19 Sep, 2015

1 commit

  • Pull KVM fixes from Paolo Bonzini:
    "Mostly stable material, a lot of ARM fixes"

    * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits)
    sched: access local runqueue directly in single_task_running
    arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS'
    arm64: KVM: Remove all traces of the ThumbEE registers
    arm: KVM: Disable virtual timer even if the guest is not using it
    arm64: KVM: Disable virtual timer even if the guest is not using it
    arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resources
    KVM: s390: Replace incorrect atomic_or with atomic_andnot
    arm: KVM: Fix incorrect device to IPA mapping
    arm64: KVM: Fix user access for debug registers
    KVM: vmx: fix VPID is 0000H in non-root operation
    KVM: add halt_attempted_poll to VCPU stats
    kvm: fix zero length mmio searching
    kvm: fix double free for fast mmio eventfd
    kvm: factor out core eventfd assign/deassign logic
    kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd
    KVM: make the declaration of functions within 80 characters
    KVM: arm64: add workaround for Cortex-A57 erratum #852523
    KVM: fix polling for guest halt continued even if disable it
    arm/arm64: KVM: Fix PSCI affinity info return value for non valid cores
    arm64: KVM: set {v,}TCR_EL2 RES1 bits
    ...

    Linus Torvalds
     

18 Sep, 2015

4 commits

  • Pull irq updates from Thomas Gleixner:
    "This is a rather large update post rc1 due to the final steps of
    cleanups and API changes which had to wait for the preparatory patches
    to hit your tree.

    - Regression fixes for ARM GIC irqchips

    - Regression fixes and lockdep anotations for renesas irq chips

    - The leftovers of the cleanup and preparatory patches which have
    been ignored by maintainers

    - Final conversions of the newly merged users of obsolete APIs

    - Final removal of obsolete APIs

    - Final removal of ARM artifacts which had been introduced during the
    conversion of ARM to the generic interrupt code.

    - Final split of the irq_data into chip specific and common data to
    reflect the needs of hierarchical irq domains.

    - Treewide removal of the first argument of interrupt flow handlers,
    i.e. the irq number, which is not used by the majority of handlers
    and simple to retrieve from the other argument the irq descriptor.

    - A few comment updates and build warning fixes"

    * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
    arm64: Remove ununsed set_irq_flags
    ARM: Remove ununsed set_irq_flags
    sh: Kill off set_irq_flags usage
    irqchip: Kill off set_irq_flags usage
    gpu/drm: Kill off set_irq_flags usage
    genirq: Remove irq argument from irq flow handlers
    genirq: Move field 'msi_desc' from irq_data into irq_common_data
    genirq: Move field 'affinity' from irq_data into irq_common_data
    genirq: Move field 'handler_data' from irq_data into irq_common_data
    genirq: Move field 'node' from irq_data into irq_common_data
    irqchip/gic-v3: Use IRQD_FORWARDED_TO_VCPU flag
    irqchip/gic: Use IRQD_FORWARDED_TO_VCPU flag
    genirq: Provide IRQD_FORWARDED_TO_VCPU status flag
    genirq: Simplify irq_data_to_desc()
    genirq: Remove __irq_set_handler_locked()
    pinctrl/pistachio: Use irq_set_handler_locked
    gpio: vf610: Use irq_set_handler_locked
    powerpc/mpc8xx: Use irq_set_handler_locked()
    powerpc/ipic: Use irq_set_handler_locked()
    powerpc/cpm2: Use irq_set_handler_locked()
    ...

    Linus Torvalds
     
  • Commit 2ee507c47293 ("sched: Add function single_task_running to let a task
    check if it is the only task running on a cpu") referenced the current
    runqueue with the smp_processor_id. When CONFIG_DEBUG_PREEMPT is enabled,
    that is only allowed if preemption is disabled or the currrent task is
    bound to the local cpu (e.g. kernel worker).

    With commit f78195129963 ("kvm: add halt_poll_ns module parameter") KVM
    calls single_task_running. If CONFIG_DEBUG_PREEMPT is enabled that
    generates a lot of kernel messages.

    To avoid adding preemption in that cases, as it would limit the usefulness,
    we change single_task_running to access directly the cpu local runqueue.

    Cc: Tim Chen
    Suggested-by: Peter Zijlstra
    Acked-by: Peter Zijlstra (Intel)
    Cc:
    Fixes: 2ee507c472939db4b146d545352b8a7c79ef47f8
    Signed-off-by: Dominik Dingel
    Signed-off-by: Paolo Bonzini

    Dominik Dingel
     
  • Pull timer fixes from Ingo Molnar:
    "A fix for an abs()/abs64() bug that caused too slow NTP convergence on
    32-bit kernels, plus a removal of an obsolete clockevents driver
    facility after all users got converted during the merge window"

    * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
    clockevents: Remove unused set_mode() callback
    time: Fix timekeeping_freqadjust()'s incorrect use of abs() instead of abs64()

    Linus Torvalds
     
  • Pull scheduler fixes from Ingo Molnar:
    "A migrate_tasks() locking fix, and a late-coming nohz change plus a
    nohz debug check"

    * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
    sched: 'Annotate' migrate_tasks()
    nohz: Assert existing housekeepers when nohz full enabled
    nohz: Affine unpinned timers to housekeepers

    Linus Torvalds
     

17 Sep, 2015

1 commit


16 Sep, 2015

5 commits

  • Most interrupt flow handlers do not use the irq argument. Those few
    which use it can retrieve the irq number from the irq descriptor.

    Remove the argument.

    Search and replace was done with coccinelle and some extra helper
    scripts around it. Thanks to Julia for her help!

    Signed-off-by: Thomas Gleixner
    Cc: Julia Lawall
    Cc: Jiang Liu

    Thomas Gleixner
     
  • MSI descriptors are per-irq instead of per irqchip, so move it into
    struct irq_common_data.

