linux-stable.git/fs, branch v4.4.181

fuse: Add FOPEN_STREAM to use stream_open()

2019-06-11T10:24:13+00:00

commit bbd84f33652f852ce5992d65db4d020aba21f882 upstream.

Starting from commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per
POSIX") files opened even via nonseekable_open gate read and write via lock
and do not allow them to be run simultaneously. This can create read vs
write deadlock if a filesystem is trying to implement a socket-like file
which is intended to be simultaneously used for both read and write from
filesystem client.  See commit 10dce8af3422 ("fs: stream_open - opener for
stream-like files so that read and write can run simultaneously without
deadlock") for details and e.g. commit 581d21a2d02a ("xenbus: fix deadlock
on writes to /proc/xen/xenbus") for a similar deadlock example on
/proc/xen/xenbus.

To avoid such deadlock it was tempting to adjust fuse_finish_open to use
stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags,
but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE,
and in particular GVFS which actually uses offset in its read and write
handlers

	https://codesearch.debian.net/search?q=-%3Enonseekable+%3D
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481

so if we would do such a change it will break a real user.

Add another flag (FOPEN_STREAM) for filesystem servers to indicate that the
opened handler is having stream-like semantics; does not use file position
and thus the kernel is free to issue simultaneous read and write request on
opened file handle.

This patch together with stream_open() should be added to stable kernels
starting from v3.14+. This will allow to patch OSSPD and other FUSE
filesystems that provide stream-like files to return FOPEN_STREAM |
FOPEN_NONSEEKABLE in open handler and this way avoid the deadlock on all
kernel versions. This should work because fuse_finish_open ignores unknown
open flags returned from a filesystem and so passing FOPEN_STREAM to a
kernel that is not aware of this flag cannot hurt. In turn the kernel that
is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE
is sufficient to implement streams without read vs write deadlock.

Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Kirill Smelkov 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock

2019-06-11T10:24:13+00:00

commit 10dce8af34226d90fa56746a934f8da5dcdba3df upstream.

Commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") added
locking for file.f_pos access and in particular made concurrent read and
write not possible - now both those functions take f_pos lock for the
whole run, and so if e.g. a read is blocked waiting for data, write will
deadlock waiting for that read to complete.

This caused regression for stream-like files where previously read and
write could run simultaneously, but after that patch could not do so
anymore. See e.g. commit 581d21a2d02a ("xenbus: fix deadlock on writes
to /proc/xen/xenbus") which fixes such regression for particular case of
/proc/xen/xenbus.

The patch that added f_pos lock in 2014 did so to guarantee POSIX thread
safety for read/write/lseek and added the locking to file descriptors of
all regular files. In 2014 that thread-safety problem was not new as it
was already discussed earlier in 2006.

However even though 2006'th version of Linus's patch was adding f_pos
locking "only for files that are marked seekable with FMODE_LSEEK (thus
avoiding the stream-like objects like pipes and sockets)", the 2014
version - the one that actually made it into the tree as 9c225f2655e3 -
is doing so irregardless of whether a file is seekable or not.

See

    https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/
    https://lwn.net/Articles/180387
    https://lwn.net/Articles/180396

for historic context.

The reason that it did so is, probably, that there are many files that
are marked non-seekable, but e.g. their read implementation actually
depends on knowing current position to correctly handle the read. Some
examples:

	kernel/power/user.c		snapshot_read
	fs/debugfs/file.c		u32_array_read
	fs/fuse/control.c		fuse_conn_waiting_read + ...
	drivers/hwmon/asus_atk0110.c	atk_debugfs_ggrp_read
	arch/s390/hypfs/inode.c		hypfs_read_iter
	...

Despite that, many nonseekable_open users implement read and write with
pure stream semantics - they don't depend on passed ppos at all. And for
those cases where read could wait for something inside, it creates a
situation similar to xenbus - the write could be never made to go until
read is done, and read is waiting for some, potentially external, event,
for potentially unbounded time -> deadlock.

