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linux-next/kernel/locking
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Davidlohr Bueso 6687659568 locking/pvqspinlock: Fix division by zero in qstat_read() 
While playing with the qstat statistics (in <debugfs>/qlockstat/) I ran into
the following splat on a VM when opening pv_hash_hops:

  divide error: 0000 [#1] SMP
  ...
  RIP: 0010:[<ffffffff810b61fe>]  [<ffffffff810b61fe>] qstat_read+0x12e/0x1e0
  ...
  Call Trace:
    [<ffffffff811cad7c>] ? mem_cgroup_commit_charge+0x6c/0xd0
    [<ffffffff8119750c>] ? page_add_new_anon_rmap+0x8c/0xd0
    [<ffffffff8118d3b9>] ? handle_mm_fault+0x1439/0x1b40
    [<ffffffff811937a9>] ? do_mmap+0x449/0x550
    [<ffffffff811d3de3>] ? __vfs_read+0x23/0xd0
    [<ffffffff811d4ab2>] ? rw_verify_area+0x52/0xd0
    [<ffffffff811d4bb1>] ? vfs_read+0x81/0x120
    [<ffffffff811d5f12>] ? SyS_read+0x42/0xa0
    [<ffffffff815720f6>] ? entry_SYSCALL_64_fastpath+0x1e/0xa8

Fix this by verifying that qstat_pv_kick_unlock is in fact non-zero,
similarly to what the qstat_pv_latency_wake case does, as if nothing
else, this can come from resetting the statistics, thus having 0 kicks
should be quite valid in this context.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Waiman Long <Waiman.Long@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: waiman.long@hpe.com
Link: http://lkml.kernel.org/r/1460961103-24953-1-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-19 10:49:19 +02:00
..
lglock.c sched/stop_machine: Fix deadlock between multiple stop_two_cpus() 2015-06-19 10:03:12 +02:00
lockdep_internals.h lockdep: Increase static allocations 2014-04-18 14:20:50 +02:00
lockdep_proc.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
lockdep_states.h locking: Move the lockdep code to kernel/locking/ 2013-11-06 07:55:08 +01:00
lockdep.c locking/lockdep: Fix print_collision() unused warning 2016-04-04 11:41:34 +02:00
locktorture.c Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and 'torture.2015.10.06a' into HEAD 2015-10-07 16:06:25 -07:00
Makefile kernel: add kcov code coverage 2016-03-22 15:36:02 -07:00
mcs_spinlock.h locking/mcs: Fix mcs_spin_lock() ordering 2016-02-29 10:02:41 +01:00
mutex-debug.c mutex: Always clear owner field upon mutex_unlock() 2015-01-09 11:20:39 +01:00
mutex-debug.h
mutex.c locking/mutex: Allow next waiter lockless wakeup 2016-02-29 10:02:42 +01:00
mutex.h locking/mutexes: Use MUTEX_SPIN_ON_OWNER when appropriate 2014-08-13 10:32:02 +02:00
osq_lock.c locking/osq: Fix ordering of node initialisation in osq_lock 2015-12-17 11:40:29 -08:00
percpu-rwsem.c locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read() 2015-10-06 11:25:40 -07:00
qrwlock.c locking/qrwlock: Rename ->lock to ->wait_lock 2015-09-18 09:27:29 +02:00
qspinlock_paravirt.h locking/pvqspinlock: Enable slowpath locking count tracking 2016-02-29 10:02:42 +01:00
qspinlock_stat.h locking/pvqspinlock: Fix division by zero in qstat_read() 2016-04-19 10:49:19 +02:00
qspinlock.c locking/qspinlock: Use smp_cond_acquire() in pending code 2016-02-29 10:02:42 +01:00
rtmutex_common.h rtmutex: Delete scriptable tester 2015-07-20 11:45:45 +02:00
rtmutex-debug.c rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rtmutex-debug.h rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rtmutex.c rtmutex: Make wait_lock irq safe 2016-01-26 11:08:35 +01:00
rtmutex.h rtmutex: Cleanup deadlock detector debug logic 2014-06-21 22:05:30 +02:00
rwsem-spinlock.c locking/rwsem: Document barrier need when waking tasks 2015-02-18 16:57:10 +01:00
rwsem-xadd.c locking/rwsem: Use acquire/release semantics 2015-10-06 17:28:24 +02:00
rwsem.c locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
rwsem.h locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
semaphore.c locking/semaphore: Resolve some shadow warnings 2014-09-04 07:17:24 +02:00
spinlock_debug.c locking: Move the spinlock code to kernel/locking/ 2013-11-06 07:55:21 +01:00
spinlock.c spinlock: Add spin_lock_bh_nested() 2015-01-03 14:32:57 -05:00