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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
arch Drivers: hv: vmbus: Get rid of MSR access from vmbus_drv.c 2018-07-29 08:09:56 +02:00
block for-linus-20180713 2018-07-14 12:28:00 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
Documentation Drivers: hv: vmbus: add numa_node to sysfs 2018-07-29 08:09:56 +02:00
drivers uio: fix possible circular locking dependency 2018-08-02 10:14:26 +02:00
firmware
fs reiserfs: fix buffer overflow with long warning messages 2018-07-14 11:11:10 -07:00
include Last round of FSI updates for 4.19 2018-07-27 10:37:08 +02:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-13 13:36:36 -07:00
lib This adds support for offloading the FSI low level bitbanging to the 2018-07-24 08:00:13 +02:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm Merge branch 'akpm' (patches from Andrew) 2018-07-14 11:14:33 -07:00
net net/9p/client.c: put refcount of trans_mod in error case in parse_opts() 2018-07-14 11:11:09 -07:00
samples sample: vfio-mdev: avoid deadlock in mdev_access() 2018-07-11 13:22:41 -06:00
scripts Merge 4.18-rc5 into char-misc-next 2018-07-16 09:04:54 +02:00
security selinux/stable-4.18 PR 20180629 2018-06-30 11:15:12 -07:00
sound ALSA: hda/ca0132: Update a pci quirk device name 2018-07-12 09:18:31 +02:00
tools Merge 4.18-rc5 into char-misc-next 2018-07-16 09:04:54 +02:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM: arm64: Prevent KVM_COMPAT from being selected 2018-06-21 17:17:50 +01:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Merge 4.18-rc5 into char-misc-next 2018-07-16 09:04:54 +02:00
Makefile Linux 4.18-rc5 2018-07-15 12:49:31 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.