    Signed-off-by: Jiang Liu
    Cc: Konrad Rzeszutek Wilk
    Cc: Tony Luck
    Cc: Bjorn Helgaas
    Cc: Benjamin Herrenschmidt
    Cc: Randy Dunlap
    Cc: Yinghai Lu
    Cc: Borislav Petkov
    Cc: Jason Cooper
    Cc: Kevin Cernekee
    Cc: Arnd Bergmann
    Cc: Marc Zyngier
    Link: http://lkml.kernel.org/r/1433145945-789-35-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner

    Jiang Liu
     
  • Irq affinity mask is per-irq instead of per irqchip, so move it into
    struct irq_common_data.

    Signed-off-by: Jiang Liu
    Cc: Konrad Rzeszutek Wilk
    Cc: Tony Luck
    Cc: Bjorn Helgaas
    Cc: Benjamin Herrenschmidt
    Cc: Randy Dunlap
    Cc: Yinghai Lu
    Cc: Borislav Petkov
    Cc: Jason Cooper
    Cc: Kevin Cernekee
    Cc: Arnd Bergmann
    Link: http://lkml.kernel.org/r/1433303281-27688-1-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner

    Jiang Liu
     
  • Handler data (handler_data) is per-irq instead of per irqchip, so move
    it into struct irq_common_data.

    Signed-off-by: Jiang Liu
    Cc: Konrad Rzeszutek Wilk
    Cc: Tony Luck
    Cc: Bjorn Helgaas
    Cc: Benjamin Herrenschmidt
    Cc: Randy Dunlap
    Cc: Yinghai Lu
    Cc: Borislav Petkov
    Cc: Jason Cooper
    Cc: Kevin Cernekee
    Cc: Arnd Bergmann
    Cc: Marc Zyngier
    Link: http://lkml.kernel.org/r/1433145945-789-13-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner

    Jiang Liu
     
  • NUMA node information is per-irq instead of per-irqchip, so move it into
    struct irq_common_data. Also use CONFIG_NUMA to guard irq_common_data.node.

    Signed-off-by: Jiang Liu
    Cc: Konrad Rzeszutek Wilk
    Cc: Tony Luck
    Cc: Bjorn Helgaas
    Cc: Benjamin Herrenschmidt
    Cc: Randy Dunlap
    Cc: Yinghai Lu
    Cc: Borislav Petkov
    Cc: Jason Cooper
    Cc: Kevin Cernekee
    Cc: Arnd Bergmann
    Link: http://lkml.kernel.org/r/1433145945-789-8-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner

    Jiang Liu
     

14 Sep, 2015

1 commit

  • All users are migrated to the per-state callbacks, get rid of the
    unused interface and the core support code.

    Signed-off-by: Viresh Kumar
    Signed-off-by: Thomas Gleixner
    Cc: linaro-kernel@lists.linaro.org
    Cc: John Stultz
    Cc: Peter Zijlstra
    Link: http://lkml.kernel.org/r/fd60de14cf6d125489c031207567bb255ad946f6.1441943991.git.viresh.kumar@linaro.org
    Signed-off-by: Ingo Molnar

    Viresh Kumar
     

13 Sep, 2015

1 commit

  • The internal clocksteering done for fine-grained error
    correction uses a logarithmic approximation, so any time
    adjtimex() adjusts the clock steering, timekeeping_freqadjust()
    quickly approximates the correct clock frequency over a series
    of ticks.

    Unfortunately, the logic in timekeeping_freqadjust(), introduced
    in commit:

    dc491596f639 ("timekeeping: Rework frequency adjustments to work better w/ nohz")

    used the abs() function with a s64 error value to calculate the
    size of the approximated adjustment to be made.

    Per include/linux/kernel.h:

    "abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()".

    Thus on 32-bit platforms, this resulted in the clocksteering to
    take a quite dampended random walk trying to converge on the
    proper frequency, which caused the adjustments to be made much
    slower then intended (most easily observed when large
    adjustments are made).

    This patch fixes the issue by using abs64() instead.

    Reported-by: Nuno Gonçalves
    Tested-by: Nuno Goncalves
    Signed-off-by: John Stultz
    Cc: # v3.17+
    Cc: Linus Torvalds
    Cc: Miroslav Lichvar
    Cc: Peter Zijlstra
    Cc: Prarit Bhargava
    Cc: Richard Cochran
    Cc: Thomas Gleixner
    Link: http://lkml.kernel.org/r/1441840051-20244-1-git-send-email-john.stultz@linaro.org
    Signed-off-by: Ingo Molnar

    John Stultz
     

12 Sep, 2015

3 commits

  • Merge fourth patch-bomb from Andrew Morton:

    - sys_membarier syscall

    - seq_file interface changes

    - a few misc fixups

    * emailed patches from Andrew Morton :
    revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each"
    mm/early_ioremap: add explicit #include of asm/early_ioremap.h
    fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
    selftests: enhance membarrier syscall test
    selftests: add membarrier syscall test
    sys_membarrier(): system-wide memory barrier (generic, x86)
    MODSIGN: fix a compilation warning in extract-cert

    Linus Torvalds
     
  • Pull more power management and ACPI updates from Rafael Wysocki:
    "These are mostly fixes and cleanups on top of the previous PM+ACPI
    pull request (cpufreq core and drivers, cpuidle, generic power domains
    framework). Some of them didn't make to that pull request and some
    fix issues introduced by it.

    The only really new thing is the support for suspend frequency in the
    cpufreq-dt driver, but it is needed to fix an issue with Exynos
    platforms.

    Specifics:

    - build fix for the new Mediatek MT8173 cpufreq driver (Guenter
    Roeck).

    - generic power domains framework fixes (power on error code path,
    subdomain removal) and cleanup of a deprecated API user (Geert
    Uytterhoeven, Jon Hunter, Ulf Hansson).

    - cpufreq-dt driver fixes including two fixes for bugs related to the
    new Operating Performance Points Device Tree bindings introduced
    recently (Viresh Kumar).

