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* Merge tag 'rcu.2023.02.10a' of ↵Linus Torvalds2023-02-211-43/+58
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull RCU updates from Paul McKenney: - Documentation updates - Miscellaneous fixes, perhaps most notably: - Throttling callback invocation based on the number of callbacks that are now ready to invoke instead of on the total number of callbacks - Several patches that suppress false-positive boot-time diagnostics, for example, due to lockdep not yet being initialized - Make expedited RCU CPU stall warnings dump stacks of any tasks that are blocking the stalled grace period. (Normal RCU CPU stall warnings have done this for many years) - Lazy-callback fixes to avoid delays during boot, suspend, and resume. (Note that lazy callbacks must be explicitly enabled, so this should not (yet) affect production use cases) - Make kfree_rcu() and friends take advantage of polled grace periods, thus reducing memory footprint by almost two orders of magnitude, admittedly on a microbenchmark This also begins the transition from kfree_rcu(p) to kfree_rcu_mightsleep(p). This transition was motivated by bugs where kfree_rcu(p), which can block, was typed instead of the intended kfree_rcu(p, rh) - SRCU updates, perhaps most notably fixing a bug that causes SRCU to fail when booted on a system with a non-zero boot CPU. This surprising situation actually happens for kdump kernels on the powerpc architecture This also adds an srcu_down_read() and srcu_up_read(), which act like srcu_read_lock() and srcu_read_unlock(), but allow an SRCU read-side critical section to be handed off from one task to another - Clean up the now-useless SRCU Kconfig option There are a few more commits that are not yet acked or pulled into maintainer trees, and these will be in a pull request for a later merge window - RCU-tasks updates, perhaps most notably these fixes: - A strange interaction between PID-namespace unshare and the RCU-tasks grace period that results in a low-probability but very real hang - A race between an RCU tasks rude grace period on a single-CPU system and CPU-hotplug addition of the second CPU that can result in a too-short grace period - A race between shrinking RCU tasks down to a single callback list and queuing a new callback to some other CPU, but where that queuing is delayed for more than an RCU grace period. This can result in that callback being stranded on the non-boot CPU - Torture-test updates and fixes - Torture-test scripting updates and fixes - Provide additional RCU CPU stall-warning information in kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y, and restore the full five-minute timeout limit for expedited RCU CPU stall warnings * tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (80 commits) rcu/kvfree: Add kvfree_rcu_mightsleep() and kfree_rcu_mightsleep() kernel/notifier: Remove CONFIG_SRCU init: Remove "select SRCU" fs/quota: Remove "select SRCU" fs/notify: Remove "select SRCU" fs/btrfs: Remove "select SRCU" fs: Remove CONFIG_SRCU drivers/pci/controller: Remove "select SRCU" drivers/net: Remove "select SRCU" drivers/md: Remove "select SRCU" drivers/hwtracing/stm: Remove "select SRCU" drivers/dax: Remove "select SRCU" drivers/base: Remove CONFIG_SRCU rcu: Disable laziness if lazy-tracking says so rcu: Track laziness during boot and suspend rcu: Remove redundant call to rcu_boost_kthread_setaffinity() rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts rcu: Align the output of RCU CPU stall warning messages rcu: Add RCU stall diagnosis information sched: Add helper nr_context_switches_cpu() ...
| * locktorture: Make the rt_boost factor a tunableJoel Fernandes (Google)2023-01-051-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rt boosting in locktorture has a factor variable s currently large enough that boosting only happens once every minute or so. Add a tunable to reduce the factor so that boosting happens more often, to test paths and arrive at failure modes earlier. With this change, I can set the factor to like 50 and have the boosting happens every 10 seconds or so. Tested with boot parameters: locktorture.torture_type=mutex_lock locktorture.onoff_interval=1 locktorture.nwriters_stress=8 locktorture.stutter=0 locktorture.rt_boost=1 locktorture.rt_boost_factor=50 locktorture.nlocks=3 Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| * locktorture: Allow non-rtmutex lock types to be boostedJoel Fernandes (Google)2023-01-051-43/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently RT boosting is only done for rtmutex_lock, however with proxy execution, we also have the mutex_lock participating in priorities. To exercise the testing better, add RT boosting to other lock testing types as well, using a new knob (rt_boost). Tested with boot parameters: locktorture.torture_type=mutex_lock locktorture.onoff_interval=1 locktorture.nwriters_stress=8 locktorture.stutter=0 locktorture.rt_boost=1 locktorture.rt_boost_factor=1 locktorture.nlocks=3 Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | Merge tag 'sched-core-2023-02-20' of ↵Linus Torvalds2023-02-201-0/+3
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - Improve the scalability of the CFS bandwidth unthrottling logic with large number of CPUs. - Fix & rework various cpuidle routines, simplify interaction with the generic scheduler code. Add __cpuidle methods as noinstr to objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks. - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query previously issued registrations. - Limit scheduler slice duration to the sysctl_sched_latency period, to improve scheduling granularity with a large number of SCHED_IDLE tasks. - Debuggability enhancement on sys_exit(): warn about disabled IRQs, but also enable them to prevent a cascade of followup problems and repeat warnings. - Fix the rescheduling logic in prio_changed_dl(). - Micro-optimize cpufreq and sched-util methods. - Micro-optimize ttwu_runnable() - Micro-optimize the idle-scanning in update_numa_stats(), select_idle_capacity() and steal_cookie_task(). - Update the RSEQ code & self-tests - Constify various scheduler methods - Remove unused methods - Refine __init tags - Documentation updates - Misc other cleanups, fixes * tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits) sched/rt: pick_next_rt_entity(): check list_entry sched/deadline: Add more reschedule cases to prio_changed_dl() sched/fair: sanitize vruntime of entity being placed sched/fair: Remove capacity inversion detection sched/fair: unlink misfit task from cpu overutilized objtool: mem*() are not uaccess safe cpuidle: Fix poll_idle() noinstr annotation sched/clock: Make local_clock() noinstr sched/clock/x86: Mark sched_clock() noinstr x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read() x86/atomics: Always inline arch_atomic64*() cpuidle: tracing, preempt: Squash _rcuidle tracing cpuidle: tracing: Warn about !rcu_is_watching() cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG cpuidle: drivers: firmware: psci: Dont instrument suspend code KVM: selftests: Fix build of rseq test exit: Detect and fix irq disabled state in oops cpuidle, arm64: Fix the ARM64 cpuidle logic cpuidle: mvebu: Fix duplicate flags assignment sched/fair: Limit sched slice duration ...
| * | cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUGPeter Zijlstra2023-01-311-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to avoid WARN/BUG from generating nested or even recursive warnings, force rcu_is_watching() true during WARN/lockdep_rcu_suspicious(). Notably things like unwinding the stack can trigger rcu_dereference() warnings, which then triggers more unwinding which then triggers more warnings etc.. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230126151323.408156109@infradead.org
* | | Merge tag 'locking-core-2023-02-20' of ↵Linus Torvalds2023-02-202-37/+54
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - rwsem micro-optimizations - spinlock micro-optimizations - cleanups, simplifications * tag 'locking-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: vduse: Remove include of rwlock.h locking/lockdep: Remove lockdep_init_map_crosslock. x86/ACPI/boot: Use try_cmpxchg() in __acpi_{acquire,release}_global_lock() x86/PAT: Use try_cmpxchg() in set_page_memtype() locking/rwsem: Disable preemption in all down_write*() and up_write() code paths locking/rwsem: Disable preemption in all down_read*() and up_read() code paths locking/rwsem: Prevent non-first waiter from spinning in down_write() slowpath locking/qspinlock: Micro-optimize pending state waiting for unlock
| * | | locking/rwsem: Disable preemption in all down_write*() and up_write() code pathsWaiman Long2023-01-261-19/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The previous patch has disabled preemption in all the down_read() and up_read() code paths. For symmetry, this patch extends commit: 48dfb5d2560d ("locking/rwsem: Disable preemption while trying for rwsem lock") ... to have preemption disabled in all the down_write() and up_write() code paths, including downgrade_write(). Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230126003628.365092-4-longman@redhat.com
| * | | locking/rwsem: Disable preemption in all down_read*() and up_read() code pathsWaiman Long2023-01-261-6/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit: 91d2a812dfb9 ("locking/rwsem: Make handoff writer optimistically spin on owner") ... assumes that when the owner field is changed to NULL, the lock will become free soon. But commit: 48dfb5d2560d ("locking/rwsem: Disable preemption while trying for rwsem lock") ... disabled preemption when acquiring rwsem for write. However, preemption has not yet been disabled when acquiring a read lock on a rwsem. So a reader can add a RWSEM_READER_BIAS to count without setting owner to signal a reader, got preempted out by a RT task which then spins in the writer slowpath as owner remains NULL leading to live lock. One easy way to fix this problem is to disable preemption at all the down_read*() and up_read() code paths as implemented in this patch. Fixes: 91d2a812dfb9 ("locking/rwsem: Make handoff writer optimistically spin on owner") Reported-by: Mukesh Ojha <quic_mojha@quicinc.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230126003628.365092-3-longman@redhat.com
| * | | locking/rwsem: Prevent non-first waiter from spinning in down_write() slowpathWaiman Long2023-01-261-10/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A non-first waiter can potentially spin in the for loop of rwsem_down_write_slowpath() without sleeping but fail to acquire the lock even if the rwsem is free if the following sequence happens: Non-first RT waiter First waiter Lock holder ------------------- ------------ ----------- Acquire wait_lock rwsem_try_write_lock(): Set handoff bit if RT or wait too long Set waiter->handoff_set Release wait_lock Acquire wait_lock Inherit waiter->handoff_set Release wait_lock Clear owner Release lock if (waiter.handoff_set) { rwsem_spin_on_owner((); if (OWNER_NULL) goto trylock_again; } trylock_again: Acquire wait_lock rwsem_try_write_lock(): if (first->handoff_set && (waiter != first)) return false; Release wait_lock A non-first waiter cannot really acquire the rwsem even if it mistakenly believes that it can spin on OWNER_NULL value. If that waiter happens to be an RT task running on the same CPU as the first waiter, it can block the first waiter from acquiring the rwsem leading to live lock. Fix this problem by making sure that a non-first waiter cannot spin in the slowpath loop without sleeping. Fixes: d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Mukesh Ojha <quic_mojha@quicinc.com> Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230126003628.365092-2-longman@redhat.com
| * | | locking/qspinlock: Micro-optimize pending state waiting for unlockGuo Ren2023-01-051-2/+2
