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2013-11-06locking: Move the lockdep code to kernel/locking/Peter Zijlstra1-4257/+0
Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-wl7s3tta5isufzfguc23et06@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-25rcu: Consistent rcu_is_watching() namingPaul E. McKenney1-2/+2
The old rcu_is_cpu_idle() function is just __rcu_is_watching() with preemption disabled. This commit therefore renames rcu_is_cpu_idle() to rcu_is_watching. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2013-05-12lockdep: remove task argument from debug_check_no_locks_heldColin Cross1-9/+8
The only existing caller to debug_check_no_locks_held calls it with 'current' as the task, and the freezer needs to call debug_check_no_locks_held but doesn't already have a current task pointer, so remove the argument. It is already assuming that the current task is relevant by dumping the current stack trace as part of the warning. This was originally part of 6aa9707099c (lockdep: check that no locks held at freeze time) which was reverted in dbf520a9d7d4. Original-author: Mandeep Singh Baines <msb@chromium.org> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-08Merge branch 'for-3.10/drivers' of git://git.kernel.dk/linux-blockLinus Torvalds1-0/+1
Pull block driver updates from Jens Axboe: "It might look big in volume, but when categorized, not a lot of drivers are touched. The pull request contains: - mtip32xx fixes from Micron. - A slew of drbd updates, this time in a nicer series. - bcache, a flash/ssd caching framework from Kent. - Fixes for cciss" * 'for-3.10/drivers' of git://git.kernel.dk/linux-block: (66 commits) bcache: Use bd_link_disk_holder() bcache: Allocator cleanup/fixes cciss: bug fix to prevent cciss from loading in kdump crash kernel cciss: add cciss_allow_hpsa module parameter drivers/block/mg_disk.c: add CONFIG_PM_SLEEP to suspend/resume functions mtip32xx: Workaround for unaligned writes bcache: Make sure blocksize isn't smaller than device blocksize bcache: Fix merge_bvec_fn usage for when it modifies the bvm bcache: Correctly check against BIO_MAX_PAGES bcache: Hack around stuff that clones up to bi_max_vecs bcache: Set ra_pages based on backing device's ra_pages bcache: Take data offset from the bdev superblock. mtip32xx: mtip32xx: Disable TRIM support mtip32xx: fix a smatch warning bcache: Disable broken btree fuzz tester bcache: Fix a format string overflow bcache: Fix a minor memory leak on device teardown bcache: Documentation updates bcache: Use WARN_ONCE() instead of __WARN() bcache: Add missing #include <linux/prefetch.h> ...
2013-04-26lockdep: Consolidate bug messages into a single print_lockdep_off() functionDave Jones1-15/+13
Also add some missing printk levels. Signed-off-by: Dave Jones <davej@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130425174002.GA26769@redhat.com [ Tweaked the messages a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-26lockdep: Print out additional debugging advice when we hit lockdep BUGsDave Jones1-0/+5
We occasionally get reports of these BUGs being hit, and the stack trace doesn't necessarily always tell us what we need to know about why we are hitting those limits. If users start attaching /proc/lock_stats to reports we may have more of a clue what's going on. Signed-off-by: Dave Jones <davej@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130423163403.GA12839@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08lockdep: Remove unnecessary 'hlock_next' variableHong Zhiguo1-4/+2
Signed-off-by: Hong Zhiguo <honkiko@gmail.com> Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1365058881-4044-1-git-send-email-honkiko@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-03-31Revert "lockdep: check that no locks held at freeze time"Paul Walmsley1-8/+9
This reverts commit 6aa9707099c4b25700940eb3d016f16c4434360d. Commit 6aa9707099c4 ("lockdep: check that no locks held at freeze time") causes problems with NFS root filesystems. The failures were noticed on OMAP2 and 3 boards during kernel init: [ BUG: swapper/0/1 still has locks held! ] 3.9.0-rc3-00344-ga937536 #1 Not tainted ------------------------------------- 1 lock held by swapper/0/1: #0: (&type->s_umount_key#13/1){+.+.+.