    - suspend frequency support for the cpufreq-dt driver (Bartlomiej
    Zolnierkiewicz, Viresh Kumar).

    - cpufreq core cleanups (Viresh Kumar).

    - intel_pstate driver fixes (Chen Yu, Kristen Carlson Accardi).

    - additional sanity check in the cpuidle core (Xunlei Pang).

    - fix for a comment related to CPU power management (Lina Iyer)"

    * tag 'pm+acpi-4.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
    intel_pstate: fix PCT_TO_HWP macro
    intel_pstate: Fix user input of min/max to legal policy region
    PM / OPP: Return suspend_opp only if it is enabled
    cpufreq-dt: add suspend frequency support
    cpufreq: allow cpufreq_generic_suspend() to work without suspend frequency
    PM / OPP: add dev_pm_opp_get_suspend_opp() helper
    staging: board: Migrate away from __pm_genpd_name_add_device()
    cpufreq: Use __func__ to print function's name
    cpufreq: staticize cpufreq_cpu_get_raw()
    PM / Domains: Ensure subdomain is not in use before removing
    cpufreq: Add ARM_MT8173_CPUFREQ dependency on THERMAL
    cpuidle/coupled: Add sanity check for safe_state_index
    PM / Domains: Try power off masters in error path of __pm_genpd_poweron()
    cpufreq: dt: Tolerance applies on both sides of target voltage
    cpufreq: dt: Print error on failing to mark OPPs as shared
    cpufreq: dt: Check OPP count before marking them shared
    kernel/cpu_pm: fix cpu_cluster_pm_exit comment

    Linus Torvalds
     
  • Here is an implementation of a new system call, sys_membarrier(), which
    executes a memory barrier on all threads running on the system. It is
    implemented by calling synchronize_sched(). It can be used to
    distribute the cost of user-space memory barriers asymmetrically by
    transforming pairs of memory barriers into pairs consisting of
    sys_membarrier() and a compiler barrier. For synchronization primitives
    that distinguish between read-side and write-side (e.g. userspace RCU
    [1], rwlocks), the read-side can be accelerated significantly by moving
    the bulk of the memory barrier overhead to the write-side.

    The existing applications of which I am aware that would be improved by
    this system call are as follows:

    * Through Userspace RCU library (http://urcu.so)
    - DNS server (Knot DNS) https://www.knot-dns.cz/
    - Network sniffer (http://netsniff-ng.org/)
    - Distributed object storage (https://sheepdog.github.io/sheepdog/)
    - User-space tracing (http://lttng.org)
    - Network storage system (https://www.gluster.org/)
    - Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
    - Financial software (https://lkml.org/lkml/2015/3/23/189)

    Those projects use RCU in userspace to increase read-side speed and
    scalability compared to locking. Especially in the case of RCU used by
    libraries, sys_membarrier can speed up the read-side by moving the bulk of
    the memory barrier cost to synchronize_rcu().

    * Direct users of sys_membarrier
    - core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)

    Microsoft core dotnet GC developers are planning to use the mprotect()
    side-effect of issuing memory barriers through IPIs as a way to implement
    Windows FlushProcessWriteBuffers() on Linux. They are referring to
    sys_membarrier in their github thread, specifically stating that
    sys_membarrier() is what they are looking for.

    To explain the benefit of this scheme, let's introduce two example threads:

    Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
    Thread B (frequent, e.g. executing liburcu
    rcu_read_lock()/rcu_read_unlock())

    In a scheme where all smp_mb() in thread A are ordering memory accesses
    with respect to smp_mb() present in Thread B, we can change each
    smp_mb() within Thread A into calls to sys_membarrier() and each
    smp_mb() within Thread B into compiler barriers "barrier()".

    Before the change, we had, for each smp_mb() pairs:

    Thread A Thread B
    previous mem accesses previous mem accesses
    smp_mb() smp_mb()
    following mem accesses following mem accesses

    After the change, these pairs become:

    Thread A Thread B
    prev mem accesses prev mem accesses
    sys_membarrier() barrier()
    follow mem accesses follow mem accesses

    As we can see, there are two possible scenarios: either Thread B memory
    accesses do not happen concurrently with Thread A accesses (1), or they
    do (2).

    1) Non-concurrent Thread A vs Thread B accesses:

    Thread A Thread B
    prev mem accesses
    sys_membarrier()
    follow mem accesses
    prev mem accesses
    barrier()
    follow mem accesses

    In this case, thread B accesses will be weakly ordered. This is OK,
    because at that point, thread A is not particularly interested in
    ordering them with respect to its own accesses.

    2) Concurrent Thread A vs Thread B accesses

    Thread A Thread B
    prev mem accesses prev mem accesses
    sys_membarrier() barrier()
    follow mem accesses follow mem accesses

    In this case, thread B accesses, which are ensured to be in program
    order thanks to the compiler barrier, will be "upgraded" to full
    smp_mb() by synchronize_sched().

    * Benchmarks

    On Intel Xeon E5405 (8 cores)
    (one thread is calling sys_membarrier, the other 7 threads are busy
    looping)

    1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.

    * User-space user of this system call: Userspace RCU library

    Both the signal-based and the sys_membarrier userspace RCU schemes
    permit us to remove the memory barrier from the userspace RCU
    rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
    accelerating them. These memory barriers are replaced by compiler
    barriers on the read-side, and all matching memory barriers on the
    write-side are turned into an invocation of a memory barrier on all
    active threads in the process. By letting the kernel perform this
    synchronization rather than dumbly sending a signal to every process
    threads (as we currently do), we diminish the number of unnecessary wake
    ups and only issue the memory barriers on active threads. Non-running
    threads do not need to execute such barrier anyway, because these are
    implied by the scheduler context switches.