Besides xenbus, there are 14 such places in the kernel that I've found
with semantic patch (see below):

	drivers/xen/evtchn.c:667:8-24: ERROR: evtchn_fops: .read() can deadlock .write()
	drivers/isdn/capi/capi.c:963:8-24: ERROR: capi_fops: .read() can deadlock .write()
	drivers/input/evdev.c:527:1-17: ERROR: evdev_fops: .read() can deadlock .write()
	drivers/char/pcmcia/cm4000_cs.c:1685:7-23: ERROR: cm4000_fops: .read() can deadlock .write()
	net/rfkill/core.c:1146:8-24: ERROR: rfkill_fops: .read() can deadlock .write()
	drivers/s390/char/fs3270.c:488:1-17: ERROR: fs3270_fops: .read() can deadlock .write()
	drivers/usb/misc/ldusb.c:310:1-17: ERROR: ld_usb_fops: .read() can deadlock .write()
	drivers/hid/uhid.c:635:1-17: ERROR: uhid_fops: .read() can deadlock .write()
	net/batman-adv/icmp_socket.c:80:1-17: ERROR: batadv_fops: .read() can deadlock .write()
	drivers/media/rc/lirc_dev.c:198:1-17: ERROR: lirc_fops: .read() can deadlock .write()
	drivers/leds/uleds.c:77:1-17: ERROR: uleds_fops: .read() can deadlock .write()
	drivers/input/misc/uinput.c:400:1-17: ERROR: uinput_fops: .read() can deadlock .write()
	drivers/infiniband/core/user_mad.c:985:7-23: ERROR: umad_fops: .read() can deadlock .write()
	drivers/gnss/core.c:45:1-17: ERROR: gnss_fops: .read() can deadlock .write()

In addition to the cases above another regression caused by f_pos
locking is that now FUSE filesystems that implement open with
FOPEN_NONSEEKABLE flag, can no longer implement bidirectional
stream-like files - for the same reason as above e.g. read can deadlock
write locking on file.f_pos in the kernel.

FUSE's FOPEN_NONSEEKABLE was added in 2008 in a7c1b990f715 ("fuse:
implement nonseekable open") to support OSSPD. OSSPD implements /dev/dsp
in userspace with FOPEN_NONSEEKABLE flag, with corresponding read and
write routines not depending on current position at all, and with both
read and write being potentially blocking operations:

See

    https://github.com/libfuse/osspd
    https://lwn.net/Articles/308445

    https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1406
    https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1438-L1477
    https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1479-L1510

Corresponding libfuse example/test also describes FOPEN_NONSEEKABLE as
"somewhat pipe-like files ..." with read handler not using offset.
However that test implements only read without write and cannot exercise
the deadlock scenario:

    https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L124-L131
    https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L146-L163
    https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L209-L216

I've actually hit the read vs write deadlock for real while implementing
my FUSE filesystem where there is /head/watch file, for which open
creates separate bidirectional socket-like stream in between filesystem
and its user with both read and write being later performed
simultaneously. And there it is semantically not easy to split the
stream into two separate read-only and write-only channels:

    https://lab.nexedi.com/kirr/wendelin.core/blob/f13aa600/wcfs/wcfs.go#L88-169

Let's fix this regression. The plan is:

1. We can't change nonseekable_open to include &~FMODE_ATOMIC_POS -
   doing so would break many in-kernel nonseekable_open users which
   actually use ppos in read/write handlers.

2. Add stream_open() to kernel to open stream-like non-seekable file
   descriptors. Read and write on such file descriptors would never use
   nor change ppos. And with that property on stream-like files read and
   write will be running without taking f_pos lock - i.e. read and write
   could be running simultaneously.

3. With semantic patch search and convert to stream_open all in-kernel
   nonseekable_open users for which read and write actually do not
   depend on ppos and where there is no other methods in file_operations
   which assume @offset access.

4. Add FOPEN_STREAM to fs/fuse/ and open in-kernel file-descriptors via
   steam_open if that bit is present in filesystem open reply.

   It was tempting to change fs/fuse/ open handler to use stream_open
   instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but
   grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE,
   and in particular GVFS which actually uses offset in its read and
   write handlers

	https://codesearch.debian.net/search?q=-%3Enonseekable+%3D
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481

   so if we would do such a change it will break a real user.

5. Add stream_open and FOPEN_STREAM handling to stable kernels starting
   from v3.14+ (the kernel where 9c225f2655 first appeared).

   This will allow to patch OSSPD and other FUSE filesystems that
   provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE
   in their open handler and this way avoid the deadlock on all kernel
   versions. This should work because fs/fuse/ ignores unknown open
   flags returned from a filesystem and so passing FOPEN_STREAM to a
   kernel that is not aware of this flag cannot hurt. In turn the kernel
   that is not aware of FOPEN_STREAM will be < v3.14 where just
   FOPEN_NONSEEKABLE is sufficient to implement streams without read vs
   write deadlock.

