valid_state() and print_usage_bug*() functions are not used beyond
irq locking correctness checks under CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING.
Sadly the "unused function" warning wouldn't fire because valid_state()
is inline so the unused case has remained unseen until now.
So move them inside the appropriate CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
section.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190402160244.32434-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If lockdep_register_key() and lockdep_unregister_key() are called with
debug_locks == false then the following warning is reported:
WARNING: CPU: 2 PID: 15145 at kernel/locking/lockdep.c:4920 lockdep_unregister_key+0x1ad/0x240
That warning is reported because lockdep_unregister_key() ignores the
value of 'debug_locks' and because the behavior of lockdep_register_key()
depends on whether or not 'debug_locks' is set. Fix this inconsistency
by making lockdep_unregister_key() take 'debug_locks' again into
account.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: shenghui <shhuiw@foxmail.com>
Fixes: 90c1cba2b3 ("locking/lockdep: Zap lock classes even with lock debugging disabled")
Link: http://lkml.kernel.org/r/20190415170538.23491-1-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
No architecture terminates the stack trace with ULONG_MAX anymore. Remove
the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190410103644.485737321@linutronix.de
The following commit:
a0b0fd53e1 ("locking/lockdep: Free lock classes that are no longer in use")
changed the behavior of lockdep_free_key_range() from
unconditionally zapping lock classes into only zapping lock classes if
debug_lock == true. Not zapping lock classes if debug_lock == false leaves
dangling pointers in several lockdep datastructures, e.g. lock_class::name
in the all_lock_classes list.
The shell command "cat /proc/lockdep" causes the kernel to iterate the
all_lock_classes list. Hence the "unable to handle kernel paging request" cash
that Shenghui encountered by running cat /proc/lockdep.
Since the new behavior can cause cat /proc/lockdep to crash, restore the
pre-v5.1 behavior.
This patch avoids that cat /proc/lockdep triggers the following crash
with debug_lock == false:
BUG: unable to handle kernel paging request at fffffbfff40ca448
RIP: 0010:__asan_load1+0x28/0x50
Call Trace:
string+0xac/0x180
vsnprintf+0x23e/0x820
seq_vprintf+0x82/0xc0
seq_printf+0x92/0xb0
print_name+0x34/0xb0
l_show+0x184/0x200
seq_read+0x59e/0x6c0
proc_reg_read+0x11f/0x170
__vfs_read+0x4d/0x90
vfs_read+0xc5/0x1f0
ksys_read+0xab/0x130
__x64_sys_read+0x43/0x50
do_syscall_64+0x71/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reported-by: shenghui <shhuiw@foxmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: a0b0fd53e1 ("locking/lockdep: Free lock classes that are no longer in use") # v5.1-rc1.
Link: https://lkml.kernel.org/r/20190403233552.124673-1-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add lock event counting calls so that we can track the number of lock
events happening in the rwsem code.
With CONFIG_LOCK_EVENT_COUNTS on and booting a 4-socket 112-thread x86-64
system, the rwsem counts after system bootup were as follows:
rwsem_opt_fail=261
rwsem_opt_wlock=50636
rwsem_rlock=445
rwsem_rlock_fail=0
rwsem_rlock_fast=22
rwsem_rtrylock=810144
rwsem_sleep_reader=441
rwsem_sleep_writer=310
rwsem_wake_reader=355
rwsem_wake_writer=2335
rwsem_wlock=261
rwsem_wlock_fail=0
rwsem_wtrylock=20583
It can be seen that most of the lock acquisitions in the slowpath were
write-locks in the optimistic spinning code path with no sleeping at
all. For this system, over 97% of the locks are acquired via optimistic
spinning. It illustrates the importance of optimistic spinning in
improving the performance of rwsem.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-11-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On bare metal, the pvqspinlock event counts will always be 0. So there
is no point in showing their corresponding debugfs files. So they are
skipped in this case.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-10-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The QUEUED_LOCK_STAT option to report queued spinlocks event counts
was previously allowed only on x86 architecture. To make the locking
event counting code more useful, it is now renamed to a more generic
LOCK_EVENT_COUNTS config option. This new option will be available to
all the architectures that use qspinlock at the moment.
Other locking code can now start to use the generic locking event
counting code by including lock_events.h and put the new locking event
names into the lock_events_list.h header file.
My experience with lock event counting is that it gives valuable insight
on how the locking code works and what can be done to make it better. I
would like to extend this benefit to other locking code like mutex and
rwsem in the near future.
The PV qspinlock specific code will stay in qspinlock_stat.h. The
locking event counters will now reside in the <debugfs>/lock_event_counts
directory.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-9-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The percpu event counts used by qspinlock code can be useful for
other locking code as well. So a new set of lockevent_* counting APIs
is introduced with the lock event names extracted out into the new
lock_events_list.h header file for easier addition in the future.
The existing qstat_inc() calls are replaced by either lockevent_inc() or
lockevent_cond_inc() calls.
The qstat_hop() call is renamed to lockevent_pv_hop(). The "reset_counters"
debugfs file is also renamed to ".reset_counts".
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-8-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the DEBUG_RWSEMS_WARN_ON() macro just dumps a stack trace
when the rwsem isn't in the right state. It does not show the actual
states of the rwsem. This may not be that helpful in the debugging
process.
Enhance the DEBUG_RWSEMS_WARN_ON() macro to also show the current
content of the rwsem count and owner fields to give more information
about what is wrong with the rwsem. The debug_locks_off() function is
called as is done inside DEBUG_LOCKS_WARN_ON().
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-7-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When rwsem_down_read_failed*() return, the read lock is acquired
indirectly by others. So debug checks are added in __down_read() and
__down_read_killable() to make sure the rwsem is really reader-owned.
The other debug check calls in kernel/locking/rwsem.c except the
one in up_read_non_owner() are also moved over to rwsem-xadd.h.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-6-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The atomic_long_cmpxchg_acquire() in rwsem_try_read_lock_unqueued() is
replaced by atomic_long_try_cmpxchg_acquire() to simpify the code and
generate slightly better assembly code.
There is no functional change.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-5-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We don't need to expose rwsem internal functions which are not supposed
to be called directly from other kernel code.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-4-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move all the owner setting code closer to the rwsem-xadd fast paths
directly within rwsem.h file as well as in the slowpaths where owner
setting is done after acquring the lock. This will enable us to add
DEBUG_RWSEMS check in a later patch to make sure that read lock is
really acquired when rwsem_down_read_failed() returns, for instance.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-3-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The rwsem_down_read_failed*() functions were relocated from above the
optimistic spinning section to below that section. This enables the
reader functions to use optimisitic spinning in future patches. There
is no code change.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-2-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Removing explicit calls to mmiowb() from driver code means that we must
now call into the generic mmiowb_spin_{lock,unlock}() functions from the
core spinlock code. In order to elide barriers following critical
sections without any I/O writes, we also hook into the asm-generic I/O
routines.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
In preparation for removing all explicit mmiowb() calls from driver
code, implement a tracking system in asm-generic based loosely on the
PowerPC implementation. This allows architectures with a non-empty
mmiowb() definition to have the barrier automatically inserted in
spin_unlock() following a critical section containing an I/O write.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Currently, we have two different implementation of rwsem:
1) CONFIG_RWSEM_GENERIC_SPINLOCK (rwsem-spinlock.c)
2) CONFIG_RWSEM_XCHGADD_ALGORITHM (rwsem-xadd.c)
As we are going to use a single generic implementation for rwsem-xadd.c
and no architecture-specific code will be needed, there is no point
in keeping two different implementations of rwsem. In most cases, the
performance of rwsem-spinlock.c will be worse. It also doesn't get all
the performance tuning and optimizations that had been implemented in
rwsem-xadd.c over the years.