| |/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we're pending, we only care about lock value. The xchg_tail wouldn't affect the pending state. That means the hardware thread could stay in a sleep state and leaves the rest execution units' resources of pipeline to other hardware threads. This situation is the SMT scenarios in the same core. Not an entering low-power state situation. Of course, the granularity between cores is "cacheline", but the granularity between SMT hw threads of the same core could be "byte" which internal LSU handles. For example, when a hw-thread yields the resources of the core to other hw-threads, this patch could help the hw-thread stay in the sleep state and prevent it from being woken up by other hw-threads xchg_tail. Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/20230105021952.3090070-1-guoren@kernel.org Cc: Peter Zijlstra <peterz@infradead.org>
* / / rtmutex: Ensure that the top waiter is always woken upWander Lairson Costa2023-02-061-2/+3
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Let L1 and L2 be two spinlocks. Let T1 be a task holding L1 and blocked on L2. T1, currently, is the top waiter of L2. Let T2 be the task holding L2. Let T3 be a task trying to acquire L1. The following events will lead to a state in which the wait queue of L2 isn't empty, but no task actually holds the lock. T1 T2 T3 == == == spin_lock(L1) | raw_spin_lock(L1->wait_lock) | rtlock_slowlock_locked(L1) | | task_blocks_on_rt_mutex(L1, T3) | | | orig_waiter->lock = L1 | | | orig_waiter->task = T3 | | | raw_spin_unlock(L1->wait_lock) | | | rt_mutex_adjust_prio_chain(T1, L1, L2, orig_waiter, T3) spin_unlock(L2) | | | | | rt_mutex_slowunlock(L2) | | | | | | raw_spin_lock(L2->wait_lock) | | | | | | wakeup(T1) | | | | | | raw_spin_unlock(L2->wait_lock) | | | | | | | | waiter = T1->pi_blocked_on | | | | waiter == rt_mutex_top_waiter(L2) | | | | waiter->task == T1 | | | | raw_spin_lock(L2->wait_lock) | | | | dequeue(L2, waiter) | | | | update_prio(waiter, T1) | | | | enqueue(L2, waiter) | | | | waiter != rt_mutex_top_waiter(L2) | | | | L2->owner == NULL | | | | wakeup(T1) | | | | raw_spin_unlock(L2->wait_lock) T1 wakes up T1 != top_waiter(L2) schedule_rtlock() If the deadline of T1 is updated before the call to update_prio(), and the new deadline is greater than the deadline of the second top waiter, then after the requeue, T1 is no longer the top waiter, and the wrong task is woken up which will then go back to sleep because it is not the top waiter. This can be reproduced in PREEMPT_RT with stress-ng: while true; do stress-ng --sched deadline --sched-period 1000000000 \ --sched-runtime 800000000 --sched-deadline \ 1000000000 --mmapfork 23 -t 20 done A similar issue was pointed out by Thomas versus the cases where the top waiter drops out early due to a signal or timeout, which is a general issue for all regular rtmutex use cases, e.g. futex. The problematic code is in rt_mutex_adjust_prio_chain(): // Save the top waiter before dequeue/enqueue prerequeue_top_waiter = rt_mutex_top_waiter(lock); rt_mutex_dequeue(lock, waiter); waiter_update_prio(waiter, task); rt_mutex_enqueue(lock, waiter); // Lock has no owner? if (!rt_mutex_owner(lock)) { // Top waiter changed ----> if (prerequeue_top_waiter != rt_mutex_top_waiter(lock)) ----> wake_up_state(waiter->task, waiter->wake_state); This only takes the case into account where @waiter is the new top waiter due to the requeue operation. But it fails to handle the case where @waiter is not longer the top waiter due to the requeue operation. Ensure that the new top waiter is woken up so in all cases so it can take over the ownerless lock. [ tglx: Amend changelog, add Fixes tag ] Fixes: c014ef69b3ac ("locking/rtmutex: Add wake_state to rt_mutex_waiter") Signed-off-by: Wander Lairson Costa <wander@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230117172649.52465-1-wander@redhat.com Link: https://lore.kernel.org/r/20230202123020.14844-1-wander@redhat.com
* | Merge tag 'locking_urgent_for_v6.2_rc2' of ↵Linus Torvalds2023-01-012-12/+49
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Borislav Petkov: - Prevent the leaking of a debug timer in futex_waitv() - A preempt-RT mutex locking fix, adding the proper acquire semantics * tag 'locking_urgent_for_v6.2_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Fix futex_waitv() hrtimer debug object leak on kcalloc error rtmutex: Add acquire semantics for rtmutex lock acquisition slow path
| * rtmutex: Add acquire semantics for rtmutex lock acquisition slow pathMel Gorman2022-12-122-12/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Jan Kara reported the following bug triggering on 6.0.5-rt14 running dbench on XFS on arm64. kernel BUG at fs/inode.c:625! Internal error: Oops - BUG: 0 [#1] PREEMPT_RT SMP CPU: 11 PID: 6611 Comm: dbench Tainted: G E 6.0.0-rt14-rt+ #1 pc : clear_inode+0xa0/0xc0 lr : clear_inode+0x38/0xc0 Call trace: clear_inode+0xa0/0xc0 evict+0x160/0x180 iput+0x154/0x240 do_unlinkat+0x184/0x300 __arm64_sys_unlinkat+0x48/0xc0 el0_svc_common.constprop.4+0xe4/0x2c0 do_el0_svc+0xac/0x100 el0_svc+0x78/0x200 el0t_64_sync_handler+0x9c/0xc0 el0t_64_sync+0x19c/0x1a0 It also affects 6.1-rc7-rt5 and affects a preempt-rt fork of 5.14 so this is likely a bug that existed forever and only became visible when ARM support was added to preempt-rt. The same problem does not occur on x86-64 and he also reported that converting sb->s_inode_wblist_lock to raw_spinlock_t makes the