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linux-next/drivers
Hans Verkuil e752577ed7 [media] v4l2-mem2mem: drop lock in v4l2_m2m_fop_mmap
The v4l2_m2m_fop_mmap function takes the core mutex, but this will result in a potential
circular locking dependency:

[  262.517164] ======================================================
[  262.517166] [ INFO: possible circular locking dependency detected ]
[  262.517169] 4.2.0-rc2-koryphon #844 Not tainted
[  262.517171] -------------------------------------------------------
[  262.517173] v4l2-compliance/1379 is trying to acquire lock:
[  262.517175]  (&dev->dev_mutex){+.+.+.}, at: [<ffffffffa000ddab>] v4l2_m2m_fop_mmap+0x2b/0x90 [v4l2_mem2mem]
[  262.517187]
               but task is already holding lock:
[  262.517189]  (&mm->mmap_sem){++++++}, at: [<ffffffff81159309>] vm_mmap_pgoff+0x69/0xc0
[  262.517199]
               which lock already depends on the new lock.

[  262.517202]
               the existing dependency chain (in reverse order) is:
[  262.517204]
               -> #1 (&mm->mmap_sem){++++++}:
[  262.517209]        [<ffffffff810d0e6b>] __lock_acquire+0x62b/0xe80
[  262.517215]        [<ffffffff810d2095>] lock_acquire+0x65/0x90
[  262.517218]        [<ffffffff811612e5>] __might_fault+0x75/0xa0
[  262.517222]        [<ffffffffa06dead9>] video_usercopy+0x3e9/0x4e0 [videodev]
[  262.517231]        [<ffffffffa06debe0>] video_ioctl2+0x10/0x20 [videodev]
[  262.517238]        [<ffffffffa06d8663>] v4l2_ioctl+0xc3/0xe0 [videodev]
[  262.517243]        [<ffffffff811a8cac>] do_vfs_ioctl+0x2fc/0x550
[  262.517248]        [<ffffffff811a8f74>] SyS_ioctl+0x74/0x80
[  262.517252]        [<ffffffff81a4d2ee>] entry_SYSCALL_64_fastpath+0x12/0x76
[  262.517258]
               -> #0 (&dev->dev_mutex){+.+.+.}:
[  262.517262]        [<ffffffff810cf464>] validate_chain.isra.38+0xd04/0x1170
[  262.517266]        [<ffffffff810d0e6b>] __lock_acquire+0x62b/0xe80
[  262.517270]        [<ffffffff810d2095>] lock_acquire+0x65/0x90
[  262.517273]        [<ffffffff81a48e3c>] mutex_lock_interruptible_nested+0x6c/0x4b0
[  262.517279]        [<ffffffffa000ddab>] v4l2_m2m_fop_mmap+0x2b/0x90 [v4l2_mem2mem]
[  262.517284]        [<ffffffffa06d80ff>] v4l2_mmap+0x4f/0x90 [videodev]
[  262.517288]        [<ffffffff8116b06c>] mmap_region+0x38c/0x5b0
[  262.517293]        [<ffffffff8116b585>] do_mmap_pgoff+0x2f5/0x3e0
[  262.517297]        [<ffffffff8115932a>] vm_mmap_pgoff+0x8a/0xc0
[  262.517300]        [<ffffffff81169bab>] SyS_mmap_pgoff+0x1cb/0x270
[  262.517304]        [<ffffffff8100876d>] SyS_mmap+0x1d/0x20
[  262.517309]        [<ffffffff81a4d2ee>] entry_SYSCALL_64_fastpath+0x12/0x76
[  262.517313]
               other info that might help us debug this:

[  262.517315]  Possible unsafe locking scenario:

[  262.517318]        CPU0                    CPU1
[  262.517319]        ----                    ----
[  262.517321]   lock(&mm->mmap_sem);
[  262.517324]                                lock(&dev->dev_mutex);
[  262.517327]                                lock(&mm->mmap_sem);
[  262.517329]   lock(&dev->dev_mutex);
[  262.517332]
                *** DEADLOCK ***

