Greetings,
Here is an rfcomm error triggered by this debug check.
git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/wait
commit 64c2181bc433b17f04da8fe8592aa83cceac9606
Author: Peter Zijlstra <pet...@infradead.org>
AuthorDate: Mon Aug 4 11:14:16 2014 +0200
Commit: Peter Zijlstra <a.p.zijls...@chello.nl>
CommitDate: Mon Aug 4 13:29:59 2014 +0200
sched: Debug nested sleeps
Validate we call might_sleep() with TASK_RUNNING, which catches places
where we nest blocking primitives, eg. mutex usage in a wait loop.
Since all blocking is arranged through task_struct::state, nesting
this is going to cause two distinct issues:
- the inner primitive will set TASK_RUNNING and the outer will not
block
- the outer sets !TASK_RUNNING and the inner expects to be called
with TASK_RUNNING and blocks forever (mutex_lock).
Signed-off-by: Peter Zijlstra <pet...@infradead.org>
Link: http://lkml.kernel.org/n/tip-0hge361rozfbng4z2t64t...@git.kernel.org
[ 4.595230] mpoa:atm_mpoa_init: mpc.c: initialized
[ 4.595625] 8021q: 802.1Q VLAN Support v1.8
[ 4.596034] ------------[ cut here ]------------
[ 4.596422] WARNING: CPU: 0 PID: 105 at kernel/sched/core.c:7094
__might_sleep+0x286/0x320()
[ 4.597287] do not call blocking ops when !TASK_RUNNING; state=1 set at
[<c21183b0>] rfcomm_run+0x160/0x27a0
[ 4.598083] CPU: 0 PID: 105 Comm: krfcommd Not tainted 3.16.0-00053-g64c2181
#1
[ 4.598668] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 4.599133] c25eb548 d16ebe30 c236754c d16ebe60 c106fa44 c25eb644 d16ebe8c
00000069
[ 4.599857] c25eb548 00001bb6 c10b9b16 c10b9b16 d16bd810 c25ebd04 00000067
d16ebe78
[ 4.600595] c106fb3a 00000009 d16ebe70 c25eb644 d16ebe8c d16ebea8 c10b9b16
c25eb548
[ 4.601320] Call Trace:
[ 4.601531] [<c236754c>] dump_stack+0x40/0x5e
[ 4.601900] [<c106fa44>] warn_slowpath_common+0xc4/0x110
[ 4.602337] [<c10b9b16>] ? __might_sleep+0x286/0x320
[ 4.602752] [<c10b9b16>] ? __might_sleep+0x286/0x320
[ 4.603158] [<c106fb3a>] warn_slowpath_fmt+0x4a/0x60
[ 4.603581] [<c10b9b16>] __might_sleep+0x286/0x320
[ 4.603988] [<c21183b0>] ? rfcomm_run+0x160/0x27a0
[ 4.604384] [<c21183b0>] ? rfcomm_run+0x160/0x27a0
[ 4.604786] [<c2118250>] ? rfcomm_check_accept+0x130/0x130
[ 4.605241] [<c23794c5>] mutex_lock+0x25/0x60
[ 4.605604] [<c2118412>] rfcomm_run+0x1c2/0x27a0
[ 4.605993] [<c10bd9bd>] ? pick_next_task_fair+0x12d/0x260
[ 4.606441] [<c237b7e1>] ? _raw_spin_unlock_irq+0x71/0xc0
[ 4.606925] [<c237229d>] ? __schedule+0x48d/0xb60
[ 4.607316] [<c237b6db>] ? _raw_spin_unlock_irqrestore+0x7b/0x110
[ 4.607819] [<c2372c69>] ? preempt_schedule+0x69/0xf0
[ 4.608241] [<c1013800>] ? ___preempt_schedule+0xc/0x1c
[ 4.608667] [<c237b700>] ? _raw_spin_unlock_irqrestore+0xa0/0x110
[ 4.609170] [<c2118250>] ? rfcomm_check_accept+0x130/0x130
[ 4.609624] [<c10a4258>] kthread+0x118/0x160
[ 4.609987] [<c237cac0>] ret_from_kernel_thread+0x20/0x30
[ 4.610443] [<c10a4140>] ? __kthread_unpark+0xa0/0xa0
[ 4.610873] ---[ end trace 123887810d830305 ]---
[ 4.611251] ------------[ cut here ]------------
This script may reproduce the error.
----------------------------------------------------------------------------
#!/bin/bash
kernel=$1
initrd=yocto-minimal-i386.cgz
wget --no-clobber
https://github.com/fengguang/reproduce-kernel-bug/raw/master/initrd/$initrd
kvm=(
qemu-system-x86_64
-cpu kvm64
-enable-kvm
-kernel $kernel
-initrd $initrd
-m 320
-smp 1
-net nic,vlan=1,model=e1000
-net user,vlan=1
-boot order=nc
-no-reboot
-watchdog i6300esb
-rtc base=localtime
-serial stdio
-display none
-monitor null
)
append=(
hung_task_panic=1
earlyprintk=ttyS0,115200
debug
apic=debug
sysrq_always_enabled
rcupdate.rcu_cpu_stall_timeout=100
panic=10
softlockup_panic=1
nmi_watchdog=panic
load_ramdisk=2
prompt_ramdisk=0
console=ttyS0,115200
console=tty0
vga=normal
root=/dev/ram0
rw
drbd.minor_count=8
)
"${kvm[@]}" --append "${append[*]}"
----------------------------------------------------------------------------
Thanks,
Fengguang
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