problem disappear indicating that the RT spinlock variant is the problem. Which in turn means that RT mutexes on ARM64 and any other weakly ordered architecture are affected by this independent of RT. Will Deacon observed: "I'd be more inclined to be suspicious of the slowpath tbh, as we need to make sure that we have acquire semantics on all paths where the lock can be taken. Looking at the rtmutex code, this really isn't obvious to me -- for example, try_to_take_rt_mutex() appears to be able to return via the 'takeit' label without acquire semantics and it looks like we might be relying on the caller's subsequent _unlock_ of the wait_lock for ordering, but that will give us release semantics which aren't correct." Sebastian Andrzej Siewior prototyped a fix that does work based on that comment but it was a little bit overkill and added some fences that should not be necessary. The lock owner is updated with an IRQ-safe raw spinlock held, but the spin_unlock does not provide acquire semantics which are needed when acquiring a mutex. Adds the necessary acquire semantics for lock owner updates in the slow path acquisition and the waiter bit logic. It successfully completed 10 iterations of the dbench workload while the vanilla kernel fails on the first iteration. [ bigeasy@linutronix.de: Initial prototype fix ] Fixes: 700318d1d7b38 ("locking/rtmutex: Use acquire/release semantics") Fixes: 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20221202100223.6mevpbl7i6x5udfd@techsingularity.net
* | Merge tag 'mm-stable-2022-12-13' of ↵Linus Torvalds2022-12-131-1/+0
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - More userfaultfs work from Peter Xu - Several convert-to-folios series from Sidhartha Kumar and Huang Ying - Some filemap cleanups from Vishal Moola - David Hildenbrand added the ability to selftest anon memory COW handling - Some cpuset simplifications from Liu Shixin - Addition of vmalloc tracing support by Uladzislau Rezki - Some pagecache folioifications and simplifications from Matthew Wilcox - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use it - Miguel Ojeda contributed some cleanups for our use of the __no_sanitize_thread__ gcc keyword. This series should have been in the non-MM tree, my bad - Naoya Horiguchi improved the interaction between memory poisoning and memory section removal for huge pages - DAMON cleanups and tuneups from SeongJae Park - Tony Luck fixed the handling of COW faults against poisoned pages - Peter Xu utilized the PTE marker code for handling swapin errors - Hugh Dickins reworked compound page mapcount handling, simplifying it and making it more efficient - Removal of the autonuma savedwrite infrastructure from Nadav Amit and David Hildenbrand - zram support for multiple compression streams from Sergey Senozhatsky - David Hildenbrand reworked the GUP code's R/O long-term pinning so that drivers no longer need to use the FOLL_FORCE workaround which didn't work very well anyway - Mel Gorman altered the page allocator so that local IRQs can remnain enabled during per-cpu page allocations - Vishal Moola removed the try_to_release_page() wrapper - Stefan Roesch added some per-BDI sysfs tunables which are used to prevent network block devices from dirtying excessive amounts of pagecache - David Hildenbrand did some cleanup and repair work on KSM COW breaking - Nhat Pham and Johannes Weiner have implemented writeback in zswap's zsmalloc backend - Brian Foster has fixed a longstanding corner-case oddity in file[map]_write_and_wait_range() - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang Chen - Shiyang Ruan has done some work on fsdax, to make its reflink mode work better under xfstests. Better, but still not perfect - Christoph Hellwig has removed the .writepage() method from several filesystems. They only need .writepages() - Yosry Ahmed wrote a series which fixes the memcg reclaim target beancounting - David Hildenbrand has fixed some of our MM selftests for 32-bit machines - Many singleton patches, as usual * tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits) mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio mm: mmu_gather: allow more than one batch of delayed rmaps mm: fix typo in struct pglist_data code comment kmsan: fix memcpy tests mm: add cond_resched() in swapin_walk_pmd_entry() mm: do not show fs mm pc for VM_LOCKONFAULT pages selftests/vm: ksm_functional_tests: fixes for 32bit selftests/vm: cow: fix compile warning on 32bit selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem mm,thp,rmap: fix races between updates of subpages_mapcount mm: memcg: fix swapcached stat accounting mm: add nodes= arg to memory.reclaim mm: disable top-tier fallback to reclaim on proactive reclaim selftests: cgroup: make sure reclaim target memcg is unprotected selftests: cgroup: refactor proactive reclaim code to reclaim_until() mm: memcg: fix stale protection of reclaim target memcg mm/mmap: properly unaccount memory on mas_preallocate() failure omfs: remove ->writepage jfs: remove ->writepage ...