    Results in liburcu:

    Operations in 10s, 6 readers, 2 writers:

    memory barriers in reader: 1701557485 reads, 2202847 writes
    signal-based scheme: 9830061167 reads, 6700 writes
    sys_membarrier: 9952759104 reads, 425 writes
    sys_membarrier (dyn. check): 7970328887 reads, 425 writes

    The dynamic sys_membarrier availability check adds some overhead to
    the read-side compared to the signal-based scheme, but besides that,
    sys_membarrier slightly outperforms the signal-based scheme. However,
    this non-expedited sys_membarrier implementation has a much slower grace
    period than signal and memory barrier schemes.

    Besides diminishing the number of wake-ups, one major advantage of the
    membarrier system call over the signal-based scheme is that it does not
    need to reserve a signal. This plays much more nicely with libraries,
    and with processes injected into for tracing purposes, for which we
    cannot expect that signals will be unused by the application.

    An expedited version of this system call can be added later on to speed
    up the grace period. Its implementation will likely depend on reading
    the cpu_curr()->mm without holding each CPU's rq lock.

    This patch adds the system call to x86 and to asm-generic.

    [1] http://urcu.so

    membarrier(2) man page:

    MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)

    NAME
    membarrier - issue memory barriers on a set of threads

    SYNOPSIS
    #include

    int membarrier(int cmd, int flags);

    DESCRIPTION
    The cmd argument is one of the following:

    MEMBARRIER_CMD_QUERY
    Query the set of supported commands. It returns a bitmask of
    supported commands.

    MEMBARRIER_CMD_SHARED
    Execute a memory barrier on all threads running on the system.
    Upon return from system call, the caller thread is ensured that
    all running threads have passed through a state where all memory
    accesses to user-space addresses match program order between
    entry to and return from the system call (non-running threads
    are de facto in such a state). This covers threads from all pro=E2=80=90
    cesses running on the system. This command returns 0.

    The flags argument needs to be 0. For future extensions.

    All memory accesses performed in program order from each targeted
    thread is guaranteed to be ordered with respect to sys_membarrier(). If
    we use the semantic "barrier()" to represent a compiler barrier forcing
    memory accesses to be performed in program order across the barrier,
    and smp_mb() to represent explicit memory barriers forcing full memory
    ordering across the barrier, we have the following ordering table for
    each pair of barrier(), sys_membarrier() and smp_mb():

    The pair ordering is detailed as (O: ordered, X: not ordered):

    barrier() smp_mb() sys_membarrier()
    barrier() X X O
    smp_mb() X O O
    sys_membarrier() O O O

    RETURN VALUE
    On success, these system calls return zero. On error, -1 is returned,
    and errno is set appropriately. For a given command, with flags
    argument set to 0, this system call is guaranteed to always return the
    same value until reboot.

    ERRORS
    ENOSYS System call is not implemented.

    EINVAL Invalid arguments.

    Linux 2015-04-15 MEMBARRIER(2)

    Signed-off-by: Mathieu Desnoyers
    Reviewed-by: Paul E. McKenney
    Reviewed-by: Josh Triplett
    Cc: KOSAKI Motohiro
    Cc: Steven Rostedt
    Cc: Nicholas Miell
    Cc: Ingo Molnar
    Cc: Alan Cox
    Cc: Lai Jiangshan
    Cc: Stephen Hemminger
    Cc: Thomas Gleixner
    Cc: Peter Zijlstra
    Cc: David Howells
    Cc: Pranith Kumar
    Cc: Michael Kerrisk
    Cc: Shuah Khan
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mathieu Desnoyers
     

11 Sep, 2015

19 commits

  • * pm-cpu:
    kernel/cpu_pm: fix cpu_cluster_pm_exit comment

    * pm-cpuidle:
    cpuidle/coupled: Add sanity check for safe_state_index

    * pm-domains:
    staging: board: Migrate away from __pm_genpd_name_add_device()
    PM / Domains: Ensure subdomain is not in use before removing
    PM / Domains: Try power off masters in error path of __pm_genpd_poweron()

    Rafael J. Wysocki
     
  • Kernel testing triggered this warning:

    | WARNING: CPU: 0 PID: 13 at kernel/sched/core.c:1156 do_set_cpus_allowed+0x7e/0x80()
    | Modules linked in:
    | CPU: 0 PID: 13 Comm: migration/0 Not tainted 4.2.0-rc1-00049-g25834c7 #2
    | Call Trace:
    | dump_stack+0x4b/0x75
    | warn_slowpath_common+0x8b/0xc0
    | warn_slowpath_null+0x22/0x30
    | do_set_cpus_allowed+0x7e/0x80
    | cpuset_cpus_allowed_fallback+0x7c/0x170
    | select_fallback_rq+0x221/0x280
    | migration_call+0xe3/0x250
    | notifier_call_chain+0x53/0x70
    | __raw_notifier_call_chain+0x1e/0x30
    | cpu_notify+0x28/0x50
    | take_cpu_down+0x22/0x40
    | multi_cpu_stop+0xd5/0x140
    | cpu_stopper_thread+0xbc/0x170
    | smpboot_thread_fn+0x174/0x2f0
    | kthread+0xc4/0xe0
    | ret_from_kernel_thread+0x21/0x30

    As Peterz pointed out:

    | So the normal rules for changing task_struct::cpus_allowed are holding
    | both pi_lock and rq->lock, such that holding either stabilizes the mask.
    |
    | This is so that wakeup can happen without rq->lock and load-balance
    | without pi_lock.
    |
    | From this we already get the relaxation that we can omit acquiring
    | rq->lock if the task is not on the rq, because in that case
    | load-balancing will not apply to it.
    |
    | ** these are the rules currently tested in do_set_cpus_allowed() **
    |
    | Now, since __set_cpus_allowed_ptr() uses task_rq_lock() which
    | unconditionally acquires both locks, we could get away with holding just
    | rq->lock when on_rq for modification because that'd still exclude
    | __set_cpus_allowed_ptr(), it would also work against
    | __kthread_bind_mask() because that assumes !on_rq.
    |
    | That said, this is all somewhat fragile.
    |
    | Now, I don't think dropping rq->lock is quite as disastrous as it
    | usually is because !cpu_active at this point, which means load-balance
    | will not interfere, but that too is somewhat fragile.
    |
    | So we end up with a choice of two fragile..