For simplication, we are going to remove rwsem-spinlock.c and make all
architectures use a single implementation of rwsem - rwsem-xadd.c.
All references to RWSEM_GENERIC_SPINLOCK and RWSEM_XCHGADD_ALGORITHM
in the code are removed.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Link: https://lkml.kernel.org/r/20190322143008.21313-3-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As the generic rwsem-xadd code is using the appropriate acquire and
release versions of the atomic operations, the arch specific rwsem.h
files will not be that much faster than the generic code as long as the
atomic functions are properly implemented. So we can remove those arch
specific rwsem.h and stop building asm/rwsem.h to reduce maintenance
effort.
Currently, only x86, alpha and ia64 have implemented architecture
specific fast paths. I don't have access to alpha and ia64 systems for
testing, but they are legacy systems that are not likely to be updated
to the latest kernel anyway.
By using a rwsem microbenchmark, the total locking rates on a 4-socket
56-core 112-thread x86-64 system before and after the patch were as
follows (mixed means equal # of read and write locks):
Before Patch After Patch
# of Threads wlock rlock mixed wlock rlock mixed
------------ ----- ----- ----- ----- ----- -----
1 29,201 30,143 29,458 28,615 30,172 29,201
2 6,807 13,299 1,171 7,725 15,025 1,804
4 6,504 12,755 1,520 7,127 14,286 1,345
8 6,762 13,412 764 6,826 13,652 726
16 6,693 15,408 662 6,599 15,938 626
32 6,145 15,286 496 5,549 15,487 511
64 5,812 15,495 60 5,858 15,572 60
There were some run-to-run variations for the multi-thread tests. For
x86-64, using the generic C code fast path seems to be a little bit
faster than the assembly version with low lock contention. Looking at
the assembly version of the fast paths, there are assembly to/from C
code wrappers that save and restore all the callee-clobbered registers
(7 registers on x86-64). The assembly generated from the generic C
code doesn't need to do that. That may explain the slight performance
gain here.
The generic asm rwsem.h can also be merged into kernel/locking/rwsem.h
with no code change as no other code other than those under
kernel/locking needs to access the internal rwsem macros and functions.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Link: https://lkml.kernel.org/r/20190322143008.21313-2-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, lock_torture_cleanup() uses the values of cxt.lwsa and cxt.lrsa
to detect bad parameters that prevented locktorture from initializing,
let alone running. In this case, lock_torture_cleanup() does no cleanup
aside from invoking torture_cleanup_begin() and torture_cleanup_end(),
as required to permit future torture tests to run. However, this
heuristic fails if the run with bad parameters was preceded by a previous
run that actually ran: In this case, both cxt.lwsa and cxt.lrsa will
remain non-zero, which means that the current lock_torture_cleanup()
invocation will be unable to detect the fact that it should skip cleanup,
which can result in charming outcomes such as double frees.
This commit therefore NULLs out both cxt.lwsa and cxt.lrsa at the end
of any run that actually ran.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Josh Triplett <josh@joshtriplett.org>
init_data_structures_once() is called for the first time before RCU has
been initialized. Make sure that init_rcu_head() is called before the
RCU head is used and after RCU has been initialized.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/c20aa0f0-42ab-a884-d931-7d4ec2bf0cdc@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Clang warns about a tentative array definition without a length:
kernel/locking/lockdep.c:845:12: error: tentative array definition assumed to have one element [-Werror]
There is no real reason to do this here, so just set the same length as
in the real definition later in the same file. It has to be hidden in
an #ifdef or annotated __maybe_unused though, to avoid the unused-variable
warning if CONFIG_PROVE_LOCKING is disabled.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190307075222.3424524-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf updates from Ingo Molnar:
"Lots of tooling updates - too many to list, here's a few highlights:
- Various subcommand updates to 'perf trace', 'perf report', 'perf
record', 'perf annotate', 'perf script', 'perf test', etc.
- CPU and NUMA topology and affinity handling improvements,
- HW tracing and HW support updates:
- Intel PT updates
- ARM CoreSight updates
- vendor HW event updates
- BPF updates
- Tons of infrastructure updates, both on the build system and the
library support side
- Documentation updates.
- ... and lots of other changes, see the changelog for details.
Kernel side updates:
- Tighten up kprobes blacklist handling, reduce the number of places
where developers can install a kprobe and hang/crash the system.
- Fix/enhance vma address filter handling.
- Various PMU driver updates, small fixes and additions.
- refcount_t conversions
- BPF updates
- error code propagation enhancements
- misc other changes"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (238 commits)
perf script python: Add Python3 support to syscall-counts-by-pid.py
perf script python: Add Python3 support to syscall-counts.py
perf script python: Add Python3 support to stat-cpi.py
perf script python: Add Python3 support to stackcollapse.py
perf script python: Add Python3 support to sctop.py
perf script python: Add Python3 support to powerpc-hcalls.py
perf script python: Add Python3 support to net_dropmonitor.py
perf script python: Add Python3 support to mem-phys-addr.py
perf script python: Add Python3 support to failed-syscalls-by-pid.py
perf script python: Add Python3 support to netdev-times.py
perf tools: Add perf_exe() helper to find perf binary
perf script: Handle missing fields with -F +..
perf data: Add perf_data__open_dir_data function
perf data: Add perf_data__(create_dir|close_dir) functions
perf data: Fail check_backup in case of error
perf data: Make check_backup work over directories
perf tools: Add rm_rf_perf_data function
perf tools: Add pattern name checking to rm_rf
perf tools: Add depth checking to rm_rf
perf data: Add global path holder
...
Pull locking updates from Ingo Molnar:
"The biggest part of this tree is the new auto-generated atomics API
wrappers by Mark Rutland.
The primary motivation was to allow instrumentation without uglifying
the primary source code.
The linecount increase comes from adding the auto-generated files to
the Git space as well:
include/asm-generic/atomic-instrumented.h | 1689 ++++++++++++++++--
include/asm-generic/atomic-long.h | 1174 ++++++++++---
include/linux/atomic-fallback.h | 2295 +++++++++++++++++++++++++
include/linux/atomic.h | 1241 +------------
I preferred this approach, so that the full call stack of the (already
complex) locking APIs is still fully visible in 'git grep'.
But if this is excessive we could certainly hide them.
There's a separate build-time mechanism to determine whether the
headers are out of date (they should never be stale if we do our job
right).
Anyway, nothing from this should be visible to regular kernel
developers.