}, at: [<c011e84c>] sget+0x248/0x574 stack backtrace: rpc_wait_bit_killable __wait_on_bit out_of_line_wait_on_bit __rpc_execute rpc_run_task rpc_call_sync nfs_proc_get_root nfs_get_root nfs_fs_mount_common nfs_try_mount nfs_fs_mount mount_fs vfs_kern_mount do_mount sys_mount do_mount_root mount_root prepare_namespace kernel_init_freeable kernel_init Although the rootfs mounts, the system is unstable. Here's a transcript from a PM test: http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt Here's what the test log should look like: http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt Mailing list discussion is here: http://lkml.org/lkml/2013/3/4/221 Deal with this for v3.9 by reverting the problem commit, until folks can figure out the right long-term course of action. Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: Jeff Layton <jlayton@redhat.com> Cc: Shawn Guo <shawn.guo@linaro.org> Cc: <maciej.rutecki@gmail.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ben Chan <benchan@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-24Export __lockdep_no_validate__Kent Overstreet1-0/+1
Hack, but bcache needs a way around lockdep for locking during garbage collection - we need to keep multiple btree nodes locked for coalescing and rw_lock_nested() isn't really sufficient or appropriate here. Signed-off-by: Kent Overstreet <koverstreet@google.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Ingo Molnar <mingo@redhat.com>
2013-02-28lockdep: check that no locks held at freeze timeMandeep Singh Baines1-9/+8
We shouldn't try_to_freeze if locks are held. Holding a lock can cause a deadlock if the lock is later acquired in the suspend or hibernate path (e.g. by dpm). Holding a lock can also cause a deadlock in the case of cgroup_freezer if a lock is held inside a frozen cgroup that is later acquired by a process outside that group. [akpm@linux-foundation.org: export debug_check_no_locks_held] Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ben Chan <benchan@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-19lockdep: Print more info when MAX_LOCK_DEPTH is exceededBen Greear1-1/+6
This helps debug cases where a lock is acquired over and over without being released. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ben Greear <greearb@candelatech.com> Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1360176979-4421-1-git-send-email-greearb@candelatech.com [ Changed the printout ordering. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-02-19lockdep: Rename print_unlock_inbalance_bug() to print_unlock_imbalance_bug()Srivatsa S. Bhat1-4/+4
Fix the typo in the function name (s/inbalance/imbalance) Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: rostedt@goodmis.org Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/20130108130547.32733.79507.stgit@srivatsabhat.in.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-09-13lockdep: Check if nested lock is actually heldMaarten Lankhorst1-0/+39
It is considered good form to lock the lock you claim to be nested in. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> [ removed nest_lock arg to print_lock_nested_lock_not_held in favour of hlock->nest_lock, also renamed the lock arg to hlock since its a held_lock type ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/5051A9E7.5040501@canonical.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-02-21lockdep: Add CPU-idle/offline warning to lockdep-RCU splatPaul E. McKenney1-1/+7
It is illegal to use RCU from a CPU that has reported idleness or offlinedness to RCU. However, it can be quite difficult to determine from a stack trace whether or not a given CPU is idle or offline. Therefore, this commit adds idle/offline diagnostics to the lockdep-RCU error message. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-01-06Merge branch 'perf-core-for-linus' of ↵Linus Torvalds1-17/+13
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (106 commits) perf kvm: Fix copy & paste error in description perf script: Kill script_spec__delete perf top: Fix a memory leak perf stat: Introduce get_ratio_color() helper perf session: Remove impossible condition check perf tools: Fix feature-bits rework fallout, remove unused variable perf script: Add generic perl handler to process events perf tools: Use for_each_set_bit() to iterate over feature flags perf tools: Unify handling of features when writing feature section perf report: Accept fifos as input file perf tools: Moving code in some files perf tools: Fix out-of-bound access to struct perf_session perf tools: Continue processing header on unknown features perf tools: Improve macros for struct feature_ops perf: builtin-record: Document and check that mmap_pages must be a power of two. perf: builtin-record: Provide advice if mmap'ing fails with EPERM. perf tools: Fix truncated annotation perf script: look up thread using tid instead of pid perf tools: Look up thread names for system wide profiling perf tools: Fix comm for processes with named threads ...