This patch adds stream_open, converts /proc/xen/xenbus to it and adds
semantic patch to automatically locate in-kernel places that are either
required to be converted due to read vs write deadlock, or that are just
safe to be converted because read and write do not use ppos and there
are no other funky methods in file_operations.

Regarding semantic patch I've verified each generated change manually -
that it is correct to convert - and each other nonseekable_open instance
left - that it is either not correct to convert there, or that it is not
converted due to current stream_open.cocci limitations.

The script also does not convert files that should be valid to convert,
but that currently have .llseek = noop_llseek or generic_file_llseek for
unknown reason despite file being opened with nonseekable_open (e.g.
drivers/input/mousedev.c)

Cc: Michael Kerrisk 
Cc: Yongzhi Pan 
Cc: Jonathan Corbet 
Cc: David Vrabel 
Cc: Juergen Gross 
Cc: Miklos Szeredi 
Cc: Tejun Heo 
Cc: Kirill Tkhai 
Cc: Arnd Bergmann 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: Julia Lawall 
Cc: Nikolaus Rath 
Cc: Han-Wen Nienhuys 
[ backport to 4.4: actually fixed deadlock on /proc/xen/xenbus as 581d21a2d02a was not backported to 4.4 ]
Signed-off-by: Kirill Smelkov 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fuse: fallocate: fix return with locked inode

2019-06-11T10:24:13+00:00

commit 35d6fcbb7c3e296a52136347346a698a35af3fda upstream.

Do the proper cleanup in case the size check fails.

Tested with xfstests:generic/228

Reported-by: kbuild test robot 
Reported-by: Dan Carpenter 
Fixes: 0cbade024ba5 ("fuse: honor RLIMIT_FSIZE in fuse_file_fallocate")
Cc: Liu Bo 
Cc:  # v3.5
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

userfaultfd: don't pin the user memory in userfaultfd_file_create()

2019-06-11T10:24:11+00:00

commit d2005e3f41d4f9299e2df6a967c8beb5086967a9 upstream.

userfaultfd_file_create() increments mm->mm_users; this means that the
memory won't be unmapped/freed if mm owner exits/execs, and UFFDIO_COPY
after that can populate the orphaned mm more.

Change userfaultfd_file_create() and userfaultfd_ctx_put() to use
mm->mm_count to pin mm_struct.  This means that
atomic_inc_not_zero(mm->mm_users) is needed when we are going to
actually play with this memory.  Except handle_userfault() path doesn't
need this, the caller must already have a reference.

The patch adds the new trivial helper, mmget_not_zero(), it can have
more users.

Link: http://lkml.kernel.org/r/20160516172254.GA8595@redhat.com
Signed-off-by: Oleg Nesterov 
Cc: Andrea Arcangeli 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

CIFS: cifs_read_allocate_pages: don't iterate through whole page array on ENOMEM

2019-06-11T10:24:10+00:00

commit 31fad7d41e73731f05b8053d17078638cf850fa6 upstream.

 In cifs_read_allocate_pages, in case of ENOMEM, we go through
whole rdata->pages array but we have failed the allocation before
nr_pages, therefore we may end up calling put_page with NULL
pointer, causing oops

Signed-off-by: Roberto Bergantinos Corpas 
Acked-by: Pavel Shilovsky 
Signed-off-by: Steve French 
CC: Stable 
Signed-off-by: Greg Kroah-Hartman

Btrfs: fix race updating log root item during fsync

2019-06-11T10:24:09+00:00

commit 06989c799f04810f6876900d4760c0edda369cf7 upstream.

When syncing the log, the final phase of a fsync operation, we need to
either create a log root's item or update the existing item in the log
tree of log roots, and that depends on the current value of the log
root's log_transid - if it's 1 we need to create the log root item,
otherwise it must exist already and we update it. Since there is no
synchronization between updating the log_transid and checking it for
deciding whether the log root's item needs to be created or updated, we
end up with a tiny race window that results in attempts to update the
item to fail because the item was not yet created:

              CPU 1                                    CPU 2

  btrfs_sync_log()

    lock root->log_mutex

    set log root's log_transid to 1

    unlock root->log_mutex

                                               btrfs_sync_log()

                                                 lock root->log_mutex

                                                 sets log root's
                                                 log_transid to 2

                                                 unlock root->log_mutex

    update_log_root()

      sees log root's log_transid
      with a value of 2

        calls btrfs_update_root(),
        which fails with -EUCLEAN
        and causes transaction abort

Until recently the race lead to a BUG_ON at btrfs_update_root(), but after
the recent commit 7ac1e464c4d47 ("btrfs: Don't panic when we can't find a
root key") we just abort the current transaction.

