This reverts commit 0dba1314. It causes
leaking of device numbers for SCSI when SCSI registers multiple gendisks
for one request_queue in succession. It can be easily reproduced using
Omar's script [1] on kernel with CONFIG_DEBUG_TEST_DRIVER_REMOVE.
Furthermore the protection provided by this commit is not needed anymore
as the problem it was fixing got also fixed by commit 165a5e22
"block: Move bdi_unregister() to del_gendisk()".

[1]: http://marc.info/?l=linux-block&m=148554717109098&w=2Signed-off-by: NJan Kara <jack@suse.cz>
Acked-by: NDan Williams <dan.j.williams@intel.com>
Tested-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Commit 165a5e22 "block: Move bdi_unregister() to del_gendisk()"
added disk->queue dereference to del_gendisk(). Although del_gendisk()
is not supposed to be called without disk->queue valid and
blk_unregister_queue() warns in that case, this change will make it oops
instead. Return to the old more robust behavior of just warning when
del_gendisk() gets called for gendisk with disk->queue being NULL.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Tested-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

bdi_writeback_congested structures get created for each blkcg and bdi
regardless whether bdi is registered or not. When they are created in
unregistered bdi and the request queue (and thus bdi) is then destroyed
while blkg still holds reference to bdi_writeback_congested structure,
this structure will be referencing freed bdi and last wb_congested_put()
will try to remove the structure from already freed bdi.

With commit 165a5e22 "block: Move bdi_unregister() to
del_gendisk()", SCSI started to destroy bdis without calling
bdi_unregister() first (previously it was calling bdi_unregister() even
for unregistered bdis) and thus the code detaching
bdi_writeback_congested in cgwb_bdi_destroy() was not triggered and we
started hitting this use-after-free bug. It is enough to boot a KVM
instance with virtio-scsi device to trigger this behavior.

Fix the problem by detaching bdi_writeback_congested structures in
bdi_exit() instead of bdi_unregister(). This is also more logical as
they can get attached to bdi regardless whether it ever got registered
or not.

Fixes: 165a5e22Signed-off-by: NJan Kara <jack@suse.cz>
Tested-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

SCSI can call device_add_disk() several times for one request queue when
a device in unbound and bound, creating new gendisk each time. This will
lead to bdi being repeatedly registered and unregistered. This was not a
big problem until commit 165a5e22 "block: Move bdi_unregister() to
del_gendisk()" since bdi was only registered repeatedly (bdi_register()
handles repeated calls fine, only we ended up leaking reference to
gendisk due to overwriting bdi->owner) but unregistered only in
blk_cleanup_queue() which didn't get called repeatedly. After
165a5e22 we were doing correct bdi_register() - bdi_unregister()
cycles however bdi_unregister() is not prepared for it. So make sure
bdi_unregister() cleans up bdi in such a way that it is prepared for
a possible following bdi_register() call.

An easy way to provoke this behavior is to enable
CONFIG_DEBUG_TEST_DRIVER_REMOVE and use scsi_debug driver to create a
scsi disk which immediately hangs without this fix.

Fixes: 165a5e22Signed-off-by: NJan Kara <jack@suse.cz>
Tested-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Fixes check that the opal user is within the range, and cleans up unused
method variables.
Signed-off-by: NJon Derrick <jonathan.derrick@intel.com>
Reviewed-by: NScott Bauer <scott.bauer@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

zram can handle at most SECTORS_PER_PAGE sectors in a bio's bvec. When using
the NVMe over Fabrics loopback target which potentially sends a huge bulk of
pages attached to the bio's bvec this results in a kernel panic because of
array out of bounds accesses in zram_decompress_page().
Signed-off-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

It is obviously that hctx->cpumask is per hctx, and both
share same lifetime, so this patch moves freeing of hctx->cpumask
into release handler of hctx's kobject.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Tested-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

This patch removes kobject_put() over hctx in __blk_mq_unregister_dev(),
and trys to keep lifetime consistent between hctx and hctx's kobject.