Other changes:
- Add support for dynamic keys, which removes a source of false
positives in the workqueue code, among other things (Bart Van
Assche)
- Updates to tools/memory-model (Andrea Parri, Paul E. McKenney)
- qspinlock, wake_q and lockdep micro-optimizations (Waiman Long)
- misc other updates and enhancements"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
locking/lockdep: Shrink struct lock_class_key
locking/lockdep: Add module_param to enable consistency checks
lockdep/lib/tests: Test dynamic key registration
lockdep/lib/tests: Fix run_tests.sh
kernel/workqueue: Use dynamic lockdep keys for workqueues
locking/lockdep: Add support for dynamic keys
locking/lockdep: Verify whether lock objects are small enough to be used as class keys
locking/lockdep: Check data structure consistency
locking/lockdep: Reuse lock chains that have been freed
locking/lockdep: Fix a comment in add_chain_cache()
locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count()
locking/lockdep: Reuse list entries that are no longer in use
locking/lockdep: Free lock classes that are no longer in use
locking/lockdep: Update two outdated comments
locking/lockdep: Make it easy to detect whether or not inside a selftest
locking/lockdep: Split lockdep_free_key_range() and lockdep_reset_lock()
locking/lockdep: Initialize the locks_before and locks_after lists earlier
locking/lockdep: Make zap_class() remove all matching lock order entries
locking/lockdep: Reorder struct lock_class members
locking/lockdep: Avoid that add_chain_cache() adds an invalid chain to the cache
...
And move the whole lot under CONFIG_DEBUG_LOCKDEP.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A shortcoming of the current lockdep implementation is that it requires
lock keys to be allocated statically. That forces all instances of lock
objects that occur in a given data structure to share a lock key. Since
lock dependency analysis groups lock objects per key sharing lock keys
can cause false positive lockdep reports. Make it possible to avoid
such false positive reports by allowing lock keys to be allocated
dynamically. Require that dynamically allocated lock keys are
registered before use by calling lockdep_register_key(). Complain about
attempts to register the same lock key pointer twice without calling
lockdep_unregister_key() between successive registration calls.
The purpose of the new lock_keys_hash[] data structure that keeps
track of all dynamic keys is twofold:
- Verify whether the lockdep_register_key() and lockdep_unregister_key()
functions are used correctly.
- Avoid that lockdep_init_map() complains when encountering a dynamically
allocated key.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-19-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Debugging lockdep data structure inconsistencies is challenging. Add
code that verifies data structure consistency at runtime. That code is
disabled by default because it is very CPU intensive.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-17-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A previous patch introduced a lock chain leak. Fix that leak by reusing
lock chains that have been freed.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-16-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reflect that add_chain_cache() is always called with the graph lock held.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-15-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch does not change any functionality but makes the next patch in
this series easier to read.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-14-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of abandoning elements of list_entries[] that are no longer in
use, make alloc_list_entry() reuse array elements that have been freed.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-13-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of leaving lock classes that are no longer in use in the
lock_classes array, reuse entries from that array that are no longer in
use. Maintain a linked list of free lock classes with list head
'free_lock_class'. Only add freed lock classes to the free_lock_classes
list after a grace period to avoid that a lock_classes[] element would
be reused while an RCU reader is accessing it. Since the lockdep
selftests run in a context where sleeping is not allowed and since the
selftests require that lock resetting/zapping works with debug_locks
off, make the behavior of lockdep_free_key_range() and
lockdep_reset_lock() depend on whether or not these are called from
the context of the lockdep selftests.
Thanks to Peter for having shown how to modify get_pending_free()
such that that function does not have to sleep.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-12-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
synchronize_sched() has been removed recently. Update the comments that
refer to synchronize_sched().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Fixes: 51959d85f3 ("lockdep: Replace synchronize_sched() with synchronize_rcu()") # v5.0-rc1
Link: https://lkml.kernel.org/r/20190214230058.196511-11-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The patch that frees unused lock classes will modify the behavior of
lockdep_free_key_range() and lockdep_reset_lock() depending on whether
or not these functions are called from the context of the lockdep
selftests. Hence make it easy to detect whether or not lockdep code
is called from the context of a lockdep selftest.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-10-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch does not change the behavior of these functions but makes the
patch that frees unused lock classes easier to read.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-9-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch does not change any functionality. A later patch will reuse
lock classes that have been freed. In combination with that patch this
patch wil have the effect of initializing lock class order lists once
instead of every time a lock class structure is reinitialized.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-8-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make sure that all lock order entries that refer to a class are removed
from the list_entries[] array when a kernel module is unloaded.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-7-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make sure that add_chain_cache() returns 0 and does not modify the
chain hash if nr_chain_hlocks == MAX_LOCKDEP_CHAIN_HLOCKS before this
function is called.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-5-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Lock chains are only tracked with CONFIG_PROVE_LOCKING=y. Do not report
the memory required for the lock chain array if CONFIG_PROVE_LOCKING=n.
See also commit:
ca58abcb4a ("lockdep: sanitise CONFIG_PROVE_LOCKING")
Include the size of the chain_hlocks[] array.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-4-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change the sizeof(array element time) * (array size) expressions into
sizeof(array). This fixes the size computations of the classhash_table[]
and chainhash_table[] arrays.
The reason is that commit:
a63f38cc4c ("locking/lockdep: Convert hash tables to hlists")
changed the type of the elements of that array from 'struct list_head' into
'struct hlist_head'.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-3-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use %zu to format size_t instead of %lu to avoid that the compiler
complains about a mismatch between format specifier and argument on
32-bit systems.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-2-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the > 4 nesting levels case handled by the commit:
d682b596d9 ("locking/qspinlock: Handle > 4 slowpath nesting levels")
the BUG_ON() call in encode_tail() will never actually be triggered.
Remove it.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.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>
Link: https://lkml.kernel.org/r/1551057253-3231-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull the latest RCU tree from Paul E. McKenney:
- Additional cleanups after RCU flavor consolidation
- Grace-period forward-progress cleanups and improvements
- Documentation updates
- Miscellaneous fixes
- spin_is_locked() conversions to lockdep
- SPDX changes to RCU source and header files
- SRCU updates
- Torture-test updates, including nolibc updates and moving
nolibc to tools/include
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some lockdep functions can be involved in breakpoint handling
and probing on those functions can cause a breakpoint recursion.
Prohibit probing on those functions by blacklist.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998810578.31052.1680977921449292812.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
commit 56222b212e ("futex: Drop hb->lock before enqueueing on the
rtmutex") changed the locking rules in the futex code so that the hash
bucket lock is not longer held while the waiter is enqueued into the
rtmutex wait list. This made the lock and the unlock path symmetric, but
unfortunately the possible early exit from __rt_mutex_proxy_start() due to
a detected deadlock was not updated accordingly. That allows a concurrent
unlocker to observe inconsitent state which triggers the warning in the
unlock path.
futex_lock_pi() futex_unlock_pi()
lock(hb->lock)
queue(hb_waiter) lock(hb->lock)
lock(rtmutex->wait_lock)
unlock(hb->lock)
// acquired hb->lock
hb_waiter = futex_top_waiter()
lock(rtmutex->wait_lock)
__rt_mutex_proxy_start()
---> fail
remove(rtmutex_waiter);
---> returns -EDEADLOCK
unlock(rtmutex->wait_lock)
// acquired wait_lock
wake_futex_pi()
rt_mutex_next_owner()
--> returns NULL
--> WARN
lock(hb->lock)
unqueue(hb_waiter)
The problem is caused by the remove(rtmutex_waiter) in the failure case of
__rt_mutex_proxy_start() as this lets the unlocker observe a waiter in the
hash bucket but no waiter on the rtmutex, i.e. inconsistent state.
The original commit handles this correctly for the other early return cases
(timeout, signal) by delaying the removal of the rtmutex waiter until the
returning task reacquired the hash bucket lock.
Treat the failure case of __rt_mutex_proxy_start() in the same way and let
the existing cleanup code handle the eventual handover of the rtmutex
gracefully. The regular rt_mutex_proxy_start() gains the rtmutex waiter
removal for the failure case, so that the other callsites are still
operating correctly.
