linux/drivers/uio
Xiubo Li b34e9a15b3 uio: fix possible circular locking dependency
The call trace:
XXX/1910 is trying to acquire lock:
 (&mm->mmap_sem){++++++}, at: [<ffffffff97008c87>] might_fault+0x57/0xb0

but task is already holding lock:
 (&idev->info_lock){+.+...}, at: [<ffffffffc0638a06>] uio_write+0x46/0x130 [uio]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&idev->info_lock){+.+...}:
       [<ffffffff96f31fc9>] lock_acquire+0x99/0x1e0
       [<ffffffff975edad3>] mutex_lock_nested+0x93/0x410
       [<ffffffffc063873d>] uio_mmap+0x2d/0x170 [uio]
       [<ffffffff97016b58>] mmap_region+0x428/0x650
       [<ffffffff97017138>] do_mmap+0x3b8/0x4e0
       [<ffffffff96ffaba3>] vm_mmap_pgoff+0xd3/0x120
       [<ffffffff97015261>] SyS_mmap_pgoff+0x1f1/0x270
       [<ffffffff96e387c2>] SyS_mmap+0x22/0x30
       [<ffffffff975ff315>] system_call_fastpath+0x1c/0x21

-> #0 (&mm->mmap_sem){++++++}:
       [<ffffffff96f30e9c>] __lock_acquire+0xdac/0x15f0
       [<ffffffff96f31fc9>] lock_acquire+0x99/0x1e0
       [<ffffffff97008cb4>] might_fault+0x84/0xb0
       [<ffffffffc0638a74>] uio_write+0xb4/0x130 [uio]
       [<ffffffff9706ffa3>] vfs_write+0xc3/0x1f0
       [<ffffffff97070e2a>] SyS_write+0x8a/0x100
       [<ffffffff975ff315>] system_call_fastpath+0x1c/0x21

other info that might help us debug this:
 Possible unsafe locking scenario:
       CPU0                    CPU1
       ----                    ----
  lock(&idev->info_lock);
                               lock(&mm->mmap_sem);
                               lock(&idev->info_lock);
  lock(&mm->mmap_sem);

 *** DEADLOCK ***
1 lock held by XXX/1910:
 #0:  (&idev->info_lock){+.+...}, at: [<ffffffffc0638a06>] uio_write+0x46/0x130 [uio]

stack backtrace:
CPU: 0 PID: 1910 Comm: XXX Kdump: loaded Not tainted #1
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
Call Trace:
 [<ffffffff975e9211>] dump_stack+0x19/0x1b
 [<ffffffff975e260a>] print_circular_bug+0x1f9/0x207
 [<ffffffff96f2f6a7>] check_prevs_add+0x957/0x960
 [<ffffffff96f30e9c>] __lock_acquire+0xdac/0x15f0
 [<ffffffff96f2fb19>] ? mark_held_locks+0xb9/0x140
 [<ffffffff96f31fc9>] lock_acquire+0x99/0x1e0
 [<ffffffff97008c87>] ? might_fault+0x57/0xb0
 [<ffffffff97008cb4>] might_fault+0x84/0xb0
 [<ffffffff97008c87>] ? might_fault+0x57/0xb0
 [<ffffffffc0638a74>] uio_write+0xb4/0x130 [uio]
 [<ffffffff9706ffa3>] vfs_write+0xc3/0x1f0
 [<ffffffff9709349c>] ? fget_light+0xfc/0x510
 [<ffffffff97070e2a>] SyS_write+0x8a/0x100
 [<ffffffff975ff315>] system_call_fastpath+0x1c/0x21

Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-02 10:14:26 +02:00
..
Kconfig uio-hv-generic: new userspace i/o driver for VMBus 2016-12-06 11:52:49 +01:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
uio_aec.c uio: uio_aec: remove unnecessary pci_set_drvdata() 2013-09-26 08:47:25 -07:00
uio_cif.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio_dmem_genirq.c uio: fix dmem_region_start computation 2016-08-31 13:07:30 +02:00
uio_fsl_elbc_gpcm.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio_hv_generic.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio_mf624.c uio_mf624: Align memory regions to page size and set correct offsets 2017-04-08 18:13:28 +02:00
uio_netx.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio_pci_generic.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio_pdrv_genirq.c Revert "uio: constify of_device_id array" 2015-04-03 16:04:21 +02:00
uio_pruss.c uio: pruss: fix error handling in probe 2018-08-02 10:14:26 +02:00
uio_sercos3.c uio: add SPDX license tags 2018-07-21 15:41:20 +02:00
uio.c uio: fix possible circular locking dependency 2018-08-02 10:14:26 +02:00