2012-01-06Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds1-0/+22
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) cpu: Export cpu_up() rcu: Apply ACCESS_ONCE() to rcu_boost() return value Revert "rcu: Permit rt_mutex_unlock() with irqs disabled" docs: Additional LWN links to RCU API rcu: Augment rcu_batch_end tracing for idle and callback state rcu: Add rcutorture tests for srcu_read_lock_raw() rcu: Make rcutorture test for hotpluggability before offlining CPUs driver-core/cpu: Expose hotpluggability to the rest of the kernel rcu: Remove redundant rcu_cpu_stall_suppress declaration rcu: Adaptive dyntick-idle preparation rcu: Keep invoking callbacks if CPU otherwise idle rcu: Irq nesting is always 0 on rcu_enter_idle_common rcu: Don't check irq nesting from rcu idle entry/exit rcu: Permit dyntick-idle with callbacks pending rcu: Document same-context read-side constraints rcu: Identify dyntick-idle CPUs on first force_quiescent_state() pass rcu: Remove dynticks false positives and RCU failures rcu: Reduce latency of rcu_prepare_for_idle() rcu: Eliminate RCU_FAST_NO_HZ grace-period hang rcu: Avoid needlessly IPIing CPUs at GP end ...
2011-12-20Merge commit 'v3.2-rc6' into perf/coreIngo Molnar1-1/+7
Merge reason: Update with the latest fixes. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-11rcu: Inform the user about extended quiescent state on PROVE_RCU warningFrederic Weisbecker1-0/+22
Inform the user if an RCU usage error is detected by lockdep while in an extended quiescent state (in this case, the RCU-free window in idle). This is accomplished by adding a line to the RCU lockdep splat indicating whether or not the splat occurred in extended quiescent state. Uses of RCU from within extended quiescent state mode are totally ignored by RCU, hence the importance of this diagnostic. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-12-06lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()Yong Zhang1-1/+7
Since commit f59de89 ("lockdep: Clear whole lockdep_map on initialization"), lockdep_init_map() will clear all the struct. But it will break lock_set_class()/lock_set_subclass(). A typical race condition is like below: CPU A CPU B lock_set_subclass(lockA); lock_set_class(lockA); lockdep_init_map(lockA); /* lockA->name is cleared */ memset(lockA); __lock_acquire(lockA); /* lockA->class_cache[] is cleared */ register_lock_class(lockA); look_up_lock_class(lockA); WARN_ON_ONCE(class->name != lock->name); lock->name = name; So restore to what we have done before commit f59de89 but annotate ->lock with kmemcheck_mark_initialized() to suppress the kmemcheck warning reported in commit f59de89. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reported-by: Borislav Petkov <bp@alien8.de> Suggested-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: <stable@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-06lockdep: Print lock name in lockdep_init_error()Ming Lei1-1/+4
This patch prints the name of the lock which is acquired before lockdep_init() is called, so that users can easily find which lock triggered the lockdep init error warning. This patch also removes the lockdep_init_error() message of "Arch code didn't call lockdep_init() early enough?" since lockdep_init() is called in arch independent code now. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321508072-23853-2-git-send-email-tom.leiming@gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-06lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()Yong Zhang1-1/+7
Since commit f59de89 ("lockdep: Clear whole lockdep_map on initialization"), lockdep_init_map() will clear all the struct. But it will break lock_set_class()/lock_set_subclass(). A typical race condition is like below: CPU A CPU B lock_set_subclass(lockA); lock_set_class(lockA); lockdep_init_map(lockA); /* lockA->name is cleared */ memset(lockA); __lock_acquire(lockA); /* lockA->class_cache[] is cleared */ register_lock_class(lockA); look_up_lock_class(lockA); WARN_ON_ONCE(class->name != lock->name); lock->name = name; So restore to what we have done before commit f59de89 but annotate ->lock with kmemcheck_mark_initialized() to suppress the kmemcheck warning reported in commit f59de89. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reported-by: Borislav Petkov <bp@alien8.de> Suggested-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-06lockdep, rtmutex, bug: Show taint flags on errorBen Hutchings1-8/+15
Show the taint flags in all lockdep and rtmutex-debug error messages. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1319773015.6759.30.camel@deadeye Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-14lockdep: Always try to set ->class_cache in register_lock_class() ↵Yong Zhang1-1/+2
lockdep_init_map() Commit ["62016250 lockdep: Add improved subclass caching"] tries to improve performance (expecially to reduce the cost of rq->lock) when using lockdep, but it fails due to lockdep_init_map() in which ->class_cache is cleared. The typical caller is lock_set_subclass(), after that class will not be cached anymore. This patch tries to achive the goal of commit 62016250 by always setting ->class_cache in register_lock_class(). === Score comparison of benchmarks === for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done before: min: 0.604, max: 0.660, avg: 0.622 after: min: 0.414, max: 0.473, avg: 0.427 for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done before: min: 2.347, max: 2.421, avg: 2.391 after: min: 1.652, max: 1.699, avg: 1.671 Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20111109080714.GC8124@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-11Merge branch 'tip/perf/core' of ↵Ingo Molnar1-17/+13
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
2011-11-07lockdep: Show subclass in pretty print of lockdep outputSteven Rostedt1-17/+13
The pretty print of the lockdep debug splat uses just the lock name to show how the locking scenario happens. But when it comes to nesting locks, the output becomes confusing which takes away the point of the pretty printing of the lock scenario. Without displaying the subclass info, we get the following output: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slock-AF_INET); lock(slock-AF_INET); lock(slock-AF_INET); lock(slock-AF_INET); *** DEADLOCK *** The above looks more of a A->A locking bug than a A->B B->A. By adding the subclass to the output, we can see what really happened: other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slock-AF_INET); lock(slock-AF_INET/1); lock(slock-AF_INET); lock(slock-AF_INET/1); *** DEADLOCK *** This bug was discovered while tracking down a real bug caught by lockdep. Link: http://lkml.kernel.org/r/20111025202049.GB25043@hostway.ca Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Simon Kirby <sim@hostway.ca> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-10-26Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds1-37/+47
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits) rcu: Move propagation of ->completed from rcu_start_gp() to rcu_report_qs_rsp() rcu: Remove rcu_needs_cpu_flush() to avoid false quiescent states rcu: Wire up RCU_BOOST_PRIO for rcutree rcu: Make rcu_torture_boost() exit loops at end of test rcu: Make rcu_torture_fqs() exit loops at end of test rcu: Permit rt_mutex_unlock() with irqs disabled rcu: Avoid having just-onlined CPU resched itself when RCU is idle rcu: Suppress NMI backtraces when stall ends before dump rcu: Prohibit grace periods during early boot rcu: Simplify unboosting checks rcu: Prevent early boot set_need_resched() from __rcu_pending() rcu: Dump local stack if cannot dump all CPUs' stacks rcu: Move __rcu_read_unlock()'s barrier() within if-statement rcu: Improve rcu_assign_pointer() and RCU_INIT_POINTER() documentation rcu: Make rcu_assign_pointer() unconditionally insert a memory barrier rcu: Make rcu_implicit_dynticks_qs() locals be correct size rcu: Eliminate in_irq() checks in rcu_enter_nohz() nohz: Remove nohz_cpu_mask rcu: Document interpretation of RCU-lockdep splats rcu: Allow rcutorture's stat_interval parameter to be changed at runtime ...