Add proper comments to the code so all these details are fully documented.
Thanks to Peter for helping with the analysis and writing the really
valuable code comments.
Fixes: 56222b212e ("futex: Drop hb->lock before enqueueing on the rtmutex")
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Co-developed-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Stefan Liebler <stli@linux.ibm.com>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1901292311410.1950@nanos.tec.linutronix.de
Track the number of slowpath locking operations that are being done
without any MCS node available as well renaming lock_index[123] to make
them more descriptive.
Using these stat counters is one way to find out if a code path is
being exercised.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: James Morse <james.morse@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: SRINIVAS <srinivas.eeda@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Link: https://lkml.kernel.org/r/1548798828-16156-3-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Four queue nodes per CPU are allocated to enable up to 4 nesting levels
using the per-CPU nodes. Nested NMIs are possible in some architectures.
Still it is very unlikely that we will ever hit more than 4 nested
levels with contention in the slowpath.
When that rare condition happens, however, it is likely that the system
will hang or crash shortly after that. It is not good and we need to
handle this exception case.
This is done by spinning directly on the lock using repeated trylock.
This alternative code path should only be used when there is nested
NMIs. Assuming that the locks used by those NMI handlers will not be
heavily contended, a simple TAS locking should work out.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: James Morse <james.morse@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: SRINIVAS <srinivas.eeda@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Link: https://lkml.kernel.org/r/1548798828-16156-2-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some users, specifically futexes and rwsems, required fixes
that allowed the callers to be safe when wakeups occur before
they are expected by wake_up_q(). Such scenarios also play
games and rely on reference counting, and until now were
pivoting on wake_q doing it. With the wake_q_add() call being
moved down, this can no longer be the case. As such we end up
with a a double task refcounting overhead; and these callers
care enough about this (being rather core-ish).
This patch introduces a wake_q_add_safe() call that serves
for callers that have already done refcounting and therefore the
task is 'safe' from wake_q point of view (int that it requires
reference throughout the entire queue/>wakeup cycle). In the one
case it has internal reference counting, in the other case it
consumes the reference counting.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Xie Yongji <xieyongji@baidu.com>
Cc: Yongji Xie <elohimes@gmail.com>
Cc: andrea.parri@amarulasolutions.com
Cc: lilin24@baidu.com
Cc: liuqi16@baidu.com
Cc: nixun@baidu.com
Cc: yuanlinsi01@baidu.com
Cc: zhangyu31@baidu.com
Link: https://lkml.kernel.org/r/20181218195352.7orq3upiwfdbrdne@linux-r8p5
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.
Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Beyond a certain point in the CPU-hotplug offline process, timers get
stranded on the outgoing CPU, and won't fire until that CPU comes back
online, which might well be never. This commit therefore adds a hook
in torture_onoff_init() that is invoked from torture_offline(), which
rcutorture uses to occasionally wait for a grace period. This should
result in failures for RCU implementations that rely on stranded timers
eventually firing in the absence of the CPU coming back online.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
It makes the code more self-explanatory and tells throughout the code
what magic number refers to:
- state (Hardirq/Softirq)
- direction (used in or enabled above state)
- read or write
We can even remove some comments that were compensating for the lack of
those constant names.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1545973321-24422-3-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The enum mark_type appears a bit artificial here. We can directly pass
the base enum lock_usage_bit value to mark_held_locks(). All we need
then is to add the read index for each lock if necessary. It makes the
code clearer.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1545973321-24422-2-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.
Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().
Debugged-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because wake_q_add() can imply an immediate wakeup (cmpxchg failure
case), we must not rely on the wakeup being delayed. However, commit:
e38513905e ("locking/rwsem: Rework zeroing reader waiter->task")
relies on exactly that behaviour in that the wakeup must not happen
until after we clear waiter->task.
[ peterz: Added changelog. ]
Signed-off-by: Xie Yongji <xieyongji@baidu.com>
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: e38513905e ("locking/rwsem: Rework zeroing reader waiter->task")
Link: https://lkml.kernel.org/r/1543495830-2644-1-git-send-email-xieyongji@baidu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is already done for us internally by the signal machinery.
Link: http://lkml.kernel.org/r/20181116002713.8474-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull locking updates from Ingo Molnar:
"The main change in this cycle are initial preparatory bits of dynamic
lockdep keys support from Bart Van Assche.
There are also misc changes, a comment cleanup and a data structure
cleanup"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Clean up comment in nohz_idle_balance()
locking/lockdep: Stop using RCU primitives to access 'all_lock_classes'
locking/lockdep: Make concurrent lockdep_reset_lock() calls safe
locking/lockdep: Remove a superfluous INIT_LIST_HEAD() statement
locking/lockdep: Introduce lock_class_cache_is_registered()
locking/lockdep: Inline __lockdep_init_map()
locking/lockdep: Declare local symbols static
tools/lib/lockdep/tests: Test the lockdep_reset_lock() implementation
tools/lib/lockdep: Add dummy print_irqtrace_events() implementation
tools/lib/lockdep: Rename "trywlock" into "trywrlock"
tools/lib/lockdep/tests: Run lockdep tests a second time under Valgrind
tools/lib/lockdep/tests: Improve testing accuracy
tools/lib/lockdep/tests: Fix shellcheck warnings
tools/lib/lockdep/tests: Display compiler warning and error messages
locking/lockdep: Remove ::version from lock_class structure
Due to the previous patch all code that accesses the 'all_lock_classes'
list holds the graph lock. Hence use regular list primitives instead of
their RCU variants to access this list.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-14-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since zap_class() removes items from the all_lock_classes list and the
classhash_table, protect all zap_class() calls against concurrent
data structure modifications with the graph lock.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-13-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Initializing a list entry just before it is passed to list_add_tail_rcu()
is not necessary because list_add_tail_rcu() overwrites the next and prev
pointers anyway. Hence remove the INIT_LIST_HEAD() statement.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-12-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch does not change any functionality but makes the
lockdep_reset_lock() function easier to read.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-11-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the function __lockdep_init_map() only has one caller, inline it
into its caller. This patch does not change any functionality.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-10-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch avoids that sparse complains about a missing declaration for
the lock_classes array when building with CONFIG_DEBUG_LOCKDEP=n.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20181207011148.251812-9-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
bug.2018.11.12a: Get rid of BUG_ON() and friends
consolidate.2018.12.01a: Continued RCU flavor-consolidation cleanup
doc.2018.11.12a: Documentation updates
fixes.2018.11.12a: Miscellaneous fixes
initrd.2018.11.08b: Automate creation of rcutorture initrd
sil.2018.11.12a: Remove more spin_unlock_wait() calls
Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu(). This commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
lockdep_assert_held() is better suited to checking locking requirements,
since it only checks if the current thread holds the lock regardless of
whether someone else does. This is also a step towards possibly removing
spin_is_locked().
Signed-off-by: Lance Roy <ldr709@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Move remaining definitions and declarations from include/linux/bootmem.h
into include/linux/memblock.h and remove the redundant header.
The includes were replaced with the semantic patch below and then
semi-automated removal of duplicated '#include <linux/memblock.h>
@@
@@
- #include <linux/bootmem.h>
+ #include <linux/memblock.h>
[sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au
[sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au
[sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal]
Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au
Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Serge Semin <fancer.lancer@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull locking and misc x86 updates from Ingo Molnar:
"Lots of changes in this cycle - in part because locking/core attracted
a number of related x86 low level work which was easier to handle in a
single tree:
- Linux Kernel Memory Consistency Model updates (Alan Stern, Paul E.
