user/sven/linux.git/kernel/locking, branch v5.18.19

locking/lockdep: Fix lockdep_init_map_*() confusion

2022-08-17T12:40:30Z

[ Upstream commit eae6d58d67d9739be5f7ae2dbead1d0ef6528243 ] Commit dfd5e3f5fe27 ("locking/lockdep: Mark local_lock_t") added yet another lockdep_init_map_*() variant, but forgot to update all the existing users of the most complicated version. This could lead to a loss of lock_type and hence an incorrect report. Given the relative rarity of both local_lock and these annotations, this is unlikely to happen in practise, still, best fix things. Fixes: dfd5e3f5fe27 ("locking/lockdep: Mark local_lock_t") Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YqyEDtoan20K0CVD@worktop.programming.kicks-ass.net Signed-off-by: Sasha Levin

locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by first waiter

2022-08-03T10:05:29Z

commit 6eebd5fb20838f5971ba17df9f55cc4f84a31053 upstream. With commit d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent"), the writer that sets the handoff bit can be interrupted out without clearing the bit if the wait queue isn't empty. This disables reader and writer optimistic lock spinning and stealing. Now if a non-first writer in the queue is somehow woken up or a new waiter enters the slowpath, it can't acquire the lock. This is not the case before commit d257cc8cb8d5 as the writer that set the handoff bit will clear it when exiting out via the out_nolock path. This is less efficient as the busy rwsem stays in an unlock state for a longer time. In some cases, this new behavior may cause lockups as shown in [1] and [2]. This patch allows a non-first writer to ignore the handoff bit if it is not originally set or initiated by the first waiter. This patch is shown to be effective in fixing the lockup problem reported in [1]. [1] https://lore.kernel.org/lkml/20220617134325.GC30825@techsingularity.net/ [2] https://lore.kernel.org/lkml/3f02975c-1a9d-be20-32cf-f1d8e3dfafcc@oracle.com/ Fixes: d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent") Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Acked-by: John Donnelly Tested-by: Mel Gorman Link: https://lore.kernel.org/r/20220622200419.778799-1-longman@redhat.com Signed-off-by: Greg Kroah-Hartman

Merge tag 'locking-core-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-03-22T20:44:21Z

Pull locking updates from Ingo Molnar: "Changes in this cycle were: Bitops & cpumask: - Always inline various generic helpers, to improve code generation, but also for instrumentation, found by noinstr validation. - Add a x86-specific cpumask_clear_cpu() helper to improve code generation Atomics: - Fix atomic64_{read_acquire,set_release} fallbacks Lockdep: - Fix /proc/lockdep output loop iteration for classes - Fix /proc/lockdep potential access to invalid memory - Add Mark Rutland as reviewer for atomic primitives - Minor cleanups Jump labels: - Clean up the code a bit Misc: - Add __sched annotations to percpu rwsem primitives - Enable RT_MUTEXES on PREEMPT_RT by default - Stray v8086_mode() inlining fix, result of noinstr objtool validation" * tag 'locking-core-2022-03-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: jump_label: Refactor #ifdef of struct static_key jump_label: Avoid unneeded casts in STATIC_KEY_INIT_{TRUE,FALSE} locking/lockdep: Iterate lock_classes directly when reading lockdep files x86/ptrace: Always inline v8086_mode() for instrumentation cpumask: Add a x86-specific cpumask_clear_cpu() helper locking: Enable RT_MUTEXES by default on PREEMPT_RT. locking/local_lock: Make the empty local_lock_*() function a macro. atomics: Fix atomic64_{read_acquire,set_release} fallbacks locking: Add missing __sched attributes cpumask: Always inline helpers which use bit manipulation functions asm-generic/bitops: Always inline all bit manipulation helpers locking/lockdep: Avoid potential access of invalid memory in lock_class lockdep: Use memset_startat() helper in reinit_class() MAINTAINERS: add myself as reviewer for atomics

locking/lockdep: Iterate lock_classes directly when reading lockdep files

2022-02-16T14:57:58Z

When dumping lock_classes information via /proc/lockdep, we can't take the lockdep lock as the lock hold time is indeterminate. Iterating over all_lock_classes without holding lock can be dangerous as there is a slight chance that it may branch off to other lists leading to infinite loop or even access invalid memory if changes are made to all_lock_classes list in parallel. To avoid this problem, iteration of lock classes is now done directly on the lock_classes array itself. The lock_classes_in_use bitmap is checked to see if the lock class is being used. To avoid iterating the full array all the times, a new max_lock_class_idx value is added to track the maximum lock_class index that is currently being used. We can theoretically take the lockdep lock for iterating all_lock_classes when other lockdep files (lockdep_stats and lock_stat) are accessed as the lock hold time will be shorter for them. For consistency, they are also modified to iterate the lock_classes array directly. Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220211035526.1329503-2-longman@redhat.com