    This patch fixes it by following the rules for changing
    task_struct::cpus_allowed with both pi_lock and rq->lock held.

    Reported-by: kernel test robot
    Reported-by: Sasha Levin
    Signed-off-by: Wanpeng Li
    [ Modified changelog and patch. ]
    Signed-off-by: Peter Zijlstra (Intel)
    Cc: Linus Torvalds
    Cc: Peter Zijlstra
    Cc: Thomas Gleixner
    Link: http://lkml.kernel.org/r/BLU436-SMTP1660820490DE202E3934ED3806E0@phx.gbl
    Signed-off-by: Ingo Molnar

    Wanpeng Li
     
  • Dave ran into horrible performance on a VM without PARAVIRT_SPINLOCKS
    set and Linus noted that the test-and-set implementation was retarded.

    One should spin on the variable with a load, not a RMW.

    While there, remove 'queued' from the name, as the lock isn't queued
    at all, but a simple test-and-set.

    Suggested-by: Linus Torvalds
    Reported-by: Dave Chinner
    Tested-by: Dave Chinner
    Signed-off-by: Peter Zijlstra (Intel)
    Cc: Peter Zijlstra
    Cc: Thomas Gleixner
    Cc: Waiman Long
    Cc: stable@vger.kernel.org # v4.2+
    Link: http://lkml.kernel.org/r/20150904152523.GR18673@twins.programming.kicks-ass.net
    Signed-off-by: Ingo Molnar

    Peter Zijlstra
     
  • Merge third patch-bomb from Andrew Morton:

    - even more of the rest of MM

    - lib/ updates

    - checkpatch updates

    - small changes to a few scruffy filesystems

    - kmod fixes/cleanups

    - kexec updates

    - a dma-mapping cleanup series from hch

    * emailed patches from Andrew Morton : (81 commits)
    dma-mapping: consolidate dma_set_mask
    dma-mapping: consolidate dma_supported
    dma-mapping: cosolidate dma_mapping_error
    dma-mapping: consolidate dma_{alloc,free}_noncoherent
    dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}
    mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd()
    mm: make sure all file VMAs have ->vm_ops set
    mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
    mm: mark most vm_operations_struct const
    namei: fix warning while make xmldocs caused by namei.c
    ipc: convert invalid scenarios to use WARN_ON
    zlib_deflate/deftree: remove bi_reverse()
    lib/decompress_unlzma: Do a NULL check for pointer
    lib/decompressors: use real out buf size for gunzip with kernel
    fs/affs: make root lookup from blkdev logical size
    sysctl: fix int -> unsigned long assignments in INT_MIN case
    kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo
    kexec: align crash_notes allocation to make it be inside one physical page
    kexec: remove unnecessary test in kimage_alloc_crash_control_pages()
    kexec: split kexec_load syscall from kexec core code
    ...

    Linus Torvalds
     
  • Pull networking fixes from David Miller:

    1) Fix out-of-bounds array access in netfilter ipset, from Jozsef
    Kadlecsik.

    2) Use correct free operation on netfilter conntrack templates, from
    Daniel Borkmann.

    3) Fix route leak in SCTP, from Marcelo Ricardo Leitner.

    4) Fix sizeof(pointer) in mac80211, from Thierry Reding.

    5) Fix cache pointer comparison in ip6mr leading to missed unlock of
    mrt_lock. From Richard Laing.

    6) rds_conn_lookup() needs to consider network namespace in key
    comparison, from Sowmini Varadhan.

    7) Fix deadlock in TIPC code wrt broadcast link wakeups, from Kolmakov
    Dmitriy.

    8) Fix fd leaks in bpf syscall, from Daniel Borkmann.

    9) Fix error recovery when installing ipv6 multipath routes, we would
    delete the old route before we would know if we could fully commit
    to the new set of nexthops. Fix from Roopa Prabhu.

    10) Fix run-time suspend problems in r8152, from Hayes Wang.

    11) In fec, don't program the MAC address into the chip when the clocks
    are gated off. From Fugang Duan.

    12) Fix poll behavior for netlink sockets when using rx ring mmap, from
    Daniel Borkmann.

    13) Don't allocate memory with GFP_KERNEL from get_stats64 in r8169
    driver, from Corinna Vinschen.

    14) In TCP Cubic congestion control, handle idle periods better where we
    are application limited, in order to keep cwnd from growing out of
    control. From Eric Dumzet.

    * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (65 commits)
    tcp_cubic: better follow cubic curve after idle period
    tcp: generate CA_EVENT_TX_START on data frames
    xen-netfront: respect user provided max_queues
    xen-netback: respect user provided max_queues
    r8169: Fix sleeping function called during get_stats64, v2
    ether: add IEEE 1722 ethertype - TSN
    netlink, mmap: fix edge-case leakages in nf queue zero-copy
    netlink, mmap: don't walk rx ring on poll if receive queue non-empty
    cxgb4: changes for new firmware 1.14.4.0
    net: fec: add netif status check before set mac address
    r8152: fix the runtime suspend issues
    r8152: split DRIVER_VERSION
    ipv6: fix ifnullfree.cocci warnings
    add microchip LAN88xx phy driver
    stmmac: fix check for phydev being open
    net: qlcnic: delete redundant memsets
    net: mv643xx_eth: use kzalloc
    net: jme: use kzalloc() instead of kmalloc+memset
    net: cavium: liquidio: use kzalloc in setup_glist()
    net: ipv6: use common fib_default_rule_pref
    ...

    Linus Torvalds
     
  • The following

    if (val < 0)
    *lvalp = (unsigned long)-val;

    is incorrect because the compiler is free to assume -val to be positive
    and use a sign-extend instruction for extending the bit pattern. This is
    a problem if val == INT_MIN:

    # echo -2147483648 >/proc/sys/dev/scsi/logging_level
    # cat /proc/sys/dev/scsi/logging_level
    -18446744071562067968

    Cast to unsigned long before negation - that way we first sign-extend and
    then negate an unsigned, which is well defined. With this:

    # cat /proc/sys/dev/scsi/logging_level
    -2147483648

    Signed-off-by: Ilya Dryomov
    Cc: Mikulas Patocka
    Cc: Robert Xiao
    Cc: "Eric W. Biederman"
    Cc: Kees Cook
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ilya Dryomov
     
  • In x86_64, since v2.6.26 the KERNEL_IMAGE_SIZE is changed to 512M, and
    accordingly the MODULES_VADDR is changed to 0xffffffffa0000000. However,
    in v3.12 Kees Cook introduced kaslr to randomise the location of kernel.
    And the kernel text mapping addr space is enlarged from 512M to 1G. That
    means now KERNEL_IMAGE_SIZE is variable, its value is 512M when kaslr
    support is not compiled in and 1G when kaslr support is compiled in.
    Accordingly the MODULES_VADDR is changed too to be:

    #define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE)

    So when kaslr is compiled in and enabled, the kernel text mapping addr
    space and modules vaddr space need be adjusted. Otherwise makedumpfile
    will collapse since the addr for some symbols is not correct.

    Hence KERNEL_IMAGE_SIZE need be exported to vmcoreinfo and got in
    makedumpfile to help calculate MODULES_VADDR.

    Signed-off-by: Baoquan He
    Acked-by: Kees Cook
    Acked-by: Vivek Goyal
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Baoquan He
     
  • People reported that crash_notes in /proc/vmcore were corrupted and this
    cause crash kdump failure. With code debugging and log we got the root
    cause. This is because percpu variable crash_notes are allocated in 2
    vmalloc pages. Currently percpu is based on vmalloc by default. Vmalloc
    can't guarantee 2 continuous vmalloc pages are also on 2 continuous
    physical pages. So when 1st kernel exports the starting address and size
    of crash_notes through sysfs like below:

    /sys/devices/system/cpu/cpux/crash_notes
    /sys/devices/system/cpu/cpux/crash_notes_size

    kdump kernel use them to get the content of crash_notes. However the 2nd
    part may not be in the next neighbouring physical page as we expected if
    crash_notes are allocated accross 2 vmalloc pages. That's why
    nhdr_ptr->n_namesz or nhdr_ptr->n_descsz could be very huge in
    update_note_header_size_elf64() and cause note header merging failure or
    some warnings.

    In this patch change to call __alloc_percpu() to passed in the align value
    by rounding crash_notes_size up to the nearest power of two. This makes
    sure the crash_notes is allocated inside one physical page since
    sizeof(note_buf_t) in all ARCHS is smaller than PAGE_SIZE. Meanwhile add
    a BUILD_BUG_ON to break compile if size is bigger than PAGE_SIZE since
    crash_notes definitely will be in 2 pages. That need be avoided, and need
    be reported if it's unavoidable.

    [akpm@linux-foundation.org: use correct comment layout]
    Signed-off-by: Baoquan He
    Cc: Eric W. Biederman
    Cc: Vivek Goyal
    Cc: Dave Young
    Cc: Lisa Mitchell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Baoquan He
     
  • Transforming PFN(Page Frame Number) to struct page is never failure, so we
    can simplify the code logic to do the image->control_page assignment
    directly in the loop, and remove the unnecessary conditional judgement.

    Signed-off-by: Minfei Huang
    Acked-by: Dave Young
    Acked-by: Vivek Goyal
    Cc: Simon Horman
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Minfei Huang
     
  • There are two kexec load syscalls, kexec_load another and kexec_file_load.
    kexec_file_load has been splited as kernel/kexec_file.c. In this patch I
    split kexec_load syscall code to kernel/kexec.c.

    And add a new kconfig option KEXEC_CORE, so we can disable kexec_load and
    use kexec_file_load only, or vice verse.

    The original requirement is from Ted Ts'o, he want kexec kernel signature
    being checked with CONFIG_KEXEC_VERIFY_SIG enabled. But kexec-tools use
    kexec_load syscall can bypass the checking.

    Vivek Goyal proposed to create a common kconfig option so user can compile
    in only one syscall for loading kexec kernel. KEXEC/KEXEC_FILE selects
    KEXEC_CORE so that old config files still work.

    Because there's general code need CONFIG_KEXEC_CORE, so I updated all the
    architecture Kconfig with a new option KEXEC_CORE, and let KEXEC selects
    KEXEC_CORE in arch Kconfig. Also updated general kernel code with to
    kexec_load syscall.

    [akpm@linux-foundation.org: coding-style fixes]
    Signed-off-by: Dave Young
    Cc: Eric W. Biederman
    Cc: Vivek Goyal
    Cc: Petr Tesarik
    Cc: Theodore Ts'o
    Cc: Josh Boyer
    Cc: David Howells
    Cc: Geert Uytterhoeven
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Dave Young
     
  • Split kexec_file syscall related code to another file kernel/kexec_file.c
    so that the #ifdef CONFIG_KEXEC_FILE in kexec.c can be dropped.

    Sharing variables and functions are moved to kernel/kexec_internal.h per
    suggestion from Vivek and Petr.

    [akpm@linux-foundation.org: fix bisectability]
    [akpm@linux-foundation.org: declare the various arch_kexec functions]
    [akpm@linux-foundation.org: fix build]
    Signed-off-by: Dave Young
    Cc: Eric W. Biederman
    Cc: Vivek Goyal
    Cc: Petr Tesarik
    Cc: Theodore Ts'o
    Cc: Josh Boyer
    Cc: David Howells
    Cc: Geert Uytterhoeven
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Dave Young
     
  • The UMH_WAIT_PROC handler runs in its own thread in order to make sure
    that waiting for the exec kernel thread completion won't block other
    usermodehelper queued jobs.

    On older workqueue implementations, worklets couldn't sleep without
    blocking the rest of the queue. But now the workqueue subsystem handles
    that. Khelper still had the older limitation due to its singlethread
    properties but we replaced it to system unbound workqueues.

    Those are affine to the current node and can block up to some number of
    instances.

    They are a good candidate to handle UMH_WAIT_PROC assuming that we have
    enough system unbound workers to handle lots of parallel usermodehelper
    jobs.

    Signed-off-by: Frederic Weisbecker
    Cc: Rik van Riel
    Reviewed-by: Oleg Nesterov
    Cc: Christoph Lameter
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Frederic Weisbecker
     
  • We need to launch the usermodehelper kernel threads with the widest
    affinity and this is partly why we use khelper. This workqueue has
    unbound properties and thus a wide affinity inherited by all its children.

    Now khelper also has special properties that we aren't much interested in:
    ordered and singlethread. There is really no need about ordering as all
    we do is creating kernel threads. This can be done concurrently. And
    singlethread is a useless limitation as well.

    The workqueue engine already proposes generic unbound workqueues that
    don't share these useless properties and handle well parallel jobs.

    The only worrysome specific is their affinity to the node of the current
    CPU. It's fine for creating the usermodehelper kernel threads but those
    inherit this affinity for longer jobs such as requesting modules.

    This patch proposes to use these node affine unbound workqueues assuming
    that a node is sufficient to handle several parallel usermodehelper
    requests.

    Signed-off-by: Frederic Weisbecker
    Cc: Rik van Riel
    Reviewed-by: Oleg Nesterov
    Cc: Christoph Lameter
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Frederic Weisbecker
     
  • There seem to be quite some confusions on the comments, likely due to
    changes that came after them.

    Now since it's very non obvious why we have 3 levels of asynchronous code
    to implement usermodehelpers, it's important to comment in detail the
    reason of this layout.

    Signed-off-by: Frederic Weisbecker
    Cc: Rik van Riel
    Reviewed-by: Oleg Nesterov
    Cc: Christoph Lameter
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Frederic Weisbecker
     
  • Khelper is affine to all CPUs. Now since it creates the
    call_usermodehelper_exec_[a]sync() kernel threads, those inherit the wide
    affinity.

    As such explicitly forcing a wide affinity from those kernel threads
    is like a no-op.

    Just remove it. It's needless and it breaks CPU isolation users who
    rely on workqueue affinity tuning.

    Signed-off-by: Frederic Weisbecker
    Cc: Rik van Riel
    Reviewed-by: Oleg Nesterov
    Cc: Christoph Lameter
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Frederic Weisbecker
     
  • This patchset does a bunch of cleanups and converts khelper to use system
    unbound workqueues. The 3 first patches should be uncontroversial. The
    last 2 patches are debatable.

    Kmod creates kernel threads that perform userspace jobs and we want those
    to have a large affinity in order not to contend busy CPUs. This is
    (partly) why we use khelper which has a wide affinity that the kernel
    threads it create can inherit from. Now khelper is a dedicated workqueue
    that has singlethread properties which we aren't interested in.

    Hence those two debatable changes:

    _ We would like to use generic workqueues. System unbound workqueues are
    a very good candidate but they are not wide affine, only node affine.
    Now probably a node is enough to perform many parallel kmod jobs.

    _ We would like to remove the wait_for_helper kernel thread (UMH_WAIT_PROC
    handler) to use the workqueue. It means that if the workqueue blocks,
    and no other worker can take pending kmod request, we can be screwed.
    Now if we have 512 threads, this should be enough.

    This patch (of 5):

    Underscores on function names aren't much verbose to explain the purpose
    of a function. And kmod has interesting such flavours.

    Lets rename the following functions:

    * __call_usermodehelper -> call_usermodehelper_exec_work
    * ____call_usermodehelper -> call_usermodehelper_exec_async
    * wait_for_helper -> call_usermodehelper_exec_sync

    Signed-off-by: Frederic Weisbecker
    Cc: Rik van Riel
    Reviewed-by: Oleg Nesterov
    Cc: Christoph Lameter
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Frederic Weisbecker
     
  • If request_module() successfully runs modprobe, but modprobe exits with a
    non-zero status, then the return value from request_module() will be that
    (positive) error status. So the return from request_module can be:

    negative errno
    zero for success
    positive exit code.

    Signed-off-by: NeilBrown
    Cc: Goldwyn Rodrigues
    Cc: Oleg Nesterov
    Cc: Tejun Heo
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    NeilBrown
     
  • Commit e0e817392b9a ("CRED: Add some configurable debugging [try #6]")
    added the kdebug mechanism to this file back in 2009.

    The kdebug macro calls no_printk which always evaluates arguments.

    Most of the kdebug uses have an unnecessary call of
    atomic_read(&cred->usage)

    Make the kdebug macro do nothing by defining it with
    do { if (0) no_printk(...); } while (0)
    when not enabled.

    $ size kernel/cred.o* (defconfig x86-64)
    text data bss dec hex filename
    2748 336 8 3092 c14 kernel/cred.o.new
    2788 336 8 3132 c3c kernel/cred.o.old

    Miscellanea:
    o Neaten the #define kdebug macros while there

    Signed-off-by: Joe Perches
    Cc: David Howells
    Cc: James Morris
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Joe Perches
     
  • Signed-off-by: Wei Yongjun
    Acked-by: Steven Rostedt
    Cc: Thomas Gleixner
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Wei Yongjun
     

10 Sep, 2015

2 commits

  • when the verifier log is enabled the print_bpf_insn() is doing
    bpf_alu_string[BPF_OP(insn->code) >> 4]
    and
    bpf_jmp_string[BPF_OP(insn->code) >> 4]
    where BPF_OP is a 4-bit instruction opcode.
    Malformed insns can cause out of bounds access.
    Fix it by sizing arrays appropriately.