| * | lockdep: allow instrumenting lockdep.c with KMSANAlexander Potapenko2022-12-111-1/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Lockdep and KMSAN used to play badly together, causing deadlocks when KMSAN instrumentation of lockdep.c called lockdep functions recursively. Looks like this is no more the case, and a kernel can run (yet slower) with both KMSAN and lockdep enabled. This patch should fix false positives on wq_head->lock->dep_map, which KMSAN used to consider uninitialized because of lockdep.c not being instrumented. Link: https://lore.kernel.org/lkml/Y3b9AAEKp2Vr3e6O@sol.localdomain/ Link: https://lkml.kernel.org/r/20221128094541.2645890-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reported-by: Eric Biggers <ebiggers@kernel.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Marco Elver <elver@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* / treewide: use get_random_u32_below() instead of deprecated functionJason A. Donenfeld2022-11-181-2/+2
|/ | | | | | | | | | | | | | | | | | | | This is a simple mechanical transformation done by: @@ expression E; @@ - prandom_u32_max + get_random_u32_below (E) Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs Reviewed-by: SeongJae Park <sj@kernel.org> # for damon Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
* treewide: use prandom_u32_max() when possible, part 1Jason A. Donenfeld2022-10-111-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rather than incurring a division or requesting too many random bytes for the given range, use the prandom_u32_max() function, which only takes the minimum required bytes from the RNG and avoids divisions. This was done mechanically with this coccinelle script: @basic@ expression E; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u64; @@ ( - ((T)get_random_u32() % (E)) + prandom_u32_max(E) | - ((T)get_random_u32() & ((E) - 1)) + prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2) | - ((u64)(E) * get_random_u32() >> 32) + prandom_u32_max(E) | - ((T)get_random_u32() & ~PAGE_MASK) + prandom_u32_max(PAGE_SIZE) ) @multi_line@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; identifier RAND; expression E; @@ - RAND = get_random_u32(); ... when != RAND - RAND %= (E); + RAND = prandom_u32_max(E); // Find a potential literal @literal_mask@ expression LITERAL; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; position p; @@ ((T)get_random_u32()@p & (LITERAL)) // Add one to the literal. @script:python add_one@ literal << literal_mask.LITERAL; RESULT; @@ value = None if literal.startswith('0x'): value = int(literal, 16) elif literal[0] in '123456789': value = int(literal, 10) if value is None: print("I don't know how to handle %s" % (literal)) cocci.include_match(False) elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1: print("Skipping 0x%x for cleanup elsewhere" % (value)) cocci.include_match(False) elif value & (value + 1) != 0: print("Skipping 0x%x because it's not a power of two minus one" % (value)) cocci.include_match(False) elif literal.startswith('0x'): coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1)) else: coccinelle.RESULT = cocci.make_expr("%d" % (value + 1)) // Replace the literal mask with the calculated result. @plus_one@ expression literal_mask.LITERAL; position literal_mask.p; expression add_one.RESULT; identifier FUNC; @@ - (FUNC()@p & (LITERAL)) + prandom_u32_max(RESULT) @collapse_ret@ type T; identifier VAR; expression E; @@ { - T VAR; - VAR = (E); - return VAR; + return E; } @drop_var@ type T; identifier VAR; @@ { - T VAR; ... when != VAR } Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: KP Singh <kpsingh@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd Acked-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390 Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
* Merge tag 'mm-stable-2022-10-08' of ↵Linus Torvalds2022-10-101-1/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in linux-next for a couple of months without, to my knowledge, any negative reports (or any positive ones, come to that). - Also the Maple Tree from Liam Howlett. An overlapping range-based tree for vmas. It it apparently slightly more efficient in its own right, but is mainly targeted at enabling work to reduce mmap_lock contention. Liam has identified a number of other tree users in the kernel which could be beneficially onverted to mapletrees. Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat at [1]. This has yet to be addressed due to Liam's unfortunately timed vacation. He is now back and we'll get this fixed up. - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses clang-generated instrumentation to detect used-unintialized bugs down to the single bit level. KMSAN keeps finding bugs. New ones, as well as the legacy ones. - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of memory into THPs. - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support file/shmem-backed pages. - userfaultfd updates from Axel Rasmussen - zsmalloc cleanups from Alexey Romanov - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure - Huang Ying adds enhancements to NUMA balancing memory tiering mode's page promotion, with a new way of detecting hot pages. - memcg updates from Shakeel Butt: charging optimizations and reduced memory consumption. - memcg cleanups from Kairui Song. - memcg fixes and cleanups from Johannes Weiner. - Vishal Moola provides more folio conversions - Zhang Yi removed ll_rw_block() :( - migration enhancements from Peter Xu - migration error-path bugfixes from Huang Ying - Aneesh Kumar added ability for a device driver to alter the memory tiering promotion paths. For optimizations by PMEM drivers, DRM drivers, etc. - vma merging improvements from Jakub Matěn. - NUMA hinting cleanups from David Hildenbrand. - xu xin added aditional userspace visibility into KSM merging activity. - THP & KSM code consolidation from Qi Zheng. - more folio work from Matthew Wilcox. - KASAN updates from Andrey Konovalov. - DAMON cleanups from Kaixu Xia. - DAMON work from SeongJae Park: fixes, cleanups. - hugetlb sysfs cleanups from Muchun Song. - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core. Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1] * tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits) hugetlb: allocate vma lock for all sharable vmas hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer hugetlb: fix vma lock handling during split vma and range unmapping mglru: mm/vmscan.c: fix imprecise comments mm/mglru: don't sync disk for each aging cycle mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol mm: memcontrol: use do_memsw_account() in a few more places mm: memcontrol: deprecate swapaccounting=0 mode mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled mm/secretmem: remove reduntant return value mm/hugetlb: add available_huge_pages() func mm: remove unused inline functions from include/linux/mm_inline.h selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd selftests/vm: add thp collapse shmem testing selftests/vm: add thp collapse file and tmpfs testing selftests/vm: modularize thp collapse memory operations selftests/vm: dedup THP helpers mm/khugepaged: add tracepoint to hpage_collapse_scan_file() mm/madvise: add file and shmem support to MADV_COLLAPSE ...