2011-09-29rcu: Restore checks for blocking in RCU read-side critical sectionsPaul E. McKenney1-37/+47
Long ago, using TREE_RCU with PREEMPT would result in "scheduling while atomic" diagnostics if you blocked in an RCU read-side critical section. However, PREEMPT now implies TREE_PREEMPT_RCU, which defeats this diagnostic. This commit therefore adds a replacement diagnostic based on PROVE_RCU. Because rcu_lockdep_assert() and lockdep_rcu_dereference() are now being used for things that have nothing to do with rcu_dereference(), rename lockdep_rcu_dereference() to lockdep_rcu_suspicious() and add a third argument that is a string indicating what is suspicious. This third argument is passed in from a new third argument to rcu_lockdep_assert(). Update all calls to rcu_lockdep_assert() to add an informative third argument. Also, add a pair of rcu_lockdep_assert() calls from within rcu_note_context_switch(), one complaining if a context switch occurs in an RCU-bh read-side critical section and another complaining if a context switch occurs in an RCU-sched read-side critical section. These are present only if the PROVE_RCU kernel parameter is enabled. Finally, fix some checkpatch whitespace complaints in lockdep.c. Again, you must enable PROVE_RCU to see these new diagnostics. But you are enabling PROVE_RCU to check out new RCU uses in any case, aren't you? Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-09-18lockdep: Comment all warningsPeter Zijlstra1-9/+147
Andrew requested I comment all the lockdep WARN()s to help other people figure out wth is wrong.. Requested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1315301493.3191.9.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-09lockdep: Fix wrong assumption in match_held_lockPeter Zijlstra1-1/+7
match_held_lock() was assuming it was being called on a lock class that had already seen usage. This condition was true for bug-free code using lockdep_assert_held(), since you're in fact holding the lock when calling it. However the assumption fails the moment you assume the assertion can fail, which is the whole point of having the assertion in the first place. Anyway, now that there's more lockdep_is_held() users, notably __rcu_dereference_check(), its much easier to trigger this since we test for a number of locks and we only need to hold any one of them to be good. Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1312547787.28695.2.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-04lockdep: Clear whole lockdep_map on initializationTejun Heo1-4/+1
lockdep_init_map() only initializes parts of lockdep_map and triggers kmemcheck warning when it is copied as a whole. There isn't anything to be gained by clearing selectively. memset() the whole structure and remove loop for ->class_cache[] clearing. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=35532 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Christian Casteyde <casteyde.christian@free.fr> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=35532 Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110714131909.GJ3455@htj.dyndns.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-04lockdep: Fix up warningPeter Zijlstra1-1/+1
On Sun, 2011-07-24 at 21:06 -0400, Arnaud Lacombe wrote: > /src/linux/linux/kernel/lockdep.c: In function 'mark_held_locks': > /src/linux/linux/kernel/lockdep.c:2471:31: warning: comparison of > distinct pointer types lacks a cast The warning is harmless in this case, but the below makes it go away. Reported-by: Arnaud Lacombe <lacombar@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1311588599.2617.56.camel@laptop Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-04lockdep: Fix trace_hardirqs_on_caller()Peter Zijlstra1-14/+16
Commit dd4e5d3ac4a ("lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion") made a bit of a mess of the various checks and error conditions. In particular it moved the check for !irqs_disabled() before the spurious enable test, resulting in some warnings. Reported-by: Arnaud Lacombe <lacombar@gmail.com> Reported-by: Dave Jones <davej@redhat.com> Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1311679697.24752.28.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-23Merge branch 'core-printk-for-linus' of ↵Linus Torvalds1-10/+20
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion printk: Fix console_sem vs logbuf_lock unlock race printk: Release console_sem after logbuf_lock
2011-07-21lockdep: Fix lockdep_no_validate against IRQ statesPeter Zijlstra1-0/+3
Thomas noticed that a lock marked with lockdep_set_novalidate_class() will still trigger warnings for IRQ inversions. Cure this by skipping those when marking irq state. Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-2dp5vmpsxeraqm42kgww6ge2@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-22lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursionPeter Zijlstra1-10/+20
Commit: 1efc5da3cf56: [PATCH] order of lockdep off/on in vprintk() should be changed explains the reason for having raw_local_irq_*() and lockdep_off() in printk(). Instead of working around the broken recursion detection of interrupt state tracking, fix it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: efault@gmx.de Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110621153806.185242734@chello.nl Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-07lockdep: Fix lock_is_held() on recursionPeter Zijlstra1-1/+1
The main lock_is_held() user is lockdep_assert_held(), avoid false assertions in lockdep_off() sections by unconditionally reporting the lock is taken. [ the reason this is important is a lockdep_assert_held() in ttwu() which triggers a warning under lockdep_off() as in printk() which can trigger another wakeup and lock up due to spinlock recursion, as reported and heroically debugged by Arne Jansen ] Reported-and-tested-by: Arne Jansen <lists@die-jansens.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@kernel.org> Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Remove cmpxchg to update nr_chain_hlocksSteven Rostedt1-10/+4
For some reason nr_chain_hlocks is updated with cmpxchg, but this is performed inside of the lockdep global "grab_lock()", which also makes simple modification of this variable atomic. Remove the cmpxchg logic for updating nr_chain_hlocks and simplify the code. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014300.727863282@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Print a nicer description for simple irq lock inversionsSteven Rostedt1-0/+20
Lockdep output can be pretty cryptic, having nicer output can save a lot of head scratching. When a simple irq inversion scenario is detected by lockdep (lock A taken in interrupt context but also in thread context without disabling interrupts) we now get the following (hopefully more informative) output: other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(lockA); <Interrupt> lock(lockA); *** DEADLOCK *** Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014300.436140880@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Replace "Bad BFS generated tree" message with something less crypticSteven Rostedt1-1/+1
The message of "Bad BFS generated tree" is a bit confusing. Replace it with a more sane error message. Thanks to Peter Zijlstra for helping me come up with a better message. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014300.135521252@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Print a nicer description for irq inversion bugsSteven Rostedt1-5/+29
Irq inversion and irq dependency bugs are only subtly different. The diffenerence lies where the interrupt occurred. For irq dependency: irq_disable lock(A) lock(B) unlock(B) unlock(A) irq_enable lock(B) unlock(B) <interrupt> lock(A) The interrupt comes in after it has been established that lock A can be held when taking an irq unsafe lock. Lockdep detects the problem when taking lock A in interrupt context. With the irq_inversion the irq happens before it is established and lockdep detects the problem with the taking of lock B: <interrupt> lock(A) irq_disable lock(A) lock(B) unlock(B) unlock(A) irq_enable lock(B) unlock(B) Since the problem with the locking logic for both of these issues is in actuality the same, they both should report the same scenario. This patch implements that and prints this: other info that might help us debug this: Chain exists of: &rq->lock --> lockA --> lockC Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(lockC); local_irq_disable(); lock(&rq->lock); lock(lockA); <Interrupt> lock(&rq->lock); *** DEADLOCK *** Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014259.910720381@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Print a nicer description for simple deadlocksSteven Rostedt1-0/+21
Lockdep output can be pretty cryptic, having nicer output can save a lot of head scratching. When a simple deadlock scenario is detected by lockdep (lock A -> lock A) we now get the following new output: other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(lock)->rlock); lock(&(lock)->rlock); *** DEADLOCK *** Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014259.643930104@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Print a nicer description for normal deadlocksSteven Rostedt1-0/+55
The lockdep output can be pretty cryptic, having nicer output can save a lot of head scratching. When a normal deadlock scenario is detected by lockdep (lock A -> lock B and there exists a place where lock B -> lock A) we now get the following new output: other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(lockB); lock(lockA); lock(lockB); lock(lockA); *** DEADLOCK *** On cases where there's a deeper chair, it shows the partial chain that can cause the issue: Chain exists of: lockC --> lockA --> lockB Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(lockB); lock(lockA); lock(lockB); lock(lockC); *** DEADLOCK *** Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014259.380621789@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-22lockdep: Print a nicer description for irq lock inversionsSteven Rostedt1-0/+70
Locking order inversion due to interrupts is a subtle problem. When an irq lockiinversion discovered by lockdep it currently reports something like: [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ] ... and then prints out the locks that are involved, as back traces. Judging by lkml feedback developers were routinely confused by what a HARDIRQ->safe to unsafe issue is all about, and sometimes even blew it off as a bug in lockdep. It is not obvious when lockdep prints this message about a lock that is never taken in interrupt context. After explaining the problems that lockdep is reporting, I decided to add a description of the problem in visual form. Now the following is shown: --- other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(lockA); local_irq_disable(); lock(&rq->lock); lock(lockA); <Interrupt> lock(&rq->lock); *** DEADLOCK *** --- The above is the case when the unsafe lock is taken while holding a lock taken in irq context. But when a lock is taken that also grabs a unsafe lock, the call chain is shown: --- other info that might help us debug this: Chain exists of: &rq->lock --> lockA --> lockC Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(lockC); local_irq_disable(); lock(&rq->lock); lock(lockA); <Interrupt> lock(&rq->lock); *** DEADLOCK *** Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110421014259.132728798@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-03-31Fix common misspellingsLucas De Marchi1-2/+2
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-01-20lockdep: Move early boot local IRQ enable/disable status to init/main.cTejun Heo1-17/+1
During early boot, local IRQ is disabled until IRQ subsystem is properly initialized. During this time, no one should enable local IRQ and some operations which usually are not allowed with IRQ disabled, e.g. operations which might sleep or require communications with other processors, are allowed. lockdep tracked this with early_boot_irqs_off/on() callbacks. As other subsystems need this information too, move it to init/main.c and make it generally available. While at it, toggle the boolean to early_boot_irqs_disabled instead of enabled so that it can be initialized with %false and %true indicates the exceptional condition. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <20110120110635.GB6036@htj.dyndns.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-18lockdep: Check the depth of subclassHitoshi Mitake1-8/+10
Current look_up_lock_class() doesn't check the parameter "subclass". This rarely rises problems because the main caller of this function, register_lock_class(), checks it. But register_lock_class() is not the only function which calls look_up_lock_class(). lock_set_class() and its callees also call it. And lock_set_class() doesn't check this parameter. This will rise problems when the the value of subclass is larger than MAX_LOCKDEP_SUBCLASSES. Because the address (used as the key of class) caliculated with too large subclass has a probability to point another key in different lock_class_key. Of course this problem depends on the memory layout and occurs with really low probability. Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> Cc: Dmitry Torokhov <dtor@mail.ru> Cc: Vojtech Pavlik <vojtech@ucw.cz> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286958626-986-1-git-send-email-mitake@dcl.info.waseda.ac.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-18lockdep: Add improved subclass cachingHitoshi Mitake1-7/+18
Current lockdep_map only caches one class with subclass == 0, and looks up hash table of classes when subclass != 0. It seems that this has no problem because the case of subclass != 0 is rare. But locks of struct rq are acquired with subclass == 1 when task migration is executed. Task migration is high frequent event, so I modified lockdep to cache subclasses. I measured the score of perf bench sched messaging. This patch has slightly but certain (order of milli seconds or 10 milli seconds) effect when lots of tasks are running. I'll show the result in the tail of this description. NR_LOCKDEP_CACHING_CLASSES specifies how many classes can be cached in the instances of lockdep_map. I discussed with Peter Zijlstra in LinuxCon Japan about this approach and he taught me that caching every subclasses(8) is cleary waste of memory. So number of cached classes should be configurable. === Score comparison of benchmarks === # "min" means best score, and "max" means worst score for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done before: min: 0.565000, max: 0.583000, avg: 0.572500 after: min: 0.559000, max: 0.568000, avg: 0.563300 # with more processes for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done before: min: 2.274000, max: 2.298000, avg: 2.286300 after: min: 2.242000, max: 2.270000, avg: 2.259700 Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286269311-28336-2-git-send-email-mitake@dcl.info.waseda.ac.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-08-17lockdep: Remove __debug_show_held_locksJohn Kacur1-7/+1
There is no longer any functional difference between __debug_show_held_locks() and debug_show_held_locks(), so remove the former. Signed-off-by: John Kacur <jkacur@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1281021054-4228-1-git-send-email-jkacur@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-06-09sched_clock: Add local_clock() API and improve documentationPeter Zijlstra1-1/+1
For people who otherwise get to write: cpu_clock(smp_processor_id()), there is now: local_clock(). Also, as per suggestion from Andrew, provide some documentation on the various clock interfaces, and minimize the unsigned long long vs u64 mess. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jens Axboe <jaxboe@fusionio.com> LKML-Reference: <1275052414.1645.52.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-05-21lockdep: Add novalidate class for dev->mutex conversionPeter Zijlstra1-0/+5
The conversion of device->sem to device->mutex resulted in lockdep warnings. Create a novalidate class for now until the driver folks come up with separate classes. That way we have at least the basic mutex debugging coverage. Add a checkpatch error so the usage is reserved for device->mutex. [ tglx: checkpatch and compile fix for LOCKDEP=n ] Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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