    The bug was found by clang address sanitizer with libfuzzer.

    Reported-by: Yonghong Song
    Signed-off-by: Alexei Starovoitov
    Acked-by: Daniel Borkmann
    Signed-off-by: David S. Miller

    Alexei Starovoitov
     
  • We may already have gotten a proper fd struct through fdget(), so
    whenever we return at the end of an map operation, we need to call
    fdput(). However, each map operation from syscall side first probes
    CHECK_ATTR() to verify that unused fields in the bpf_attr union are
    zero.

    In case of malformed input, we return with error, but the lookup to
    the map_fd was already performed at that time, so that we return
    without an corresponding fdput(). Fix it by performing an fdget()
    only right before bpf_map_get(). The fdget() invocation on maps in
    the verifier is not affected.

    Fixes: db20fd2b0108 ("bpf: add lookup/update/delete/iterate methods to BPF maps")
    Signed-off-by: Daniel Borkmann
    Acked-by: Alexei Starovoitov
    Signed-off-by: David S. Miller

    Daniel Borkmann
     

09 Sep, 2015

3 commits

  • Merge second patch-bomb from Andrew Morton:
    "Almost all of the rest of MM. There was an unusually large amount of
    MM material this time"

    * emailed patches from Andrew Morton : (141 commits)
    zpool: remove no-op module init/exit
    mm: zbud: constify the zbud_ops
    mm: zpool: constify the zpool_ops
    mm: swap: zswap: maybe_preload & refactoring
    zram: unify error reporting
    zsmalloc: remove null check from destroy_handle_cache()
    zsmalloc: do not take class lock in zs_shrinker_count()
    zsmalloc: use class->pages_per_zspage
    zsmalloc: consider ZS_ALMOST_FULL as migrate source
    zsmalloc: partial page ordering within a fullness_list
    zsmalloc: use shrinker to trigger auto-compaction
    zsmalloc: account the number of compacted pages
    zsmalloc/zram: introduce zs_pool_stats api
    zsmalloc: cosmetic compaction code adjustments
    zsmalloc: introduce zs_can_compact() function
    zsmalloc: always keep per-class stats
    zsmalloc: drop unused variable `nr_to_migrate'
    mm/memblock.c: fix comment in __next_mem_range()
    mm/page_alloc.c: fix type information of memoryless node
    memory-hotplug: fix comments in zone_spanned_pages_in_node() and zone_spanned_pages_in_node()
    ...

    Linus Torvalds
     
  • alloc_pages_exact_node() was introduced in commit 6484eb3e2a81 ("page
    allocator: do not check NUMA node ID when the caller knows the node is
    valid") as an optimized variant of alloc_pages_node(), that doesn't
    fallback to current node for nid == NUMA_NO_NODE. Unfortunately the
    name of the function can easily suggest that the allocation is
    restricted to the given node and fails otherwise. In truth, the node is
    only preferred, unless __GFP_THISNODE is passed among the gfp flags.

    The misleading name has lead to mistakes in the past, see for example
    commits 5265047ac301 ("mm, thp: really limit transparent hugepage
    allocation to local node") and b360edb43f8e ("mm, mempolicy:
    migrate_to_node should only migrate to node").

    Another issue with the name is that there's a family of
    alloc_pages_exact*() functions where 'exact' means exact size (instead
    of page order), which leads to more confusion.

    To prevent further mistakes, this patch effectively renames
    alloc_pages_exact_node() to __alloc_pages_node() to better convey that
    it's an optimized variant of alloc_pages_node() not intended for general
    usage. Both functions get described in comments.

    It has been also considered to really provide a convenience function for
    allocations restricted to a node, but the major opinion seems to be that
    __GFP_THISNODE already provides that functionality and we shouldn't
    duplicate the API needlessly. The number of users would be small
    anyway.

    Existing callers of alloc_pages_exact_node() are simply converted to
    call __alloc_pages_node(), with the exception of sba_alloc_coherent()
    which open-codes the check for NUMA_NO_NODE, so it is converted to use
    alloc_pages_node() instead. This means it no longer performs some
    VM_BUG_ON checks, and since the current check for nid in
    alloc_pages_node() uses a 'nid < 0' comparison (which includes
    NUMA_NO_NODE), it may hide wrong values which would be previously
    exposed.

    Both differences will be rectified by the next patch.

    To sum up, this patch makes no functional changes, except temporarily
    hiding potentially buggy callers. Restricting the checks in
    alloc_pages_node() is left for the next patch which can in turn expose
    more existing buggy callers.

    Signed-off-by: Vlastimil Babka
    Acked-by: Johannes Weiner
    Acked-by: Robin Holt
    Acked-by: Michal Hocko
    Acked-by: Christoph Lameter
    Acked-by: Michael Ellerman
    Cc: Mel Gorman
    Cc: David Rientjes
    Cc: Greg Thelen
    Cc: Aneesh Kumar K.V
    Cc: Pekka Enberg
    Cc: Joonsoo Kim
    Cc: Naoya Horiguchi
    Cc: Tony Luck
    Cc: Fenghua Yu
    Cc: Arnd Bergmann
    Cc: Benjamin Herrenschmidt
    Cc: Paul Mackerras
    Cc: Gleb Natapov
    Cc: Paolo Bonzini
    Cc: Thomas Gleixner
    Cc: Ingo Molnar
    Cc: "H. Peter Anvin"
    Cc: Cliff Whickman
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Vlastimil Babka
     
  • When seq_show_option (commit a068acf2ee77: "fs: create and use
    seq_show_option for escaping") was merged, it did not correctly collide
    with cgroup's addition of legacy_name (commit 3e1d2eed39d8: "cgroup:
    introduce cgroup_subsys->legacy_name") changes.

    This fixes the reported name.

    Signed-off-by: Kees Cook
    Acked-by: Tejun Heo
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kees Cook