Since vb2_fop_mmap doesn't take the lock, neither should v4l2_m2m_fop_mmap.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Mikhail Ulyanov <mikhail.ulyanov@cogentembedded.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
2015-08-11 06:37:23 -03:00
..
accessibility
acpi Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm 2015-07-11 20:44:31 -07:00
amba
android
ata ata: ahci_platform: Add ACPI _CLS matching 2015-07-07 01:55:21 +02:00
atm
auxdisplay
base Fix firmware loader uevent buffer NULL pointer dereference 2015-07-09 11:20:01 -07:00
bcma
block Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
bluetooth Bluetooth: ath3k: Add support of 04ca:300d AR3012 device 2015-06-18 21:00:06 +03:00
bus ARM: SoC: driver updates for v4.2 2015-06-26 11:54:29 -07:00
cdrom
char Merge tag 'drm-intel-next-fixes-2015-07-02' of git://anongit.freedesktop.org/drm-intel 2015-07-02 14:36:40 -07:00
clk A small set of fixes for problems found by smatch in new drivers 2015-07-11 11:08:21 -07:00
clocksource clocksource/imx: Define clocksource for mx27 2015-07-07 10:44:45 +02:00
connector
cpufreq MIPS, CPUFREQ: Fix spelling of Institute. 2015-07-07 20:59:42 +02:00
cpuidle Replace module_platform_driver with builtin_platform driver in non modules. 2015-07-02 10:42:13 -07:00
crypto crypto: marvell/cesa - another fix up for of_get_named_gen_pool() rename 2015-07-03 11:37:02 -07:00
dca
devfreq
dio
dma Merge branch 'akpm' (patches from Andrew) 2015-07-01 17:47:51 -07:00
dma-buf
edac A build fix for octeon_edac from Aaro Koskinen. 2015-07-03 12:10:12 -07:00
eisa
extcon
firewire
firmware Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2015-07-03 15:20:57 -07:00
fmc
gpio Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-07-01 15:19:35 -07:00
gpu Revert "drm/i915: Use crtc_state->active in primary check_plane func" 2015-07-12 15:00:20 -07:00
hid Merge branches 'for-4.2/i2c-hid', 'for-4.2/lenovo', 'for-4.2/plantronics', 'for-4.2/rmi', 'for-4.2/sensor-hub', 'for-4.2/sjoy', 'for-4.2/sony' and 'for-4.2/wacom' into for-linus 2015-06-22 16:23:43 +02:00
hsi Fix up implicit <module.h> users that will break later. 2015-07-02 10:25:22 -07:00
hv
hwmon hwmon: (w83627ehf) Use swap() in w82627ehf_swap_tempreg() 2015-07-03 14:39:06 +02:00
hwspinlock hwspinlock: qcom: Correct msb in regmap_field 2015-07-01 16:15:05 +03:00
hwtracing/coresight
i2c i2c: Mark instantiated device nodes with OF_POPULATE 2015-07-09 22:25:54 +02:00
ide Minor merge needed, due to function move. 2015-07-01 10:49:25 -07:00
idle
iio
infiniband Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2015-07-11 11:16:04 -07:00
iommu IOMMU Fixes for Linux v4.2-rc0 2015-07-01 14:44:22 -07:00
ipack
irqchip Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-07-12 13:55:24 -07:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2015-06-24 16:49:49 -07:00
leds Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds 2015-07-01 19:09:11 -07:00
lguest Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
macintosh
mailbox Replace module_init with appropriate alternate initcall in non modules. 2015-07-02 10:36:29 -07:00
mcb
md Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
media [media] v4l2-mem2mem: drop lock in v4l2_m2m_fop_mmap 2015-08-11 06:37:23 -03:00
memory Merge branch 'fixes-rc1' into omap-for-v4.2/fixes 2015-07-06 05:33:17 -07:00
memstick memstick: remove deprecated use of pci api 2015-06-30 19:44:57 -07:00
message
mfd Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-07-01 15:19:35 -07:00
misc powerpc fixes for 4.2 2015-07-10 12:16:59 -07:00
mmc ARM: SoC: late fixes and dependencies 2015-07-02 14:40:49 -07:00
mtd Minor merge needed, due to function move. 2015-07-01 10:49:25 -07:00
net A very significant modification to NTB in this series. 2015-07-04 14:07:47 -07:00
nfc Char/Misc driver patches for 4.2-rc1 2015-06-26 14:51:15 -07:00
ntb NTB: Add split BAR output for debugfs stats 2015-07-04 14:09:32 -04:00
nubus
nvdimm nvdimm: Fix return value of nvdimm_bus_init() if class_create() fails 2015-06-30 14:30:34 -04:00
of Devicetree changes for v4.2 2015-07-01 19:40:18 -07:00
oprofile
parisc
parport
pci Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-07-01 15:19:35 -07:00
pcmcia Fix up implicit <module.h> users that will break later. 2015-07-02 10:25:22 -07:00
phy Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-06-27 12:44:34 -07:00
pinctrl Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-07-01 15:19:35 -07:00
platform platform-drivers-x86 for 4.2-2 2015-07-05 10:54:09 -07:00
pnp ACPI / PNP: Reserve ACPI resources at the fs_initcall_sync stage 2015-07-06 23:52:21 +02:00
power Replace module_platform_driver with builtin_platform driver in non modules. 2015-07-02 10:42:13 -07:00
powercap
pps
ps3
ptp
pwm pwm: Changes for v4.2-rc1 2015-06-23 13:32:38 -07:00
rapidio Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2015-06-23 14:08:54 -07:00
ras
regulator Fix up implicit <module.h> users that will break later. 2015-07-02 10:25:22 -07:00
remoteproc remoteproc: fix !CONFIG_OF build breakage 2015-06-18 11:44:41 +03:00
reset
rpmsg
rtc Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-06-27 12:44:34 -07:00
s390 KVM: s390: virtio-ccw: don't overwrite config space values 2015-07-03 18:55:18 +02:00
sbus
scsi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-07-04 14:13:43 -07:00
sfi
sh Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-07-01 15:19:35 -07:00
sn
soc ARM: SoC: late fixes and dependencies 2015-07-02 14:40:49 -07:00
spi
spmi
ssb
staging [media] staging: media: lirc: fix coding style error 2015-07-22 13:27:40 -03:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-07-04 14:13:43 -07:00
tc
thermal Minor merge needed, due to function move. 2015-07-01 10:49:25 -07:00
thunderbolt
tty ARM: SoC: late fixes and dependencies 2015-07-02 14:40:49 -07:00
uio
usb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
uwb
vfio VFIO updates for v4.2 2015-06-28 12:32:13 -07:00
vhost Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-07-04 14:13:43 -07:00
video stifb: Implement hardware accelerated copyarea 2015-07-10 21:44:19 +02:00
virt
virtio virtio/vhost: cross endian support 2015-07-03 16:02:25 -07:00
vlynq
vme
w1
watchdog Merge git://www.linux-watchdog.org/linux-watchdog 2015-07-01 19:33:16 -07:00
xen Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-07-04 14:13:43 -07:00
zorro
Kconfig libnvdimm, nfit: initial libnvdimm infrastructure and NFIT support 2015-06-24 21:24:10 -04:00
Makefile The libnvdimm sub-system introduces, in addition to the libnvdimm-core, 2015-06-29 10:34:42 -07:00