A sample trace of the BUG_ON() on a SLE12 kernel:

  ------------[ cut here ]------------
  kernel BUG at ../fs/btrfs/root-tree.c:157!
  Oops: Exception in kernel mode, sig: 5 [#1]
  SMP NR_CPUS=2048 NUMA pSeries
  (...)
  Supported: Yes, External
  CPU: 78 PID: 76303 Comm: rtas_errd Tainted: G                 X 4.4.156-94.57-default #1
  task: c00000ffa906d010 ti: c00000ff42b08000 task.ti: c00000ff42b08000
  NIP: d000000036ae5cdc LR: d000000036ae5cd8 CTR: 0000000000000000
  REGS: c00000ff42b0b860 TRAP: 0700   Tainted: G                 X  (4.4.156-94.57-default)
  MSR: 8000000002029033   CR: 22444484  XER: 20000000
  CFAR: d000000036aba66c SOFTE: 1
  GPR00: d000000036ae5cd8 c00000ff42b0bae0 d000000036bda220 0000000000000054
  GPR04: 0000000000000001 0000000000000000 c00007ffff8d37c8 0000000000000000
  GPR08: c000000000e19c00 0000000000000000 0000000000000000 3736343438312079
  GPR12: 3930373337303434 c000000007a3a800 00000000007fffff 0000000000000023
  GPR16: c00000ffa9d26028 c00000ffa9d261f8 0000000000000010 c00000ffa9d2ab28
  GPR20: c00000ff42b0bc48 0000000000000001 c00000ff9f0d9888 0000000000000001
  GPR24: c00000ffa9d26000 c00000ffa9d261e8 c00000ffa9d2a800 c00000ff9f0d9888
  GPR28: c00000ffa9d26028 c00000ffa9d2aa98 0000000000000001 c00000ffa98f5b20
  NIP [d000000036ae5cdc] btrfs_update_root+0x25c/0x4e0 [btrfs]
  LR [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs]
  Call Trace:
  [c00000ff42b0bae0] [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs] (unreliable)
  [c00000ff42b0bba0] [d000000036b53610] btrfs_sync_log+0x2d0/0xc60 [btrfs]
  [c00000ff42b0bce0] [d000000036b1785c] btrfs_sync_file+0x44c/0x4e0 [btrfs]
  [c00000ff42b0bd80] [c00000000032e300] vfs_fsync_range+0x70/0x120
  [c00000ff42b0bdd0] [c00000000032e44c] do_fsync+0x5c/0xb0
  [c00000ff42b0be10] [c00000000032e8dc] SyS_fdatasync+0x2c/0x40
  [c00000ff42b0be30] [c000000000009488] system_call+0x3c/0x100
  Instruction dump:
  7f43d378 4bffebb9 60000000 88d90008 3d220000 e8b90000 3b390009 e87a01f0
  e8898e08 e8f90000 4bfd48e5 60000000 <0fe00000> e95b0060 39200004 394a0ea0
  ---[ end trace 8f2dc8f919cabab8 ]---

So fix this by doing the check of log_transid and updating or creating the
log root's item while holding the root's log_mutex.

Fixes: 7237f1833601d ("Btrfs: fix tree logs parallel sync")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana 
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

chardev: add additional check for minor range overlap

2019-06-11T10:24:03+00:00

[ Upstream commit de36e16d1557a0b6eb328bc3516359a12ba5c25c ]

Current overlap checking cannot correctly handle
a case which is baseminor < existing baseminor &&
baseminor + minorct > existing baseminor + minorct.

Signed-off-by: Chengguang Xu 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

gfs2: Fix lru_count going negative

2019-06-11T10:23:53+00:00

[ Upstream commit 7881ef3f33bb80f459ea6020d1e021fc524a6348 ]

Under certain conditions, lru_count may drop below zero resulting in
a large amount of log spam like this:

vmscan: shrink_slab: gfs2_dump_glock+0x3b0/0x630 [gfs2] \
    negative objects to delete nr=-1

This happens as follows:
1) A glock is moved from lru_list to the dispose list and lru_count is
   decremented.
2) The dispose function calls cond_resched() and drops the lru lock.
3) Another thread takes the lru lock and tries to add the same glock to
   lru_list, checking if the glock is on an lru list.
4) It is on a list (actually the dispose list) and so it avoids
   incrementing lru_count.
5) The glock is moved to lru_list.
5) The original thread doesn't dispose it because it has been re-added
   to the lru list but the lru_count has still decreased by one.

