09 Mar, 2019
2 commits
-
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Dave Hansen
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Thomas Gleixner
Cc: Will Deacon
Cc: longman@redhat.com
Link: https://lkml.kernel.org/r/c20aa0f0-42ab-a884-d931-7d4ec2bf0cdc@acm.org
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Alexander Shishkin
Cc: Andrew Morton
Cc: Andy Lutomirski
Cc: Arnaldo Carvalho de Melo
Cc: Bart Van Assche
Cc: Borislav Petkov
Cc: Dave Hansen
Cc: Frederic Weisbecker
Cc: H. Peter Anvin
Cc: Jiri Olsa
Cc: Joel Fernandes (Google)
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stephane Eranian
Cc: Steven Rostedt (VMware)
Cc: Tetsuo Handa
Cc: Thomas Gleixner
Cc: Vince Weaver
Cc: Waiman Long
Cc: Will Deacon
Link: https://lkml.kernel.org/r/20190307075222.3424524-1-arnd@arndb.de
Signed-off-by: Ingo Molnar
06 Mar, 2019
2 commits
-
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
...
28 Feb, 2019
21 commits
-
Signed-off-by: Ingo Molnar
-
And move the whole lot under CONFIG_DEBUG_LOCKDEP.
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Will Deacon
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
Signed-off-by: Bart Van Assche
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Link: https://lkml.kernel.org/r/20190214230058.196511-18-bvanassche@acm.org
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
Reflect that add_chain_cache() is always called with the graph lock held.
Signed-off-by: Bart Van Assche
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
This patch does not change any functionality but makes the next patch in
this series easier to read.Signed-off-by: Bart Van Assche
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
synchronize_sched() has been removed recently. Update the comments that
refer to synchronize_sched().Signed-off-by: Bart Van Assche
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
Cc: johannes.berg@intel.com
Cc: tj@kernel.org
Fixes: 51959d85f32d ("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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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:ca58abcb4a6d ("lockdep: sanitise CONFIG_PROVE_LOCKING")
Include the size of the chain_hlocks[] array.
Signed-off-by: Bart Van Assche
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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:
a63f38cc4ccf ("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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Johannes Berg
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
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 -
With the > 4 nesting levels case handled by the commit:
d682b596d993 ("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
Signed-off-by: Peter Zijlstra (Intel)
Acked-by: Will Deacon
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: https://lkml.kernel.org/r/1551057253-3231-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar -
Signed-off-by: Ingo Molnar
13 Feb, 2019
2 commits
-
…/linux-rcu into core/rcu
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/includeSigned-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
Cc: Alexander Shishkin
Cc: Andrea Righi
Cc: Arnaldo Carvalho de Melo
Cc: Jiri Olsa
Cc: Linus Torvalds
Cc: Mathieu Desnoyers
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/154998810578.31052.1680977921449292812.stgit@devbox
Signed-off-by: Ingo Molnar
10 Feb, 2019
2 commits
-
…2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD
doc.2019.01.26a: Documentation updates.
fixes.2019.01.26a: Miscellaneous fixes.
sil.2019.01.26a: Removal of a few more spin_is_locked() instances.
spdx.2019.02.09a: Add SPDX identifiers to RCU files
srcu.2019.01.26a: SRCU updates.
torture.2019.01.26a: Torture-test updates. -
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.Signed-off-by: Paul E. McKenney
Reviewed-by: Thomas Gleixner
08 Feb, 2019
1 commit
-
commit 56222b212e8e ("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
--> WARNlock(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: 56222b212e8e ("futex: Drop hb->lock before enqueueing on the rtmutex")
Reported-by: Heiko Carstens
Co-developed-by: Peter Zijlstra
Signed-off-by: Peter Zijlstra
Signed-off-by: Thomas Gleixner
Tested-by: Heiko Carstens
Cc: Martin Schwidefsky
Cc: linux-s390@vger.kernel.org
Cc: Stefan Liebler
Cc: Sebastian Sewior
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1901292311410.1950@nanos.tec.linutronix.de
04 Feb, 2019
4 commits
-
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: H. Peter Anvin
Cc: James Morse
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: SRINIVAS
Cc: Thomas Gleixner
Cc: Will Deacon
Cc: Zhenzhong Duan
Link: https://lkml.kernel.org/r/1548798828-16156-3-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Acked-by: Will Deacon
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: H. Peter Anvin
Cc: James Morse
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: SRINIVAS
Cc: Thomas Gleixner
Cc: Zhenzhong Duan
Link: https://lkml.kernel.org/r/1548798828-16156-2-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Waiman Long
Cc: Will Deacon
Cc: Xie Yongji
Cc: Yongji Xie
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 -
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
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Will Deacon
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar
26 Jan, 2019
1 commit
-
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
Signed-off-by: Paul E. McKenney
21 Jan, 2019
4 commits
-
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 writeWe can even remove some comments that were compensating for the lack of
those constant names.Signed-off-by: Frederic Weisbecker
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Will Deacon
Link: https://lkml.kernel.org/r/1545973321-24422-3-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar -
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
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Will Deacon
Link: https://lkml.kernel.org/r/1545973321-24422-2-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar -
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
Reported-by: Tetsuo Handa
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: Will Deacon
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar -
Because wake_q_add() can imply an immediate wakeup (cmpxchg failure
case), we must not rely on the wakeup being delayed. However, commit:e38513905eea ("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
Signed-off-by: Zhang Yu
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Fixes: e38513905eea ("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
05 Jan, 2019
1 commit
-
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
Reviewed-by: Andrew Morton
Cc: Peter Zijlstra
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds