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58a89ecaca
ppp_dev_uninit() locks all_ppp_mutex while under rtnl mutex protection.
ppp_create_interface() must then lock these mutexes in that same order
to avoid possible deadlock.
[ 120.880011] ======================================================
[ 120.880011] [ INFO: possible circular locking dependency detected ]
[ 120.880011] 4.2.0 #1 Not tainted
[ 120.880011] -------------------------------------------------------
[ 120.880011] ppp-apitest/15827 is trying to acquire lock:
[ 120.880011] (&pn->all_ppp_mutex){+.+.+.}, at: [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic]
[ 120.880011]
[ 120.880011] but task is already holding lock:
[ 120.880011] (rtnl_mutex){+.+.+.}, at: [<ffffffff812e4255>] rtnl_lock+0x12/0x14
[ 120.880011]
[ 120.880011] which lock already depends on the new lock.
[ 120.880011]
[ 120.880011]
[ 120.880011] the existing dependency chain (in reverse order) is:
[ 120.880011]
[ 120.880011] -> #1 (rtnl_mutex){+.+.+.}:
[ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e
[ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341
[ 120.880011] [<ffffffff812e4255>] rtnl_lock+0x12/0x14
[ 120.880011] [<ffffffff812d9d94>] register_netdev+0x11/0x27
[ 120.880011] [<ffffffffa0147b17>] ppp_ioctl+0x289/0xc98 [ppp_generic]
[ 120.880011] [<ffffffff8113b367>] do_vfs_ioctl+0x4ea/0x532
[ 120.880011] [<ffffffff8113b3fd>] SyS_ioctl+0x4e/0x7d
[ 120.880011] [<ffffffff813ad7d7>] entry_SYSCALL_64_fastpath+0x12/0x6f
[ 120.880011]
[ 120.880011] -> #0 (&pn->all_ppp_mutex){+.+.+.}:
[ 120.880011] [<ffffffff8107334e>] __lock_acquire+0xb07/0xe76
[ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e
[ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341
[ 120.880011] [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic]
[ 120.880011] [<ffffffff812d5263>] rollback_registered_many+0x19e/0x252
[ 120.880011] [<ffffffff812d5381>] rollback_registered+0x29/0x38
[ 120.880011] [<ffffffff812d53fa>] unregister_netdevice_queue+0x6a/0x77
[ 120.880011] [<ffffffffa0146a94>] ppp_release+0x42/0x79 [ppp_generic]
[ 120.880011] [<ffffffff8112d9f6>] __fput+0xec/0x192
[ 120.880011] [<ffffffff8112dacc>] ____fput+0x9/0xb
[ 120.880011] [<ffffffff8105447a>] task_work_run+0x66/0x80
[ 120.880011] [<ffffffff81001801>] prepare_exit_to_usermode+0x8c/0xa7
[ 120.880011] [<ffffffff81001900>] syscall_return_slowpath+0xe4/0x104
[ 120.880011] [<ffffffff813ad931>] int_ret_from_sys_call+0x25/0x9f
[ 120.880011]
[ 120.880011] other info that might help us debug this:
[ 120.880011]
[ 120.880011] Possible unsafe locking scenario:
[ 120.880011]
[ 120.880011] CPU0 CPU1
[ 120.880011] ---- ----
[ 120.880011] lock(rtnl_mutex);
[ 120.880011] lock(&pn->all_ppp_mutex);
[ 120.880011] lock(rtnl_mutex);
[ 120.880011] lock(&pn->all_ppp_mutex);
[ 120.880011]
[ 120.880011] *** DEADLOCK ***
Fixes:
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.. | ||
accessibility | ||
acpi | ||
amba | ||
android | ||
ata | ||
atm | ||
auxdisplay | ||
base | ||
bcma | ||
block | ||
bluetooth | ||
bus | ||
cdrom | ||
char | ||
clk | ||
clocksource | ||
connector | ||
cpufreq | ||
cpuidle | ||
crypto | ||
dca | ||
devfreq | ||
dio | ||
dma | ||
dma-buf | ||
edac | ||
eisa | ||
extcon | ||
firewire | ||
firmware | ||
fmc | ||
gpio | ||
gpu | ||
hid | ||
hsi | ||
hv | ||
hwmon | ||
hwspinlock | ||
hwtracing/coresight | ||
i2c | ||
ide | ||
idle | ||
iio | ||
infiniband | ||
input | ||
iommu | ||
ipack | ||
irqchip | ||
isdn | ||
leds | ||
lguest | ||
macintosh | ||
mailbox | ||
mcb | ||
md | ||
media | ||
memory | ||
memstick | ||
message | ||
mfd | ||
misc | ||
mmc | ||
mtd | ||
net | ||
nfc | ||
ntb | ||
nubus | ||
nvdimm | ||
nvmem | ||
of | ||
oprofile | ||
parisc | ||
parport | ||
pci | ||
pcmcia | ||
perf | ||
phy | ||
pinctrl | ||
platform | ||
pnp | ||
power | ||
powercap | ||
pps | ||
ps3 | ||
ptp | ||
pwm | ||
rapidio | ||
ras | ||
regulator | ||
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reset | ||
rpmsg | ||
rtc | ||
s390 | ||
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sh | ||
sn | ||
soc | ||
spi | ||
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tty | ||
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usb | ||
uwb | ||
vfio | ||
vhost | ||
video | ||
virt | ||
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vlynq | ||
vme | ||
w1 | ||
watchdog | ||
xen | ||
zorro | ||
Kconfig | ||
Makefile |