user/sven/linux.git/include/linux/rcupdate.h, branch v6.16.1

rcu-tasks: Always inline rcu_irq_work_resched()

2025-04-01T07:12:17Z

Thanks to CONFIG_DEBUG_SECTION_MISMATCH, empty functions can be generated out of line. rcu_irq_work_resched() can be called from noinstr code, so make sure it's always inlined. Fixes: 564506495ca9 ("rcu/context-tracking: Move deferred nocb resched to context tracking") Reported-by: Randy Dunlap Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Frederic Weisbecker Cc: Paul E. McKenney Cc: Linus Torvalds Link: https://lore.kernel.org/r/e84f15f013c07e4c410d972e75620c53b62c1b3e.1743481539.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/d1eca076-fdde-484a-b33e-70e0d167c36d@infradead.org

Merge tag 'rcu-next-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

2025-03-25T02:41:37Z

Pull RCU updates from Boqun Feng: "Documentation: - Add broken-timing possibility to stallwarn.rst - Improve discussion of this_cpu_ptr(), add raw_cpu_ptr() - Document self-propagating callbacks - Point call_srcu() to call_rcu() for detailed memory ordering - Add CONFIG_RCU_LAZY delays to call_rcu() kernel-doc header - Clarify RCU_LAZY and RCU_LAZY_DEFAULT_OFF help text - Remove references to old grace-period-wait primitives srcu: - Introduce srcu_read_{un,}lock_fast(), which is similar to srcu_read_{un,}lock_lite(): avoid smp_mb()s in lock and unlock at the cost of calling synchronize_rcu() in synchronize_srcu() Moreover, by returning the percpu offset of the counter at srcu_read_lock_fast() time, srcu_read_unlock_fast() can avoid extra pointer dereferencing, which makes it faster than srcu_read_{un,}lock_lite() srcu_read_{un,}lock_fast() are intended to replace rcu_read_{un,}lock_trace() if possible RCU torture: - Add get_torture_init_jiffies() to return the start time of the test - Add a test_boost_holdoff module parameter to allow delaying boosting tests when building rcutorture as built-in - Add grace period sequence number logging at the beginning and end of failure/close-call results - Switch to hexadecimal for the expedited grace period sequence number in the rcu_exp_grace_period trace point - Make cur_ops->format_gp_seqs take buffer length - Move RCU_TORTURE_TEST_{CHK_RDR_STATE,LOG_CPU} to bool - Complain when invalid SRCU reader_flavor is specified - Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing, which forces SRCU uses atomics even when percpu ops are NMI safe, and use the Kconfig for SRCU lockdep testing Misc: - Split rcu_report_exp_cpu_mult() mask parameter and use for tracing - Remove READ_ONCE() for rdp->gpwrap access in __note_gp_changes() - Fix get_state_synchronize_rcu_full() GP-start detection - Move RCU Tasks self-tests to core_initcall() - Print segment lengths in show_rcu_nocb_gp_state() - Make RCU watch ct_kernel_exit_state() warning - Flush console log from kernel_power_off() - rcutorture: Allow a negative value for nfakewriters - rcu: Update TREE05.boot to test normal synchronize_rcu() - rcu: Use _full() API to debug synchronize_rcu() Make RCU handle PREEMPT_LAZY better: - Fix header guard for rcu_all_qs() - rcu: Rename PREEMPT_AUTO to PREEMPT_LAZY - Update __cond_resched comment about RCU quiescent states - Handle unstable rdp in rcu_read_unlock_strict() - Handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y - osnoise: Provide quiescent states - Adjust rcutorture with possible PREEMPT_RCU=n && PREEMPT_COUNT=y combination - Limit PREEMPT_RCU configurations - Make rcutorture senario TREE07 and senario TREE10 use PREEMPT_LAZY=y" * tag 'rcu-next-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits) rcutorture: Make scenario TREE07 build CONFIG_PREEMPT_LAZY=y rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y rcu: limit PREEMPT_RCU configurations rcutorture: Update ->extendables check for lazy preemption rcutorture: Update rcutorture_one_extend_check() for lazy preemption osnoise: provide quiescent states rcu: Use _full() API to debug synchronize_rcu() rcu: Update TREE05.boot to test normal synchronize_rcu() rcutorture: Allow a negative value for nfakewriters Flush console log from kernel_power_off() context_tracking: Make RCU watch ct_kernel_exit_state() warning rcu/nocb: Print segment lengths in show_rcu_nocb_gp_state() rcu-tasks: Move RCU Tasks self-tests to core_initcall() rcu: Fix get_state_synchronize_rcu_full() GP-start detection torture: Make SRCU lockdep testing use srcu_read_lock_nmisafe() srcu: Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing rcutorture: Complain when invalid SRCU reader_flavor is specified rcutorture: Move RCU_TORTURE_TEST_{CHK_RDR_STATE,LOG_CPU} to bool rcutorture: Make cur_ops->format_gp_seqs take buffer length rcutorture: Add ftrace-compatible timestamp to GP# failure/close-call output ...