McKenney, Andrea Parri)
- lockdep scalability improvements and micro-optimizations (Waiman
Long)
- rwsem improvements (Waiman Long)
- spinlock micro-optimization (Matthew Wilcox)
- qspinlocks: Provide a liveness guarantee (more fairness) on x86.
(Peter Zijlstra)
- Add support for relative references in jump tables on arm64, x86
and s390 to optimize jump labels (Ard Biesheuvel, Heiko Carstens)
- Be a lot less permissive on weird (kernel address) uaccess faults
on x86: BUG() when uaccess helpers fault on kernel addresses (Jann
Horn)
- macrofy x86 asm statements to un-confuse the GCC inliner. (Nadav
Amit)
- ... and a handful of other smaller changes as well"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
locking/lockdep: Make global debug_locks* variables read-mostly
locking/lockdep: Fix debug_locks off performance problem
locking/pvqspinlock: Extend node size when pvqspinlock is configured
locking/qspinlock_stat: Count instances of nested lock slowpaths
locking/qspinlock, x86: Provide liveness guarantee
x86/asm: 'Simplify' GEN_*_RMWcc() macros
locking/qspinlock: Rework some comments
locking/qspinlock: Re-order code
locking/lockdep: Remove duplicated 'lock_class_ops' percpu array
x86/defconfig: Enable CONFIG_USB_XHCI_HCD=y
futex: Replace spin_is_locked() with lockdep
locking/lockdep: Make class->ops a percpu counter and move it under CONFIG_DEBUG_LOCKDEP=y
x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs
x86/cpufeature: Macrofy inline assembly code to work around GCC inlining bugs
x86/extable: Macrofy inline assembly code to work around GCC inlining bugs
x86/paravirt: Work around GCC inlining bugs when compiling paravirt ops
x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs
x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs
x86/refcount: Work around GCC inlining bug
x86/objtool: Use asm macros to work around GCC inlining bugs
...
It was found that when debug_locks was turned off because of a problem
found by the lockdep code, the system performance could drop quite
significantly when the lock_stat code was also configured into the
kernel. For instance, parallel kernel build time on a 4-socket x86-64
server nearly doubled.
Further analysis into the cause of the slowdown traced back to the
frequent call to debug_locks_off() from the __lock_acquired() function
probably due to some inconsistent lockdep states with debug_locks
off. The debug_locks_off() function did an unconditional atomic xchg
to write a 0 value into debug_locks which had already been set to 0.
This led to severe cacheline contention in the cacheline that held
debug_locks. As debug_locks is being referenced in quite a few different
places in the kernel, this greatly slow down the system performance.
To prevent that trashing of debug_locks cacheline, lock_acquired()
and lock_contended() now checks the state of debug_locks before
proceeding. The debug_locks_off() function is also modified to check
debug_locks before calling __debug_locks_off().
Signed-off-by: Waiman Long <longman@redhat.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: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1539913518-15598-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The qspinlock code supports up to 4 levels of slowpath nesting using
four per-CPU mcs_spinlock structures. For 64-bit architectures, they
fit nicely in one 64-byte cacheline.
For para-virtualized (PV) qspinlocks it needs to store more information
in the per-CPU node structure than there is space for. It uses a trick
to use a second cacheline to hold the extra information that it needs.
So PV qspinlock needs to access two extra cachelines for its information
whereas the native qspinlock code only needs one extra cacheline.
Freshly added counter profiling of the qspinlock code, however, revealed
that it was very rare to use more than two levels of slowpath nesting.
So it doesn't make sense to penalize PV qspinlock code in order to have
four mcs_spinlock structures in the same cacheline to optimize for a case
in the native qspinlock code that rarely happens.
Extend the per-CPU node structure to have two more long words when PV
qspinlock locks are configured to hold the extra data that it needs.
As a result, the PV qspinlock code will enjoy the same benefit of using
just one extra cacheline like the native counterpart, for most cases.
[ mingo: Minor changelog edits. ]
Signed-off-by: Waiman Long <longman@redhat.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: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1539697507-28084-2-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Queued spinlock supports up to 4 levels of lock slowpath nesting -
user context, soft IRQ, hard IRQ and NMI. However, we are not sure how
often the nesting happens.
So add 3 more per-CPU stat counters to track the number of instances where
nesting index goes to 1, 2 and 3 respectively.
On a dual-socket 64-core 128-thread Zen server, the following were the
new stat counter values under different circumstances:
State slowpath index1 index2 index3
----- -------- ------ ------ -------
After bootup 1,012,150 82 0 0
After parallel build + perf-top 125,195,009 82 0 0
So the chance of having more than 2 levels of nesting is extremely low.
[ mingo: Minor changelog edits. ]
Signed-off-by: Waiman Long <longman@redhat.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: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1539697507-28084-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On x86 we cannot do fetch_or() with a single instruction and thus end up
using a cmpxchg loop, this reduces determinism. Replace the fetch_or()
with a composite operation: tas-pending + load.
Using two instructions of course opens a window we previously did not
have. Consider the scenario:
CPU0 CPU1 CPU2
1) lock
trylock -> (0,0,1)
2) lock
trylock /* fail */
3) unlock -> (0,0,0)
4) lock
trylock -> (0,0,1)
5) tas-pending -> (0,1,1)
load-val <- (0,1,0) from 3
6) clear-pending-set-locked -> (0,0,1)
FAIL: _2_ owners
where 5) is our new composite operation. When we consider each part of
the qspinlock state as a separate variable (as we can when
_Q_PENDING_BITS == 8) then the above is entirely possible, because
tas-pending will only RmW the pending byte, so the later load is able
to observe prior tail and lock state (but not earlier than its own
trylock, which operates on the whole word, due to coherence).
To avoid this we need 2 things:
- the load must come after the tas-pending (obviously, otherwise it
can trivially observe prior state).
- the tas-pending must be a full word RmW instruction, it cannot be an XCHGB for
example, such that we cannot observe other state prior to setting
pending.
On x86 we can realize this by using "LOCK BTS m32, r32" for
tas-pending followed by a regular load.
Note that observing later state is not a problem:
- if we fail to observe a later unlock, we'll simply spin-wait for
that store to become visible.
- if we observe a later xchg_tail(), there is no difference from that
xchg_tail() having taken place before the tas-pending.
Suggested-by: Will Deacon <will.deacon@arm.com>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: andrea.parri@amarulasolutions.com
Cc: longman@redhat.com
Fixes: 59fb586b4a ("locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpath")
Link: https://lkml.kernel.org/r/20181003130957.183726335@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While working my way through the code again; I felt the comments could
use help.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrea.parri@amarulasolutions.com
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/20181003130257.156322446@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Flip the branch condition after atomic_fetch_or_acquire(_Q_PENDING_VAL)
such that we loose the indent. This also result in a more natural code
flow IMO.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andrea.parri@amarulasolutions.com
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/20181003130257.156322446@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove the duplicated 'lock_class_ops' percpu array that is not used
anywhere.
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: 8ca2b56cd7 ("locking/lockdep: Make class->ops a percpu counter and move it under CONFIG_DEBUG_LOCKDEP=y")
Link: http://lkml.kernel.org/r/1539380547-16726-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A sizable portion of the CPU cycles spent on the __lock_acquire() is used
up by the atomic increment of the class->ops stat counter. By taking it out
from the lock_class structure and changing it to a per-cpu per-lock-class
counter, we can reduce the amount of cacheline contention on the class
structure when multiple CPUs are trying to acquire locks of the same
class simultaneously.