| * kmsan: disable instrumentation of unsupported common kernel codeAlexander Potapenko2022-10-031-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | EFI stub cannot be linked with KMSAN runtime, so we disable instrumentation for it. Instrumenting kcov, stackdepot or lockdep leads to infinite recursion caused by instrumentation hooks calling instrumented code again. Link: https://lkml.kernel.org/r/20220915150417.722975-13-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* | Merge tag 'locking-core-2022-10-07' of ↵Linus Torvalds2022-10-107-43/+55
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - Disable preemption in rwsem_write_trylock()'s attempt to take the rwsem, to avoid RT tasks hogging the CPU, which managed to preempt this function after the owner has been cleared but before a new owner is set. Also add debug checks to enforce this. - Add __lockfunc to more slow path functions and add __sched to semaphore functions. - Mark spinlock APIs noinline when the respective CONFIG_INLINE_SPIN_* toggles are disabled, to reduce LTO text size. - Print more debug information when lockdep gets confused in look_up_lock_class(). - Improve header file abuse checks. - Misc cleanups * tag 'locking-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/lockdep: Print more debug information - report name and key when look_up_lock_class() got confused locking: Add __sched to semaphore functions locking/rwsem: Disable preemption while trying for rwsem lock locking: Detect includes rwlock.h outside of spinlock.h locking: Add __lockfunc to slow path functions locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabled selftests: futex: Fix 'the the' typo in comment
| * | locking/lockdep: Print more debug information - report name and key when ↵Tetsuo Handa2022-09-211-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | look_up_lock_class() got confused Printing this information will be helpful: ------------[ cut here ]------------ Looking for class "l2tp_sock" with key l2tp_socket_class, but found a different class "slock-AF_INET6" with the same key WARNING: CPU: 1 PID: 14195 at kernel/locking/lockdep.c:940 look_up_lock_class+0xcc/0x140 Modules linked in: CPU: 1 PID: 14195 Comm: a.out Not tainted 6.0.0-rc6-dirty #863 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 RIP: 0010:look_up_lock_class+0xcc/0x140 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/bd99391e-f787-efe9-5ec6-3c6dc4c587b0@I-love.SAKURA.ne.jp
| * | Merge tag 'v6.0-rc6' into locking/core, to refresh the branchIngo Molnar2022-09-211-1/+1
| |\| | | | | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | locking: Add __sched to semaphore functionsNamhyung Kim2022-09-151-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | The internal functions are marked with __sched already, let's do the same for external functions too so that we can skip them in the stack trace. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220909000803.4181857-1-namhyung@kernel.org
| * | locking/rwsem: Disable preemption while trying for rwsem lockGokul krishna Krishnakumar2022-09-151-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make the region inside the rwsem_write_trylock non preemptible. We observe RT task is hogging CPU when trying to acquire rwsem lock which was acquired by a kworker task but before the rwsem owner was set. Here is the scenario: 1. CFS task (affined to a particular CPU) takes rwsem lock. 2. CFS task gets preempted by a RT task before setting owner. 3. RT task (FIFO) is trying to acquire the lock, but spinning until RT throttling happens for the lock as the lock was taken by CFS task. This patch attempts to fix the above issue by disabling preemption until owner is set for the lock. While at it also fix the issues at the places where rwsem_{set,clear}_owner() are called. This also adds lockdep annotation of preemption disable in rwsem_{set,clear}_owner() on Peter Z. suggestion. Signed-off-by: Gokul krishna Krishnakumar <quic_gokukris@quicinc.com> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/1662661467-24203-1-git-send-email-quic_mojha@quicinc.com
| * | locking: Add __lockfunc to slow path functionsNamhyung Kim2022-08-193-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | So that we can skip the functions in the perf lock contention and other places like /proc/PID/wchan. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/20220810220346.1919485-1-namhyung@kernel.org
| * | locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabledAndi Kleen2022-08-041-28/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Otherwise LTO will inline them anyways and cause a large kernel text increase. Since the explicit intention here is to not inline them marking them noinline is good documentation even for the non-LTO case. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Martin Liska <mliska@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20220719110548.1544-1-jslaby@suse.cz
* | | locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked()Marco Elver2022-08-301-0/+6
| |/ |/| | | | | | | | | | | | | | | | | | | Implement simple accessors to probe percpu-rwsem's locked state: percpu_is_write_locked(), percpu_is_read_locked(). Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Ian Rogers <irogers@google.com> Link: https://lore.kernel.org/r/20220829124719.675715-11-elver@google.com
* | Merge tag 'rcu.2022.07.26a' of ↵Linus Torvalds2022-08-021-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull RCU updates from Paul McKenney: - Documentation updates - Miscellaneous fixes - Callback-offload updates, perhaps most notably a new RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be offloaded at boot time, regardless of kernel boot parameters. This is useful to battery-powered systems such as ChromeOS and Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot parameter prevents offloaded callbacks from interfering with real-time workloads and with energy-efficiency mechanisms - Polled grace-period updates, perhaps most notably making these APIs account for both normal and expedited grace periods - Tasks RCU updates, perhaps most notably reducing the CPU overhead of RCU tasks trace grace periods by more than a factor of two on a system with 15,000 tasks. The reduction is expected to increase with the number of tasks, so it seems reasonable to hypothesize that a system with 150,000 tasks might see a 20-fold reduction in CPU overhead - Torture-test updates - Updates that merge RCU's dyntick-idle tracking into context tracking, thus reducing the overhead of transitioning to kernel mode from either idle or nohz_full userspace execution for kernels that track context independently of RCU. This is expected to be helpful primarily for kernels built with CONFIG_NO_HZ_FULL=y * tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits) rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings rcu: Diagnose extended sync_rcu_do_polled_gp() loops rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings rcutorture: Test polled expedited grace-period primitives rcu: Add polled expedited grace-period primitives rcutorture: Verify that polled GP API sees synchronous grace periods rcu: Make Tiny RCU grace periods visible to polled APIs rcu: Make polled grace-period API account for expedited grace periods rcu: Switch polled grace-period APIs to ->gp_seq_polled rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty rcu/nocb: Add option to opt rcuo kthreads out of RT priority rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread() rcu/nocb: Add an option to offload all CPUs on boot rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order rcu/nocb: Add/del rdp to iterate from rcuog itself rcu/tree: Add comment to describe GP-done condition in fqs loop rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs() rcu/kvfree: Remove useless monitor_todo flag rcu: Cleanup RCU urgency state for offline CPU ...
| * context_tracking: Take idle eqs entrypoints over RCUFrederic Weisbecker2022-07-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Start with moving the idle extended quiescent states entrypoints to context tracking. For now those are dumb redirections to existing RCU calls. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* | Merge tag 'locking-core-2022-08-01' of ↵Linus Torvalds2022-08-011-3/+4
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "This was a fairly quiet cycle for the locking subsystem: - lockdep: Fix a handful of the more complex lockdep_init_map_*() primitives that can lose the lock_type & cause false reports. No such mishap was observed in the wild. - jump_label improvements: simplify the cross-arch support of initial NOP patching by making it arch-specific code (used on MIPS only), and remove the s390 initial NOP patching that was superfluous" * tag 'locking-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/lockdep: Fix lockdep_init_map_*() confusion jump_label: make initial NOP patching the special case jump_label: mips: move module NOP patching into arch code jump_label: s390: avoid pointless initial NOP patching
| * | locking/lockdep: Fix lockdep_init_map_*() confusionPeter Zijlstra2022-06-241-3/+4
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | 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) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YqyEDtoan20K0CVD@worktop.programming.kicks-ass.net
* / locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by ↵Waiman Long2022-07-301-10/+20
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | first waiter 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 <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: John Donnelly <john.p.donnelly@oracle.com> Tested-by: Mel Gorman <mgorman@techsingularity.net> Link: https://lore.kernel.org/r/20220622200419.778799-1-longman@redhat.com
* locking/lockdep: Use sched_clock() for random numbersSebastian Andrzej Siewior2022-06-131-1/+1
| | | | | | | | | | | | | | | | | | | | Since the rewrote of prandom_u32(), in the commit mentioned below, the function uses sleeping locks which extracing random numbers and filling the batch. This breaks lockdep on PREEMPT_RT because lock_pin_lock() disables interrupts while calling __lock_pin_lock(). This can't be moved earlier because the main user of the function (rq_pin_lock()) invokes that function after disabling interrupts in order to acquire the lock. The cookie does not require random numbers as its goal is to provide a random value in order to notice unexpected "unlock + lock" sites. Use sched_clock() to provide random numbers. Fixes: a0103f4d86f88 ("random32: use real rng for non-deterministic randomness") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YoNn3pTkm5+QzE5k@linutronix.de
* Merge tag 'sysctl-5.19-rc1' of ↵Linus Torvalds2022-05-261-2/+33
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux Pull sysctl updates from Luis Chamberlain: "For two kernel releases now kernel/sysctl.c has been being cleaned up slowly, since the tables were grossly long, sprinkled with tons of #ifdefs and all this caused merge conflicts with one susbystem or another. This tree was put together to help try to avoid conflicts with these cleanups going on different trees at time. So nothing exciting on this pull request, just cleanups. Thanks a lot to the Uniontech and Huawei folks for doing some of this nasty work" * tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (28 commits) sched: Fix build warning without CONFIG_SYSCTL reboot: Fix build warning without CONFIG_SYSCTL kernel/kexec_core: move kexec_core sysctls into its own file sysctl: minor cleanup in new_dir() ftrace: fix building with SYSCTL=y but DYNAMIC_FTRACE=n fs/proc: Introduce list_for_each_table_entry for proc sysctl mm: fix unused variable kernel warning when SYSCTL=n latencytop: move sysctl to its own file ftrace: fix building with SYSCTL=n but DYNAMIC_FTRACE=y ftrace: Fix build warning ftrace: move sysctl_ftrace_enabled to ftrace.c kernel/do_mount_initrd: move real_root_dev sysctls to its own file kernel/delayacct: move delayacct sysctls to its own file kernel/acct: move acct sysctls to its own file kernel/panic: move panic sysctls to its own file kernel/lockdep: move lockdep sysctls to its own file mm: move page-writeback sysctls to their own file mm: move oom_kill sysctls to their own file kernel/reboot: move reboot sysctls to its own file sched: Move energy_aware sysctls to topology.c ...