lockdep: Correct lock_classes index mapping

2022-02-11T22:30:02Z

A kernel exception was hit when trying to dump /proc/lockdep_chains after lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!": Unable to handle kernel paging request at virtual address 00054005450e05c3 ... 00054005450e05c3] address between user and kernel address ranges ... pc : [0xffffffece769b3a8] string+0x50/0x10c lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c ... Call trace: string+0x50/0x10c vsnprintf+0x468/0x69c seq_printf+0x8c/0xd8 print_name+0x64/0xf4 lc_show+0xb8/0x128 seq_read_iter+0x3cc/0x5fc proc_reg_read_iter+0xdc/0x1d4 The cause of the problem is the function lock_chain_get_class() will shift lock_classes index by 1, but the index don't need to be shifted anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range of class_idx in held_lock struct") already change the index to start from 0. The lock_classes[-1] located at chain_hlocks array. When printing lock_classes[-1] after the chain_hlocks entries are modified, the exception happened. The output of lockdep_chains are incorrect due to this problem too. Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey") Signed-off-by: Cheng Jui Wang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Boqun Feng Link: https://lore.kernel.org/r/20220210105011.21712-1-cheng-jui.wang@mediatek.com

locking: Add missing __sched attributes

2022-02-11T11:13:55Z

This patch adds __sched attributes to a few missing places to show blocked function rather than locking function in get_wchan. Signed-off-by: Minchan Kim Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220115231657.84828-1-minchan@kernel.org

locking/lockdep: Avoid potential access of invalid memory in lock_class

2022-01-25T21:30:28Z

It was found that reading /proc/lockdep after a lockdep splat may potentially cause an access to freed memory if lockdep_unregister_key() is called after the splat but before access to /proc/lockdep [1]. This is due to the fact that graph_lock() call in lockdep_unregister_key() fails after the clearing of debug_locks by the splat process. After lockdep_unregister_key() is called, the lock_name may be freed but the corresponding lock_class structure still have a reference to it. That invalid memory pointer will then be accessed when /proc/lockdep is read by a user and a use-after-free (UAF) error will be reported if KASAN is enabled. To fix this problem, lockdep_unregister_key() is now modified to always search for a matching key irrespective of the debug_locks state and zap the corresponding lock class if a matching one is found. [1] https://lore.kernel.org/lkml/77f05c15-81b6-bddd-9650-80d5f23fe330@i-love.sakura.ne.jp/ Fixes: 8b39adbee805 ("locking/lockdep: Make lockdep_unregister_key() honor 'debug_locks' again") Reported-by: Tetsuo Handa Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Bart Van Assche Link: https://lkml.kernel.org/r/20220103023558.1377055-1-longman@redhat.com

lockdep: Use memset_startat() helper in reinit_class()

2022-01-25T21:30:27Z

use memset_startat() helper to simplify the code, there is no functional change in this patch. Signed-off-by: Xiu Jianfeng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211213132618.105737-1-xiujianfeng@huawei.com

locking/rwlocks: introduce write_lock_nested

2022-01-22T06:33:37Z

In preparation for converting bit_spin_lock to rwlock in zsmalloc so that multiple writers of zspages can run at the same time but those zspages are supposed to be different zspage instance. Thus, it's not deadlock. This patch adds write_lock_nested to support the case for LOCKDEP. [minchan@kernel.org: fix write_lock_nested for RT] Link: https://lkml.kernel.org/r/YZfrMTAXV56HFWJY@google.com [bigeasy@linutronix.de: fixup write_lock_nested() implementation] Link: https://lkml.kernel.org/r/20211123170134.y6xb7pmpgdn4m3bn@linutronix.de Link: https://lkml.kernel.org/r/20211115185909.3949505-8-minchan@kernel.org Signed-off-by: Minchan Kim Signed-off-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Acked-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior Cc: Mike Galbraith Cc: Sergey Senozhatsky Cc: Thomas Gleixner Cc: Naresh Kamboju Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'locking_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-01-12T01:24:45Z

Pull locking updates from Borislav Petkov: "Lots of cleanups and preparation. Highlights: - futex: Cleanup and remove runtime futex_cmpxchg detection - rtmutex: Some fixes for the PREEMPT_RT locking infrastructure - kcsan: Share owner_on_cpu() between mutex,rtmutex and rwsem and annotate the racy owner->on_cpu access *once*. - atomic64: Dead-Code-Elemination" [ Description above by Peter Zijlstra ] * tag 'locking_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/atomic: atomic64: Remove unusable atomic ops futex: Fix additional regressions locking: Allow to include asm/spinlock_types.h from linux/spinlock_types_raw.h x86/mm: Include spinlock_t definition in pgtable. locking: Mark racy reads of owner->on_cpu locking: Make owner_on_cpu() into lockdep/selftests: Adapt ww-tests for PREEMPT_RT lockdep/selftests: Skip the softirq related tests on PREEMPT_RT lockdep/selftests: Unbalanced migrate_disable() & rcu_read_lock(). lockdep/selftests: Avoid using local_lock_{acquire|release}(). lockdep: Remove softirq accounting on PREEMPT_RT. locking/rtmutex: Add rt_mutex_lock_nest_lock() and rt_mutex_lock_killable(). locking/rtmutex: Squash self-deadlock check for ww_rt_mutex. locking: Remove rt_rwlock_is_contended(). sched: Trigger warning if ->migration_disabled counter underflows. futex: Fix sparc32/m68k/nds32 build regression futex: Remove futex_cmpxchg detection futex: Ensure futex_atomic_cmpxchg_inatomic() is present kernel/locking: Use a pointer in ww_mutex_trylock().