Fix by checking if the LRU flag is set on the glock rather than checking
if the glock is on some list and rearrange the code so that the LRU flag
is added/removed precisely when the glock is added/removed from lru_list.

Signed-off-by: Ross Lagerwall 
Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Sasha Levin

hugetlb: use same fault hash key for shared and private mappings

2019-06-11T10:23:52+00:00

commit 1b426bac66e6cc83c9f2d92b96e4e72acf43419a upstream.

hugetlb uses a fault mutex hash table to prevent page faults of the
same pages concurrently.  The key for shared and private mappings is
different.  Shared keys off address_space and file index.  Private keys
off mm and virtual address.  Consider a private mappings of a populated
hugetlbfs file.  A fault will map the page from the file and if needed
do a COW to map a writable page.

Hugetlbfs hole punch uses the fault mutex to prevent mappings of file
pages.  It uses the address_space file index key.  However, private
mappings will use a different key and could race with this code to map
the file page.  This causes problems (BUG) for the page cache remove
code as it expects the page to be unmapped.  A sample stack is:

page dumped because: VM_BUG_ON_PAGE(page_mapped(page))
kernel BUG at mm/filemap.c:169!
...
RIP: 0010:unaccount_page_cache_page+0x1b8/0x200
...
Call Trace:
__delete_from_page_cache+0x39/0x220
delete_from_page_cache+0x45/0x70
remove_inode_hugepages+0x13c/0x380
? __add_to_page_cache_locked+0x162/0x380
hugetlbfs_fallocate+0x403/0x540
? _cond_resched+0x15/0x30
? __inode_security_revalidate+0x5d/0x70
? selinux_file_permission+0x100/0x130
vfs_fallocate+0x13f/0x270
ksys_fallocate+0x3c/0x80
__x64_sys_fallocate+0x1a/0x20
do_syscall_64+0x5b/0x180
entry_SYSCALL_64_after_hwframe+0x44/0xa9

There seems to be another potential COW issue/race with this approach
of different private and shared keys as noted in commit 8382d914ebf7
("mm, hugetlb: improve page-fault scalability").

Since every hugetlb mapping (even anon and private) is actually a file
mapping, just use the address_space index key for all mappings.  This
results in potentially more hash collisions.  However, this should not
be the common case.

Link: http://lkml.kernel.org/r/20190328234704.27083-3-mike.kravetz@oracle.com
Link: http://lkml.kernel.org/r/20190412165235.t4sscoujczfhuiyt@linux-r8p5
Fixes: b5cec28d36f5 ("hugetlbfs: truncate_hugepages() takes a range of pages")
Signed-off-by: Mike Kravetz 
Reviewed-by: Naoya Horiguchi 
Reviewed-by: Davidlohr Bueso 
Cc: Joonsoo Kim 
Cc: "Kirill A . Shutemov" 
Cc: Michal Hocko 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

btrfs: sysfs: don't leak memory when failing add fsid

2019-06-11T10:23:52+00:00

commit e32773357d5cc271b1d23550b3ed026eb5c2a468 upstream.

A failed call to kobject_init_and_add() must be followed by a call to
kobject_put().  Currently in the error path when adding fs_devices we
are missing this call.  This could be fixed by calling
btrfs_sysfs_remove_fsid() if btrfs_sysfs_add_fsid() returns an error or
by adding a call to kobject_put() directly in btrfs_sysfs_add_fsid().
Here we choose the second option because it prevents the slightly
unusual error path handling requirements of kobject from leaking out
into btrfs functions.

Add a call to kobject_put() in the error path of kobject_add_and_init().
This causes the release method to be called if kobject_init_and_add()
fails.  open_tree() is the function that calls btrfs_sysfs_add_fsid()
and the error code in this function is already written with the
assumption that the release method is called during the error path of
open_tree() (as seen by the call to btrfs_sysfs_remove_fsid() under the
fail_fsdev_sysfs label).

Cc: stable@vger.kernel.org # v4.4+
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Tobin C. Harding 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman