user/sven/linux.git/kernel/locking, branch v4.1.51

locking/lockdep: Add nest_lock integrity test

2017-11-06T04:54:30Z

[ Upstream commit 7fb4a2cea6b18dab56d609530d077f168169ed6b ] Boqun reported that hlock->references can overflow. Add a debug test for that to generate a clear error when this happens. Without this, lockdep is likely to report a mysterious failure on unlock. Reported-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Chris Wilson Cc: Linus Torvalds Cc: Nicolai Hähnle Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin

locktorture: Fix potential memory leak with rw lock test

2017-10-04T01:36:47Z

[ Upstream commit f4dbba591945dc301c302672adefba9e2ec08dc5 ] When running locktorture module with the below commands with kmemleak enabled: $ modprobe locktorture torture_type=rw_lock_irq $ rmmod locktorture The below kmemleak got caught: root@10:~# echo scan > /sys/kernel/debug/kmemleak [ 323.197029] kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak) root@10:~# cat /sys/kernel/debug/kmemleak unreferenced object 0xffffffc07592d500 (size 128): comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 c3 7b 02 00 00 00 00 00 .........{...... 00 00 00 00 00 00 00 00 d7 9b 02 00 00 00 00 00 ................ backtrace: [] create_object+0x110/0x288 [] kmemleak_alloc+0x58/0xa0 [] __kmalloc+0x234/0x318 [] 0xffffff80006fa130 [] do_one_initcall+0x44/0x138 [] do_init_module+0x68/0x1cc [] load_module+0x1a68/0x22e0 [] SyS_finit_module+0xe0/0xf0 [] el0_svc_naked+0x24/0x28 [] 0xffffffffffffffff unreferenced object 0xffffffc07592d480 (size 128): comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 3b 6f 01 00 00 00 00 00 ........;o...... 00 00 00 00 00 00 00 00 23 6a 01 00 00 00 00 00 ........#j...... backtrace: [] create_object+0x110/0x288 [] kmemleak_alloc+0x58/0xa0 [] __kmalloc+0x234/0x318 [] 0xffffff80006fa22c [] do_one_initcall+0x44/0x138 [] do_init_module+0x68/0x1cc [] load_module+0x1a68/0x22e0 [] SyS_finit_module+0xe0/0xf0 [] el0_svc_naked+0x24/0x28 [] 0xffffffffffffffff It is because cxt.lwsa and cxt.lrsa don't get freed in module_exit, so free them in lock_torture_cleanup() and free writer_tasks if reader_tasks is failed at memory allocation. Signed-off-by: Yang Shi Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett Signed-off-by: Sasha Levin

locking/ww_mutex: Report recursive ww_mutex locking early

2016-06-17T19:37:42Z

[ Upstream commit 0422e83d84ae24b933e4b0d4c1e0f0b4ae8a0a3b ] Recursive locking for ww_mutexes was originally conceived as an exception. However, it is heavily used by the DRM atomic modesetting code. Currently, the recursive deadlock is checked after we have queued up for a busy-spin and as we never release the lock, we spin until kicked, whereupon the deadlock is discovered and reported. A simple solution for the now common problem is to move the recursive deadlock discovery to the first action when taking the ww_mutex. Suggested-by: Maarten Lankhorst Signed-off-by: Chris Wilson Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Maarten Lankhorst Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1464293297-19777-1-git-send-email-chris@chris-wilson.co.uk Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin

lockdep: Fix a race between /proc/lock_stat and module unload

2015-06-07T13:46:30Z

The lock_class iteration of /proc/lock_stat is not serialized against the lockdep_free_key_range() call from module unload. Therefore it can happen that we find a class of which ->name/->key are no longer valid. There is a further bug in zap_class() that left ->name dangling. Cure this. Use RCU_INIT_POINTER() because NULL. Since lockdep_free_key_range() is rcu_sched serialized, we can read both ->name and ->key under rcu_read_lock_sched() (preempt-disable) and be assured that if we observe a !NULL value it stays safe to use for as long as we hold that lock. If we observe both NULL, skip the entry. Reported-by: Jerome Marchand Tested-by: Jerome Marchand Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20150602105013.GS3644@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

sched: Handle priority boosted tasks proper in setscheduler()

2015-05-08T09:53:55Z

Ronny reported that the following scenario is not handled correctly: T1 (prio = 10) lock(rtmutex); T2 (prio = 20) lock(rtmutex) boost T1 T1 (prio = 20) sys_set_scheduler(prio = 30) T1 prio = 30 .... sys_set_scheduler(prio = 10) T1 prio = 30 The last step is wrong as T1 should now be back at prio 20. Commit c365c292d059 ("sched: Consider pi boosting in setscheduler()") only handles the case where a boosted tasks tries to lower its priority. Fix it by taking the new effective priority into account for the decision whether a change of the priority is required. Reported-by: Ronny Meeus Tested-by: Steven Rostedt Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Steven Rostedt Cc: Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Mike Galbraith Fixes: c365c292d059 ("sched: Consider pi boosting in setscheduler()") Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505051806060.4225@nanos Signed-off-by: Ingo Molnar

lockdep: Make print_lock() robust against concurrent release

2015-04-17T07:42:14Z

During sysrq's show-held-locks command it is possible that hlock_class() returns NULL for a given lock. The result is then (after the warning): |BUG: unable to handle kernel NULL pointer dereference at 0000001c |IP: [] get_usage_chars+0x5/0x100 |Call Trace: | [] print_lock_name+0x23/0x60 | [] print_lock+0x5d/0x7e | [] lockdep_print_held_locks+0x74/0xe0 | [] debug_show_all_locks+0x132/0x1b0 | [] sysrq_handle_showlocks+0x8/0x10 This *might* happen because the thread on the other CPU drops the lock after we are looking ->lockdep_depth and ->held_locks points no longer to a lock that is held. The fix here is to simply ignore it and continue. Reported-by: Andreas Messerschmid Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Signed-off-by: Ingo Molnar

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-04-13T17:27:28Z

Pull core locking changes from Ingo Molnar: "Main changes: - jump label asm preparatory work for PowerPC (Anton Blanchard) - rwsem optimizations and cleanups (Davidlohr Bueso) - mutex optimizations and cleanups (Jason Low) - futex fix (Oleg Nesterov) - remove broken atomicity checks from {READ,WRITE}_ONCE() (Peter Zijlstra)" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: powerpc, jump_label: Include linux/jump_label.h to get HAVE_JUMP_LABEL define jump_label: Allow jump labels to be used in assembly jump_label: Allow asm/jump_label.h to be included in assembly locking/mutex: Further simplify mutex_spin_on_owner() locking: Remove atomicy checks from {READ,WRITE}_ONCE locking/rtmutex: Rename argument in the rt_mutex_adjust_prio_chain() documentation as well locking/rwsem: Fix lock optimistic spinning when owner is not running locking: Remove ACCESS_ONCE() usage locking/rwsem: Check for active lock before bailing on spinning locking/rwsem: Avoid deceiving lock spinners locking/rwsem: Set lock ownership ASAP locking/rwsem: Document barrier need when waking tasks locking/futex: Check PF_KTHREAD rather than !p->mm to filter out kthreads locking/mutex: Refactor mutex_spin_on_owner() locking/mutex: In mutex_spin_on_owner(), return true when owner changes

locking/mutex: Further simplify mutex_spin_on_owner()

2015-04-09T06:10:23Z

Similar to what Linus suggested for rwsem_spin_on_owner(), in mutex_spin_on_owner() instead of having while (true) and breaking out of the spin loop on lock->owner != owner, we can have the loop directly check for while (lock->owner == owner) to improve the readability of the code. It also shrinks the code a bit: text data bss dec hex filename 3721 0 0 3721 e89 mutex.o.before 3705 0 0 3705 e79 mutex.o.after Signed-off-by: Jason Low Cc: Andrew Morton Cc: Aswin Chandramouleeswaran Cc: Davidlohr Bueso Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tim Chen Link: http://lkml.kernel.org/r/1428521960-5268-2-git-send-email-jason.low2@hp.com [ Added code generation info. ] Signed-off-by: Ingo Molnar

locking/rtmutex: Rename argument in the rt_mutex_adjust_prio_chain() documentation as well

2015-03-25T12:43:55Z

The following commit changed "deadlock_detect" to "chwalk": 8930ed80f970 ("rtmutex: Cleanup deadlock detector debug logic") do that rename in the function's documentation as well. Signed-off-by: Tom(JeHyeon) Yeon Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1426655010-31651-1-git-send-email-tom.yeon@windriver.com Signed-off-by: Ingo Molnar

lockdep: Fix the module unload key range freeing logic

2015-03-23T09:49:07Z

Module unload calls lockdep_free_key_range(), which removes entries from the data structures. Most of the lockdep code OTOH assumes the data structures are append only; in specific see the comments in add_lock_to_list() and look_up_lock_class(). Clearly this has only worked by accident; make it work proper. The actual scenario to make it go boom would involve the memory freed by the module unlock being re-allocated and re-used for a lock inside of a rcu-sched grace period. This is a very unlikely scenario, still better plug the hole. Use RCU list iteration in all places and ammend the comments. Change lockdep_free_key_range() to issue a sync_sched() between removal from the lists and returning -- which results in the memory being freed. Further ensure the callers are placed correctly and comment the requirements. Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Andrey Tsyvarev Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Rusty Russell Cc: Thomas Gleixner Signed-off-by: Ingo Molnar