Now blk_mq_sysfs_register() and blk_mq_sysfs_unregister() become
totally symmetrical, and kobject's refcounter drops to zero just
when the hctx is freed.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Tested-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

Currently from kobject view, both q->mq_kobj and ctx->kobj can
be released during one cycle of blk_mq_register_dev() and
blk_mq_unregister_dev(). Actually, sw queue's lifetime is
same with its request queue's, which is covered by request_queue->kobj.

So we don't need to call kobject_put() for the two kinds of
kobject in __blk_mq_unregister_dev(), instead we do that
in release handler of request queue.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Tested-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

Both q->mq_kobj and sw queues' kobjects should have been initialized
once, instead of doing that each add_disk context.

Also this patch removes clearing of ctx in blk_mq_init_cpu_queues()
because percpu allocator fills zero to allocated variable.

This patch fixes one issue[1] reported from Omar.

[1] kernel wearning when doing unbind/bind on one scsi-mq device

[   19.347924] kobject (ffff8800791ea0b8): tried to init an initialized object, something is seriously wrong.
[   19.349781] CPU: 1 PID: 84 Comm: kworker/u8:1 Not tainted 4.10.0-rc7-00210-g53f39eeaa263 #34
[   19.350686] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-20161122_114906-anatol 04/01/2014
[   19.350920] Workqueue: events_unbound async_run_entry_fn
[   19.350920] Call Trace:
[   19.350920]  dump_stack+0x63/0x83
[   19.350920]  kobject_init+0x77/0x90
[   19.350920]  blk_mq_register_dev+0x40/0x130
[   19.350920]  blk_register_queue+0xb6/0x190
[   19.350920]  device_add_disk+0x1ec/0x4b0
[   19.350920]  sd_probe_async+0x10d/0x1c0 [sd_mod]
[   19.350920]  async_run_entry_fn+0x48/0x150
[   19.350920]  process_one_work+0x1d0/0x480
[   19.350920]  worker_thread+0x48/0x4e0
[   19.350920]  kthread+0x101/0x140
[   19.350920]  ? process_one_work+0x480/0x480
[   19.350920]  ? kthread_create_on_node+0x60/0x60
[   19.350920]  ret_from_fork+0x2c/0x40

Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Tested-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

Pull x86 fixes from Ingo Molnar:
 "Misc fixes and minor updates all over the place:

   - an SGI/UV fix
   - a defconfig update
   - a build warning fix
   - move the boot_params file to the arch location in debugfs
   - a pkeys fix
   - selftests fix
   - boot message fixes
   - sparse fixes
   - a resume warning fix
   - ioapic hotplug fixes
   - reboot quirks

  ... plus various minor cleanups"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/build/x86_64_defconfig: Enable CONFIG_R8169
  x86/reboot/quirks: Add ASUS EeeBook X205TA/W reboot quirk
  x86/hpet: Prevent might sleep splat on resume
  x86/boot: Correct setup_header.start_sys name
  x86/purgatory: Fix sparse warning, symbol not declared
  x86/purgatory: Make functions and variables static
  x86/events: Remove last remnants of old filenames
  x86/pkeys: Check against max pkey to avoid overflows
  x86/ioapic: Split IOAPIC hot-removal into two steps
  x86/PCI: Implement pcibios_release_device to release IRQ from IOAPIC
  x86/intel_rdt: Remove duplicate inclusion of linux/cpu.h
  x86/vmware: Remove duplicate inclusion of asm/timer.h
  x86/hyperv: Hide unused label
  x86/reboot/quirks: Add ASUS EeeBook X205TA reboot quirk
  x86/platform/uv/BAU: Fix HUB errors by remove initial write to sw-ack register
  x86/selftests: Add clobbers for int80 on x86_64
  x86/apic: Simplify enable_IR_x2apic(), remove try_to_enable_IR()
  x86/apic: Fix a warning message in logical CPU IDs allocation
  x86/kdebugfs: Move boot params hierarchy under (debugfs)/x86/

Pull timer fixes from Ingo Molnar:
 "This includes a fix for lockups caused by incorrect nsecs related
  cleanup, and a capabilities check fix for timerfd"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  jiffies: Revert bogus conversion of NSEC_PER_SEC to TICK_NSEC
  timerfd: Only check CAP_WAKE_ALARM when it is needed

Pull scheduler fixes from Ingo Molnar:
 "A fix for KVM's scheduler clock which (erroneously) was always marked
  unstable, a fix for RT/DL load balancing, plus latency fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface
  sched/core: Fix pick_next_task() for RT,DL
  sched/fair: Make select_idle_cpu() more aggressive

Pull perf fixes from Ingo Molnar:
 "This includes a fix for a crash if certain special addresses are
  kprobed, plus does a rename of two Kconfig variables that were a minor
  misnomer"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Rename CONFIG_[UK]PROBE_EVENT to CONFIG_[UK]PROBE_EVENTS
  kprobes/x86: Fix kernel panic when certain exception-handling addresses are probed

Pull locking fixes from Ingo Molnar:

 - Change the new refcount_t warnings from WARN() to WARN_ONCE()

 - two ww_mutex fixes

 - plus a new lockdep self-consistency check for a bug that triggered in
   practice

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/ww_mutex: Adjust the lock number for stress test
  locking/lockdep: Add nest_lock integrity test
  locking/ww_mutex: Replace cpu_relax() with cond_resched() for tests
  locking/refcounts: Change WARN() to WARN_ONCE()

Pull IRQ fix from Ingo Molnar:
 "Fix an ARM TI DRA7XX SoC irqchip driver local variables type
  bug/warning"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/crossbar: Fix incorrect type of local variables

Pull EFI fixes from Ingo Molnar:
 "A boot crash fix, and a secure boot related boot messages fix"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/arm: Fix boot crash with CONFIG_CPUMASK_OFFSTACK=y
  efi/libstub: Treat missing SecureBoot variable as Secure Boot disabled

Pull core fixes from Ingo Molnar:
 "A couple of sched.h splitup related build fixes, plus an objtool fix"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix another GCC jump table detection issue
  drivers/char/nwbutton: Fix build breakage caused by include file reshuffling
  h8300: Fix build breakage caused by header file changes
  avr32: Fix build error caused by include file reshuffling

Pull idr fix (and new tests) from Matthew Wilcox:
 "One urgent patch in here; freeing the correct IDA bitmap.

  Everything else is changes to the test suite"

* 'idr-4.11' of git://git.infradead.org/users/willy/linux-dax:
  radix tree test suite: Specify -m32 in LDFLAGS too
  ida: Free correct IDA bitmap
  radix tree test suite: Depend on Makefile and quieten grep
  radix tree test suite: Fix build with --as-needed
  radix tree test suite: Build 32 bit binaries
  radix tree test suite: Add performance test for radix_tree_join()
  radix tree test suite: Add performance test for radix_tree_split()
  radix tree test suite: Add performance benchmarks
  radix tree test suite: Add test for radix_tree_clear_tags()
  radix tree test suite: Add tests for ida_simple_get() and ida_simple_remove()
  radix tree test suite: Add test for idr_get_next()

Pull powerpc fixes from Michael Ellerman:
 "Five fairly small fixes for things that went in this cycle.

  A fairly large patch to rework the CAS logic on Power9, necessitated
  by a late change to the firmware API, and we can't boot without it.

  Three fixes going to stable, allowing more instructions to be emulated
  on LE, fixing a boot crash on 32-bit Freescale BookE machines, and the
  OPAL XICS workaround.

  And a patch from me to sort the selects under CONFIG PPC. Annoying
  churn, but worth it in the long run, and best for it to go in now to
  avoid conflicts.

  Thanks to:
    Alexey Kardashevskiy, Anton Blanchard, Balbir Singh, Gautham R.
    Shenoy, Laurentiu Tudor, Nicholas Piggin, Paul Mackerras, Ravi
    Bangoria, Sachin Sant, Shile Zhang, Suraj Jitindar Singh"

* tag 'powerpc-4.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Sort the selects under CONFIG_PPC
  powerpc/64: Fix L1D cache shape vector reporting L1I values
  powerpc/64: Avoid panic during boot due to divide by zero in init_cache_info()
  powerpc: Update to new option-vector-5 format for CAS
  powerpc: Parse the command line before calling CAS
  powerpc/xics: Work around limitations of OPAL XICS priority handling
  powerpc/64: Fix checksum folding in csum_add()
  powerpc/powernv: Fix opal tracepoints with JUMP_LABEL=n
  powerpc/booke: Fix boot crash due to null hugepd
  powerpc: Fix compiling a BE kernel with a powerpc64le toolchain
  selftest/powerpc: Fix false failures for skipped tests
  powerpc/powernv: Fix bug due to labeling ambiguity in power_enter_stop
  powerpc/64: Invalidate process table caching after setting process table
  powerpc: emulate_step() tests for load/store instructions
  powerpc: Emulation support for load/store instructions on LE

Merge branch 'stable/for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb

Pull swiotlb updates from Konrad Rzeszutek Wilk:
 "Two tiny implementations of the DMA API for callback in ARM (for Xen)"

* 'stable/for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb:
  swiotlb-xen: implement xen_swiotlb_get_sgtable callback
  swiotlb-xen: implement xen_swiotlb_dma_mmap callback

Michael's patch to use the default make rule for linking and the patch
from Rehas to use -m32 if building a 32-bit test-suite on a 64-bit
platform don't work well together.
Reported-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

There's a relatively rare race where we look at the per-cpu preallocated
IDA bitmap, see it's NULL, allocate a new one, and atomically update it.
If the kmalloc() happened to sleep and we were rescheduled to a different
CPU, or an interrupt came in at the exact right time, another task
might have successfully allocated a bitmap and already deposited it.
I forgot what the semantics of cmpxchg() were and ended up freeing the
wrong bitmap leading to KASAN reporting a use-after-free.

Dmitry found the bug with syzkaller & wrote the patch.  I wrote the test
case that will reproduce the bug without his patch being applied.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Changing the CFLAGS in the Makefile didn't always lead to a
recompilation because the OFILES didn't depend on the Makefile.
Also, after doing make clean, grep would still complain about
a missing map-shift.h; we need -s as well as -q.
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Currently the radix tree test suite doesn't build with toolchains that
use --as-needed by default, for example Ubuntu's:

  cc -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE -fsanitize=address -lpthread -lurcu main.o ... -o main
  /usr/bin/ld: regression1.o: undefined reference to symbol 'pthread_join@@GLIBC_2.17'
  /lib/powerpc64le-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line
  collect2: error: ld returned 1 exit status

This is caused by the custom makefile rules placing LDFLAGS before the
.o files that need the libraries.

We could fix it by using --no-as-needed, or rewriting the custom rules.
But we can also just drop the custom rules and move the libraries to
LDLIBS, and then the default rules work correctly - with the one caveat
that we need to add -fsanitize=address to LDFLAGS because that must be
passed to the linker as well as the compiler.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Add option 'make BUILD=32' for building 32-bit binaries.
Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Add performance benchmarks for radix tree insertion, tagging and deletion.
Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Assert that radix_tree_clear_tags() clears the tags on the passed node and
slot. Assert that the case where the radix tree has only one entry at index
zero and the node is NULL, is also handled.
Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Assert that ida_simple_get() allocates an id in the passed range or returns
error on failure, and ida_simple_remove() releases an allocated id.
Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Assert that idr_get_next() returns the next populated entry in the tree with
an ID greater than or equal to the value pointed to by @nextid argument.
Signed-off-by: NRehas Sachdeva <aquannie@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>

Pull namespace fix from Eric Biederman:
 "This fixes a race between put_ucounts and get_ucounts that can cause a
  use after free. The fix works by simplifying the code and so there is
  not even a temptation to be clever and play spinlock vs atomic
  reference games"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  ucount: Remove the atomicity from ucount->count

Pull tracing fixes from Steven Rostedt:
 "There was some breakage with the changes for jump labels in the 4.11
  merge window:

   - powerpc broke as jump labels uses the two LSB bits as flags in
     initialization.

     A check was added to make sure that all jump label entries were 4
     bytes aligned, but powerpc didn't work that way for modules. Adding
     an alignment in the module linker script appeared to be the best
     solution.

   - Jump labels also added an anonymous union to access those LSB bits
     as a normal long. But because this structure had static
     initialization, it broke older compilers that could not statically
     initialize anonymous unions without brackets.

   - The command line parameter for setting function graph filter broke
     the "EMPTY_HASH" descriptor by modifying it instead of creating a
     new hash to hold the entries.

   - The command line parameter ftrace_graph_max_depth was added to
     allow its setting at boot time. It uses existing code and only the
     command line hook was added.

     This is not really a fix, but as it uses existing code without
     affecting anything else, I added it to this release. It was ready
     before the merge window closed, but I wanted to let it sit in
     linux-next for a couple of days first"

* tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/graph: Add ftrace_graph_max_depth kernel parameter
  tracing: Add #undef to fix compile error
  jump_label: Add comment about initialization order for anonymous unions
  jump_label: Fix anonymous union initialization
  module: set __jump_table alignment to 8
  ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter
  tracing: Fix code comment for ftrace_ops_get_func()

commit 93825f2e converted NSEC_PER_SEC to TICK_NSEC because the author
confused NSEC_PER_JIFFY with NSEC_PER_SEC.

As a result, the calculation of refined jiffies got broken, triggering
lockups.

Fixes: 93825f2e ("jiffies: Reuse TICK_NSEC instead of NSEC_PER_JIFFY")
Reported-and-tested-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1488880534-3777-1-git-send-email-fweisbec@gmail.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Arnd Bergmann reported a (false positive) objtool warning:

  drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0xfe: sibling call from callable instruction with changed frame pointer

The issue is in find_switch_table().  It tries to find a switch
statement's jump table by walking backwards from an indirect jump
instruction, looking for a relocation to the .rodata section.  In this
case it stopped walking prematurely: the first .rodata relocation it
encountered was for a variable (resp_state_name) instead of a jump
table, so it just assumed there wasn't a jump table.

The fix is to ignore any .rodata relocation which refers to an ELF
object symbol.  This works because the jump tables are anonymous and
have no symbols associated with them.
Reported-by: NArnd Bergmann <arnd@arndb.de>
Tested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 3732710f ("objtool: Improve rare switch jump table pattern detection")
Link: http://lkml.kernel.org/r/20170302225723.3ndbsnl4hkqbne7a@trebleSigned-off-by: NIngo Molnar <mingo@kernel.org>

Fix:

  drivers/char/nwbutton.c: In function 'button_sequence_finished':
  drivers/char/nwbutton.c:134:3: error: implicit declaration of function 'kill_cad_pid'

The declaration has been moved from one include file to another.
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c3edc401 ("sched/headers: Move task_struct::signal and ...")
Link: http://lkml.kernel.org/r/1488762811-9022-1-git-send-email-linux@roeck-us.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Fix the following h8300 build failures:

  arch/h8300/kernel/ptrace_h.c: In function ‘trace_trap’:
  arch/h8300/kernel/ptrace_h.c:253:3: error: implicit declaration of function ‘force_sig’
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Fixes: c3edc401 ("sched/headers: Move task_struct::signal and ...")
Link: http://lkml.kernel.org/r/1488738434-3504-1-git-send-email-linux@roeck-us.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Various avr32 builds fail:

  arch/avr32/oprofile/backtrace.c:58: error: dereferencing pointer to incomplete type
  arch/avr32/oprofile/backtrace.c:60: error: implicit declaration of function 'user_mode'
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Acked-by: NHans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: oprofile-list@lists.sf.net
Fixes: f780d89a ("sched/headers: Remove <asm/ptrace.h> from ...")
Link: http://lkml.kernel.org/r/1488762357-4500-1-git-send-email-linux@roeck-us.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Always increment/decrement ucount->count under the ucounts_lock.  The
increments are there already and moving the decrements there means the
locking logic of the code is simpler.  This simplification in the
locking logic fixes a race between put_ucounts and get_ucounts that
could result in a use-after-free because the count could go zero then
be found by get_ucounts and then be freed by put_ucounts.

A bug presumably this one was found by a combination of syzkaller and
KASAN.  JongWhan Kim reported the syzkaller failure and Dmitry Vyukov
spotted the race in the code.

Cc: stable@vger.kernel.org
Fixes: f6b2db1a ("userns: Make the count of user namespaces per user")
Reported-by: NJongHwan Kim <zzoru007@gmail.com>
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Reviewed-by: NAndrei Vagin <avagin@gmail.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>