To limit the increase in memory consumption because of the percpu nature
of that counter, it is now put back under the CONFIG_DEBUG_LOCKDEP
config option. So the memory consumption increase will only occur if
CONFIG_DEBUG_LOCKDEP is defined. The lock_class structure, however,
is reduced in size by 16 bytes on 64-bit archs after ops removal and
a minor restructuring of the fields.
This patch also fixes a bug in the increment code as the counter is of
the 'unsigned long' type, but atomic_inc() was used to increment it.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/d66681f3-8781-9793-1dcf-2436a284550b@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If CONFIG_WW_MUTEX_SELFTEST=y is enabled, booting an image
in an arm64 virtual machine results in the following
traceback if 8 CPUs are enabled:
DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current)
WARNING: CPU: 2 PID: 537 at kernel/locking/mutex.c:1033 __mutex_unlock_slowpath+0x1a8/0x2e0
...
Call trace:
__mutex_unlock_slowpath()
ww_mutex_unlock()
test_cycle_work()
process_one_work()
worker_thread()
kthread()
ret_from_fork()
If requesting b_mutex fails with -EDEADLK, the error variable
is reassigned to the return value from calling ww_mutex_lock
on a_mutex again. If this call fails, a_mutex is not locked.
It is, however, unconditionally unlocked subsequently, causing
the reported warning. Fix the problem by using two error variables.
With this change, the selftest still fails as follows:
cyclic deadlock not resolved, ret[7/8] = -35
However, the traceback is gone.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: d1b42b800e ("locking/ww_mutex: Add kselftests for resolving ww_mutex cyclic deadlocks")
Link: http://lkml.kernel.org/r/1538516929-9734-1-git-send-email-linux@roeck-us.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When __lock_release() is called, the most likely unlock scenario is
on the innermost lock in the chain. In this case, we can skip some of
the checks and provide a faster path to completion.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1538511560-10090-4-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The static __lock_acquire() function has only two callers:
1) lock_acquire()
2) reacquire_held_locks()
In lock_acquire(), raw_local_irq_save() is called beforehand. So
IRQs must have been disabled. So the check:
DEBUG_LOCKS_WARN_ON(!irqs_disabled())
is kind of redundant in this case. So move the above check
to reacquire_held_locks() to eliminate redundant code in the
lock_acquire() path.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1538511560-10090-3-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The inline function add_chain_cache_classes() is defined, but has no
caller. Just remove it.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1538511560-10090-2-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merging v4.14.68 into v4.14-rt I tripped over a conflict in the
rtmutex.c code. There I found that we had:
#ifdef CONFIG_DEBUG_LOCK_ALLOC
[..]
#endif
#ifndef CONFIG_DEBUG_LOCK_ALLOC
[..]
#endif
Really this should be:
#ifdef CONFIG_DEBUG_LOCK_ALLOC
[..]
#else
[..]
#endif
This cleans up that logic.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Rosin <peda@axentia.se>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180910214638.55926030@vmware.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Trivial fix to spelling mistake in pr_err() error message
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20180824112235.8842-1-colin.king@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
c3bc8fd637 ("tracing: Centralize preemptirq tracepoints and unify their usage")
added the inclusion of <trace/events/preemptirq.h>.
liblockdep doesn't have a stub version of that header so now fails to build.
However, commit:
bff1b208a5 ("tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage"")
removed the use of functions declared in that header. So delete the #include.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <alexander.levin@verizon.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: bff1b208a5 ("tracing: Partial revert of "tracing: Centralize ...")
Fixes: c3bc8fd637 ("tracing: Centralize preemptirq tracepoints ...")
Link: http://lkml.kernel.org/r/20180828203315.GD18030@decadent.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, when a reader acquires a lock, it only sets the
RWSEM_READER_OWNED bit in the owner field. The other bits are simply
not used. When debugging hanging cases involving rwsems and readers,
the owner value does not provide much useful information at all.
This patch modifies the current behavior to always store the task_struct
pointer of the last rwsem-acquiring reader in a reader-owned rwsem. This
may be useful in debugging rwsem hanging cases especially if only one
reader is involved. However, the task in the owner field may not the
real owner or one of the real owners at all when the owner value is
examined, for example, in a crash dump. So it is just an additional
hint about the past history.
If CONFIG_DEBUG_RWSEMS=y is enabled, the owner field will be checked at
unlock time too to make sure the task pointer value is valid. That does
have a slight performance cost and so is only enabled as part of that
debug option.
From the performance point of view, it is expected that the changes
shouldn't have any noticeable performance impact. A rwsem microbenchmark
(with 48 worker threads and 1:1 reader/writer ratio) was ran on a
2-socket 24-core 48-thread Haswell system. The locking rates on a
4.19-rc1 based kernel were as follows:
1) Unpatched kernel: 543.3 kops/s
2) Patched kernel: 549.2 kops/s
3) Patched kernel (CONFIG_DEBUG_RWSEMS on): 546.6 kops/s
There was actually a slight increase in performance (1.1%) in this
particular case. Maybe it was caused by the elimination of a branch or
just a testing noise. Turning on the CONFIG_DEBUG_RWSEMS option also
had less than the expected impact on performance.
The least significant 2 bits of the owner value are now used to designate
the rwsem is readers owned and the owners are anonymous.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1536265114-10842-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was discovered that a constant stream of readers with occassional
writers pounding on a rwsem may cause many of the readers to enter the
slowpath unnecessarily thus increasing latency and lowering performance.
In the current code, a reader entering the slowpath critical section
will unconditionally set the WAITING_BIAS, if not set yet, and clear
its active count even if no one is in the wait queue and no writer
is present. This causes some incoming readers to observe the presence
of waiters in the wait queue and hence have to go into the slowpath
themselves.
With sufficient numbers of readers and a relatively short lock hold time,
the WAITING_BIAS may be repeatedly turned on and off and a substantial
portion of the readers will go into the slowpath sustaining a rather
long queue in the wait queue spinlock and repeated WAITING_BIAS on/off
cycle until the logjam is broken opportunistically.
To avoid this situation from happening, an additional check is added to
detect the special case that the reader in the critical section is the
only one in the wait queue and no writer is present. When that happens,
it can just exit the slowpath and return immediately as its active count
has already been set in the lock. Other incoming readers won't observe
the presence of waiters and so will not be forced into the slowpath.
The issue was found in a customer site where they had an application
that pounded on the pread64 syscalls heavily on an XFS filesystem. The
application was run in a recent 4-socket boxes with a lot of CPUs. They
saw significant spinlock contention in the rwsem_down_read_failed() call.
With this patch applied, the system CPU usage went down from 85% to 57%,
and the spinlock contention in the pread64 syscalls was gone.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1532459425-19204-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following commit:
08295b3b5b ("Implement an algorithm choice for Wound-Wait mutexes")
introduced a reference in the documentation to a function that was
removed in an earlier commit.
It also forgot to remove a call to debug_mutex_add_waiter() which is now
unconditionally called by __mutex_add_waiter().
Fix those bugs.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Fixes: 08295b3b5b ("Implement an algorithm choice for Wound-Wait mutexes")
Link: http://lkml.kernel.org/r/20180903140708.2401-1-thellstrom@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Restructure of lockdep and latency tracers
This is the biggest change. Joel Fernandes restructured the hooks
from irqs and preemption disabling and enabling. He got rid of
a lot of the preprocessor #ifdef mess that they caused.
He turned both lockdep and the latency tracers to use trace events
inserted in the preempt/irqs disabling paths. But unfortunately,
these started to cause issues in corner cases. Thus, parts of the
code was reverted back to where lockde and the latency tracers
just get called directly (without using the trace events).
But because the original change cleaned up the code very nicely
we kept that, as well as the trace events for preempt and irqs
disabling, but they are limited to not being called in NMIs.
- Have trace events use SRCU for "rcu idle" calls. This was required
for the preempt/irqs off trace events. But it also had to not
allow them to be called in NMI context. Waiting till Paul makes
an NMI safe SRCU API.
- New notrace SRCU API to allow trace events to use SRCU.
- Addition of mcount-nop option support
- SPDX headers replacing GPL templates.
- Various other fixes and clean ups.
- Some fixes are marked for stable, but were not fully tested
before the merge window opened.
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Merge tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- Restructure of lockdep and latency tracers
This is the biggest change. Joel Fernandes restructured the hooks
from irqs and preemption disabling and enabling. He got rid of a lot
of the preprocessor #ifdef mess that they caused.
He turned both lockdep and the latency tracers to use trace events
inserted in the preempt/irqs disabling paths. But unfortunately,
these started to cause issues in corner cases. Thus, parts of the
code was reverted back to where lockdep and the latency tracers just
get called directly (without using the trace events). But because the
original change cleaned up the code very nicely we kept that, as well
as the trace events for preempt and irqs disabling, but they are
limited to not being called in NMIs.
- Have trace events use SRCU for "rcu idle" calls. This was required
for the preempt/irqs off trace events. But it also had to not allow
them to be called in NMI context. Waiting till Paul makes an NMI safe
SRCU API.
- New notrace SRCU API to allow trace events to use SRCU.
- Addition of mcount-nop option support
- SPDX headers replacing GPL templates.
- Various other fixes and clean ups.
- Some fixes are marked for stable, but were not fully tested before
the merge window opened.
* tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
tracing: Fix SPDX format headers to use C++ style comments
tracing: Add SPDX License format tags to tracing files
tracing: Add SPDX License format to bpf_trace.c
blktrace: Add SPDX License format header
s390/ftrace: Add -mfentry and -mnop-mcount support
tracing: Add -mcount-nop option support
tracing: Avoid calling cc-option -mrecord-mcount for every Makefile
tracing: Handle CC_FLAGS_FTRACE more accurately
Uprobe: Additional argument arch_uprobe to uprobe_write_opcode()
Uprobes: Simplify uprobe_register() body
tracepoints: Free early tracepoints after RCU is initialized
uprobes: Use synchronize_rcu() not synchronize_sched()
tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister()
ftrace: Remove unused pointer ftrace_swapper_pid
tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing/irqsoff: Handle preempt_count for different configs
tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing: irqsoff: Account for additional preempt_disable
trace: Use rcu_dereference_raw for hooks from trace-event subsystem
tracing/kprobes: Fix within_notrace_func() to check only notrace functions
...
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Merge tag 'drm-next-2018-08-15' of git://anongit.freedesktop.org/drm/drm
Pull drm updates from Dave Airlie:
"This is the main drm pull request for 4.19.
Rob has some new hardware support for new qualcomm hw that I'll send
along separately. This has the display part of it, the remaining pull
is for the acceleration engine.
This also contains a wound-wait/wait-die mutex rework, Peter has acked
it for merging via my tree.
Otherwise mostly the usual level of activity. Summary:
core:
- Wound-wait/wait-die mutex rework
- Add writeback connector type
- Add "content type" property for HDMI
- Move GEM bo to drm_framebuffer
- Initial gpu scheduler documentation
- GPU scheduler fixes for dying processes
- Console deferred fbcon takeover support
- Displayport support for CEC tunneling over AUX
panel:
- otm8009a panel driver fixes
- Innolux TV123WAM and G070Y2-L01 panel driver
- Ilitek ILI9881c panel driver
- Rocktech RK070ER9427 LCD
- EDT ETM0700G0EDH6 and EDT ETM0700G0BDH6
- DLC DLC0700YZG-1
- BOE HV070WSA-100
- newhaven, nhd-4.3-480272ef-atxl LCD
- DataImage SCF0700C48GGU18
- Sharp LQ035Q7DB03
- p079zca: Refactor to support multiple panels
tinydrm:
- ILI9341 display panel
New driver:
- vkms - virtual kms driver to testing.
i915:
- Icelake:
Display enablement
DSI support
IRQ support
Powerwell support
- GPU reset fixes and improvements
- Full ppgtt support refactoring
- PSR fixes and improvements
- Execlist improvments
- GuC related fixes
amdgpu:
- Initial amdgpu documentation
- JPEG engine support on VCN
- CIK uses powerplay by default
- Move to using core PCIE functionality for gens/lanes
- DC/Powerplay interface rework
- Stutter mode support for RV
- Vega12 Powerplay updates
- GFXOFF fixes
- GPUVM fault debugging
- Vega12 GFXOFF
- DC improvements
- DC i2c/aux changes
- UVD 7.2 fixes
- Powerplay fixes for Polaris12, CZ/ST
- command submission bo_list fixes
amdkfd:
- Raven support
- Power management fixes
udl:
- Cleanups and fixes
nouveau:
- misc fixes and cleanups.
msm:
- DPU1 support display controller in sdm845
- GPU coredump support.
vmwgfx:
- Atomic modesetting validation fixes
- Support for multisample surfaces
armada:
- Atomic modesetting support completed.
exynos:
- IPPv2 fixes
- Move g2d to component framework
- Suspend/resume support cleanups
- Driver cleanups
imx:
- CSI configuration improvements
- Driver cleanups
- Use atomic suspend/resume helpers
- ipu-v3 V4L2 XRGB32/XBGR32 support
pl111:
- Add Nomadik LCDC variant
v3d:
- GPU scheduler jobs management
sun4i:
- R40 display engine support
- TCON TOP driver
mediatek:
- MT2712 SoC support
rockchip:
- vop fixes
omapdrm:
- Workaround for DRA7 errata i932
- Fix mm_list locking
mali-dp:
- Writeback implementation
PM improvements
- Internal error reporting debugfs
tilcdc:
- Single fix for deferred probing
hdlcd:
- Teardown fixes
tda998x:
- Converted to a bridge driver.
etnaviv:
- Misc fixes"
* tag 'drm-next-2018-08-15' of git://anongit.freedesktop.org/drm/drm: (1506 commits)
drm/amdgpu/sriov: give 8s for recover vram under RUNTIME
drm/scheduler: fix param documentation
drm/i2c: tda998x: correct PLL divider calculation
drm/i2c: tda998x: get rid of private fill_modes function
drm/i2c: tda998x: move mode_valid() to bridge
drm/i2c: tda998x: register bridge outside of component helper
drm/i2c: tda998x: cleanup from previous changes
drm/i2c: tda998x: allocate tda998x_priv inside tda998x_create()
drm/i2c: tda998x: convert to bridge driver
drm/scheduler: fix timeout worker setup for out of order job completions
drm/amd/display: display connected to dp-1 does not light up
drm/amd/display: update clk for various HDMI color depths
drm/amd/display: program display clock on cache match
drm/amd/display: Add NULL check for enabling dp ss
drm/amd/display: add vbios table check for enabling dp ss
drm/amd/display: Don't share clk source between DP and HDMI
drm/amd/display: Fix DP HBR2 Eye Diagram Pattern on Carrizo
drm/amd/display: Use calculated disp_clk_khz value for dce110
drm/amd/display: Implement custom degamma lut on dcn
drm/amd/display: Destroy aux_engines only once
...