| * kernel/lockdep: move lockdep sysctls to its own filetangmeng2022-04-061-2/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. All filesystem syctls now get reviewed by fs folks. This commit follows the commit of fs, move the prove_locking and lock_stat sysctls to its own file, kernel/lockdep.c. Signed-off-by: tangmeng <tangmeng@uniontech.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
* | locking/qrwlock: Change "queue rwlock" to "queued rwlock"Waiman Long2022-05-111-4/+4
| | | | | | | | | | | | | | | | | | | | Queued rwlock was originally named "queue rwlock" which wasn't quite grammatically correct. However there are still some "queue rwlock" references in the code. Change those to "queued rwlock" for consistency. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220510192134.434753-1-longman@redhat.com
* | locking/mutex: Make contention tracepoints more consistent wrt adaptive spinningPeter Zijlstra2022-04-051-4/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Have the trace_contention_*() tracepoints consistently include adaptive spinning. In order to differentiate between the spinning and non-spinning states add LCB_F_MUTEX and combine with LCB_F_SPIN. The consequence is that a mutex contention can now triggler multiple _begin() tracepoints before triggering an _end(). Additionally, this fixes one path where mutex would trigger _end() without ever seeing a _begin(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
* | locking: Apply contention tracepoints in the slow pathNamhyung Kim2022-04-058-1/+63
| | | | | | | | | | | | | | | | | | | | | | Adding the lock contention tracepoints in various lock function slow paths. Note that each arch can define spinlock differently, I only added it only to the generic qspinlock for now. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Link: https://lkml.kernel.org/r/20220322185709.141236-3-namhyung@kernel.org
* | locking: Add lock contention tracepointsNamhyung Kim2022-04-052-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds two new lock contention tracepoints like below: * lock:contention_begin * lock:contention_end The lock:contention_begin takes a flags argument to classify locks. I found it useful to identify what kind of locks it's tracing like if it's spinning or sleeping, reader-writer lock, real-time, and per-cpu. Move tracepoint definitions into mutex.c so that we can use them without lockdep. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Link: https://lkml.kernel.org/r/20220322185709.141236-2-namhyung@kernel.org
* | locking/rwsem: Always try to wake waiters in out_nolock pathWaiman Long2022-04-051-10/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For writers, the out_nolock path will always attempt to wake up waiters. This may not be really necessary if the waiter to be removed is not the first one. For readers, no attempt to wake up waiter is being made. However, if the HANDOFF bit is set and the reader to be removed is the first waiter, the waiter behind it will inherit the HANDOFF bit and for a write lock waiter waking it up will allow it to spin on the lock to acquire it faster. So it can be beneficial to do a wakeup in this case. Add a new rwsem_del_wake_waiter() helper function to do that consistently for both reader and writer out_nolock paths. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220322152059.2182333-4-longman@redhat.com
* | locking/rwsem: Conditionally wake waiters in reader/writer slowpathsWaiman Long2022-04-051-36/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In an analysis of a recent vmcore, a reader-owned rwsem was found with 385 readers but no writer in the wait queue. That is kind of unusual but it may be caused by some race conditions that we have not fully understood yet. In such a case, all the readers in the wait queue should join the other reader-owners and acquire the read lock. In rwsem_down_write_slowpath(), an incoming writer will try to wake up the front readers under such circumstance. That is not the case for rwsem_down_read_slowpath(), add a new helper function rwsem_cond_wake_waiter() to do wakeup and use it in both reader and writer slowpaths to have a consistent and correct behavior. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220322152059.2182333-3-longman@redhat.com
* | locking/rwsem: No need to check for handoff bit if wait queue emptyWaiman Long2022-04-051-5/+4
| | | | | | | | | | | | | | | | | | | | | | Since commit d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent"), the handoff bit is always cleared if the wait queue becomes empty. There is no need to check for RWSEM_FLAG_HANDOFF when the wait list is known to be empty. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220322152059.2182333-2-longman@redhat.com
* | lockdep: Fix -Wunused-parameter for _THIS_IP_Nick Desaulniers2022-04-051-14/+8
|/ | | | | | | | | | | | | | | | While looking into a bug related to the compiler's handling of addresses of labels, I noticed some uses of _THIS_IP_ seemed unused in lockdep. Drive by cleanup. -Wunused-parameter: kernel/locking/lockdep.c:1383:22: warning: unused parameter 'ip' kernel/locking/lockdep.c:4246:48: warning: unused parameter 'ip' kernel/locking/lockdep.c:4844:19: warning: unused parameter 'ip' Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/20220314221909.2027027-1-ndesaulniers@google.com
* Merge tag 'locking-core-2022-03-21' of ↵Linus Torvalds2022-03-225-31/+76
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 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 filesWaiman Long2022-02-163-15/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220211035526.1329503-2-longman@redhat.com
| * locking: Add missing __sched attributesMinchan Kim2022-02-112-3/+4
| | | | | | | | | | | | | | | | | | | | 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 <minchan@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220115231657.84828-1-minchan@kernel.org
| * locking/lockdep: Avoid potential access of invalid memory in lock_classWaiman Long2022-01-251-9/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lkml.kernel.org/r/20220103023558.1377055-1-longman@redhat.com
| * lockdep: Use memset_startat() helper in reinit_class()Xiu Jianfeng2022-01-251-4/+1
| | | | | | | | | | | | | | | | | | use memset_startat() helper to simplify the code, there is no functional change in this patch. Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211213132618.105737-1-xiujianfeng@huawei.com
* | lockdep: Correct lock_classes index mappingCheng Jui Wang2022-02-111-2/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <cheng-jui.wang@mediatek.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Link: https://lore.kernel.org/r/20220210105011.21712-1-cheng-jui.wang@mediatek.com
* locking/rwlocks: introduce write_lock_nestedMinchan Kim2022-01-222-0/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | 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 <minchan@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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