spin_unlock_irqrestore(&rnp->lock, flags);
if (wake) {
smp_mb(); /* EGP done before wake_up(). */
- wake_up(&sync_rcu_preempt_exp_wq);
+ swait_wake(&sync_rcu_preempt_exp_wq);
}
break;
}
@@ -759,7 +759,7 @@ void synchronize_rcu_expedited(void)
/* Wait for snapshotted ->blkd_tasks lists to drain. */
rnp = rcu_get_root(rsp);
- wait_event(sync_rcu_preempt_exp_wq,
+ swait_event(sync_rcu_preempt_exp_wq,
sync_rcu_preempt_exp_done(rnp));
/* Clean up and exit. */
--
2.6.4
Sebastian
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