Pull RCU updates from Thomas Gleixner:
"A large update to RCU:
Preparatory work for consolidating the RCU flavors:
- Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt,
and RCU-sched flavors, replacing the old ->gpnum and ->completed
pair of fields.
This change allows lockless code to obtain the complete
grace-period state with a single READ_ONCE(), which is needed to
maintain tolerable lock contention during the upcoming
consolidation of the three RCU flavors.
Note that grace-period sequence numbers are already used by
rcu_barrier(), expedited RCU grace periods, and SRCU, and are thus
already heavily used and well-tested. Joel Fernandes contributed a
number of excellent fixes and improvements.
- Clean up some grace-period-reporting loose ends, including
improving the handling of quiescent states from offline CPUs and
fixing some false-positive WARN_ON_ONCE() invocations.
(Strictly speaking, the WARN_ON_ONCE() invocations were quite
correct, but their invariants were (harmlessly) violated by the
earlier sloppy handling of quiescent states from offline CPUs.)
In addition, improve grace-period forward-progress guarantees so as
to allow removal of fail-safe checks that required otherwise
needless lock acquisitions. Finally, add more diagnostics to help
debug the upcoming consolidation of the RCU-bh, RCU-preempt, and
RCU-sched flavors.
The rest:
- SRCU updates
- Updates to rcutorture and associated scripting.
- The usual pile of miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (118 commits)
rcutorture: Fix rcu_barrier successes counter
rcutorture: Add support to detect if boost kthread prio is too low
rcutorture: Use monotonic timestamp for stall detection
rcutorture: Make boost test more robust
rcutorture: Disable RT throttling for boost tests
rcutorture: Emphasize testing of single reader protection type
rcutorture: Handle extended read-side critical sections
rcutorture: Make rcu_torture_timer() use rcu_torture_one_read()
rcutorture: Use per-CPU random state for rcu_torture_timer()
rcutorture: Use atomic increment for n_rcu_torture_timers
rcutorture: Extract common code from rcu_torture_reader()
rcuperf: Remove unused torturing_tasks() function
rcu: Remove rcutorture test version and sequence number
rcutorture: Change units of onoff_interval to jiffies
rcu: Assign higher prio to RCU threads if rcutorture is built-in
rculist: Improve documentation for list_for_each_entry_from_rcu()
srcu: Add grace-period number to rcutorture statistics printout
rcu: Print stall-warning NMI dyntick state in hexadecimal
MAINTAINERS: Update RCU, SRCU, and TORTURE-TEST entries
rcu: Make rcu_seq_diff() more exact
...
Joel Fernandes created a nice patch that cleaned up the duplicate hooks used
by lockdep and irqsoff latency tracer. It made both use tracepoints. But it
caused lockdep to trigger several false positives. We have not figured out
why yet, but removing lockdep from using the trace event hooks and just call
its helper functions directly (like it use to), makes the problem go away.
This is a partial revert of the clean up patch c3bc8fd637 ("tracing:
Centralize preemptirq tracepoints and unify their usage") that adds direct
calls for lockdep, but also keeps most of the clean up done to get rid of
the horrible preprocessor if statements.
Link: http://lkml.kernel.org/r/20180806155058.5ee875f4@gandalf.local.home
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Fixes: c3bc8fd637 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This patch detaches the preemptirq tracepoints from the tracers and
keeps it separate.
Advantages:
* Lockdep and irqsoff event can now run in parallel since they no longer
have their own calls.
* This unifies the usecase of adding hooks to an irqsoff and irqson
event, and a preemptoff and preempton event.
3 users of the events exist:
- Lockdep
- irqsoff and preemptoff tracers
- irqs and preempt trace events
The unification cleans up several ifdefs and makes the code in preempt
tracer and irqsoff tracers simpler. It gets rid of all the horrific
ifdeferry around PROVE_LOCKING and makes configuration of the different
users of the tracepoints more easy and understandable. It also gets rid
of the time_* function calls from the lockdep hooks used to call into
the preemptirq tracer which is not needed anymore. The negative delta in
lines of code in this patch is quite large too.
In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS
as a single point for registering probes onto the tracepoints. With
this,
the web of config options for preempt/irq toggle tracepoints and its
users becomes:
PREEMPT_TRACER PREEMPTIRQ_EVENTS IRQSOFF_TRACER PROVE_LOCKING
| | \ | |
\ (selects) / \ \ (selects) /
TRACE_PREEMPT_TOGGLE ----> TRACE_IRQFLAGS
\ /
\ (depends on) /
PREEMPTIRQ_TRACEPOINTS
Other than the performance tests mentioned in the previous patch, I also
ran the locking API test suite. I verified that all tests cases are
passing.
I also injected issues by not registering lockdep probes onto the
tracepoints and I see failures to confirm that the probes are indeed
working.
This series + lockdep probes not registered (just to inject errors):
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12:FAILED|FAILED| ok |
[ 0.000000] sirq-safe-A => hirqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
With this series + lockdep probes registered, all locking tests pass:
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
get_cpu_var disables preemption which has the potential to call into the
preemption disable trace points causing some complications. There's also
no need to disable preemption in uses of get_lock_stats anyway since
preempt is already disabled. So lets simplify the code.
Link: http://lkml.kernel.org/r/20180730222423.196630-2-joel@joelfernandes.org
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull RCU updates from Paul E. McKenney:
- An optimization and a fix for RCU expedited grace periods, with
the fix being from Boqun Feng.
- Miscellaneous fixes, including a lockdep-annotation fix from
Boqun Feng.
- SRCU updates.
- Updates to rcutorture and associated scripting.
- Introduce grace-period sequence numbers to the RCU-bh, RCU-preempt,
and RCU-sched flavors, replacing the old ->gpnum and ->completed
pair of fields. This change allows lockless code to obtain the
complete grace-period state with a single READ_ONCE(), which is
needed to maintain tolerable lock contention during the upcoming
consolidation of the three RCU flavors. Note that grace-period
sequence numbers are already used by rcu_barrier(), expedited
RCU grace periods, and SRCU, and are thus already heavily used
and well-tested. Joel Fernandes contributed a number of excellent
fixes and improvements.
- Clean up some grace-period-reporting loose ends, including
improving the handling of quiescent states from offline CPUs
and fixing some false-positive WARN_ON_ONCE() invocations.
(Strictly speaking, the WARN_ON_ONCE() invocations were quite
correct, but their invariants were (harmlessly) violated by the
earlier sloppy handling of quiescent states from offline CPUs.)
In addition, improve grace-period forward-progress guarantees so
as to allow removal of fail-safe checks that required otherwise
needless lock acquisitions. Finally, add more diagnostics to
help debug the upcoming consolidation of the RCU-bh, RCU-preempt,
and RCU-sched flavors.
- Additional miscellaneous fixes, including those contributed by
Byungchul Park, Mauro Carvalho Chehab, Joe Perches, Joel Fernandes,
Steven Rostedt, Andrea Parri, and Neil Brown.
- Additional torture-test changes, including several contributed by
Arnd Bergmann and Joel Fernandes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