Merge branches 'docs.2025.02.04a', 'lazypreempt.2025.03.04a', 'misc.2025.03.04a', 'srcu.2025.02.05a' and 'torture.2025.02.05a'

2025-03-05T02:47:32Z

rcu-tasks: Move RCU Tasks self-tests to core_initcall()

2025-03-05T02:44:28Z

The timer and hrtimer softirq processing has moved to dedicated threads for kernels built with CONFIG_IRQ_FORCED_THREADING=y. This results in timers not expiring until later in early boot, which in turn causes the RCU Tasks self-tests to hang in kernels built with CONFIG_PROVE_RCU=y, which further causes the entire kernel to hang. One fix would be to make timers work during this time, but there are no known users of RCU Tasks grace periods during that time, so no justification for the added complexity. Not yet, anyway. This commit therefore moves the call to rcu_init_tasks_generic() from kernel_init_freeable() to a core_initcall(). This works because the timer and hrtimer kthreads are created at early_initcall() time. Fixes: 49a17639508c3 ("softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT.") Signed-off-by: Paul E. McKenney Cc: Sebastian Andrzej Siewior Cc: Frederic Weisbecker Cc: Thomas Gleixner Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Masami Hiramatsu Cc: Tested-by: Sebastian Andrzej Siewior Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Boqun Feng

rcu: handle unstable rdp in rcu_read_unlock_strict()

2025-02-05T15:01:55Z

rcu_read_unlock_strict() can be called with preemption enabled which can make for an unstable rdp and a racy norm value. Fix this by dropping the preempt-count in __rcu_read_unlock() after the call to rcu_read_unlock_strict(), adjusting the preempt-count check appropriately. Suggested-by: Frederic Weisbecker Signed-off-by: Ankur Arora Reviewed-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng

rcu, slab: use a regular callback function for kvfree_rcu

2025-02-05T09:45:29Z

RCU has been special-casing callback function pointers that are integers lower than 4096 as offsets of rcu_head for kvfree() instead. The tree RCU implementation no longer does that as the batched kvfree_rcu() is not a simple call_rcu(). The tiny RCU still does, and the plan is also to make tree RCU use call_rcu() for SLUB_TINY configurations. Instead of teaching tree RCU again to special case the offsets, let's remove the special casing completely. Since there's no SLOB anymore, it is possible to create a callback function that can take a pointer to a middle of slab object with unknown offset and determine the object's pointer before freeing it, so implement that as kvfree_rcu_cb(). Large kmalloc and vmalloc allocations are handled simply by aligning down to page size. For that we retain the requirement that the offset is smaller than 4096. But we can remove __is_kvfree_rcu_offset() completely and instead just opencode the condition in the BUILD_BUG_ON() check. Reviewed-by: Joel Fernandes (Google) Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Paul E. McKenney Signed-off-by: Vlastimil Babka

slab, rcu: move TINY_RCU variant of kvfree_rcu() to SLAB

2025-02-05T09:45:12Z

Following the move of TREE_RCU implementation, let's move also the TINY_RCU one for consistency and subsequent refactoring. For simplicity, remove the separate inline __kvfree_call_rcu() as TINY_RCU is not meant for high-performance hardware anyway. Declare kvfree_call_rcu() in rcupdate.h to avoid header dependency issues. Also move the kvfree_rcu_barrier() declaration to slab.h Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: Joel Fernandes (Google) Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Paul E. McKenney Signed-off-by: Vlastimil Babka

rcu: Remove references to old grace-period-wait primitives

2025-02-05T05:50:06Z

The rcu_barrier_sched(), synchronize_sched(), and synchronize_rcu_bh() RCU API members have been gone for many years. This commit therefore removes non-historical instances of them. Reported-by: Joe Perches Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng

Rename .data.unlikely to .data..unlikely

2024-11-27T00:38:27Z

Commit 7ccaba5314ca ("consolidate WARN_...ONCE() static variables") was intended to collect all .data.unlikely sections into one chunk. However, this has not worked when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or CONFIG_LTO_CLANG is enabled, because .data.unlikely matches the .data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro. Commit cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case, providing a minimal fix for stable backporting. We were aware this did not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The plan was to apply correct fixes and then revert cb87481ee89d. [1] Seven years have passed since then, yet the #ifdef workaround remains in place. Using a ".." separator in the section name fixes the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG. [1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/ Fixes: cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") Signed-off-by: Masahiro Yamada

Merge branches 'context_tracking.15.08.24a', 'csd.lock.15.08.24a', 'nocb.09.09.24a', 'rcutorture.14.08.24a', 'rcustall.09.09.24a', 'srcu.12.08.24a', 'rcu.tasks.14.08.24a', 'rcu_scaling_tests.15.08.24a', 'fixes.12.08.24a' and 'misc.11.08.24a' into next.09.09.24a

2024-09-08T18:39:47Z