From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- .../sched/membarrier-sync-core/arch-support.txt | 69 ++++++++++++++++++++++ .../features/sched/numa-balancing/arch-support.txt | 30 ++++++++++ 2 files changed, 99 insertions(+) create mode 100644 Documentation/features/sched/membarrier-sync-core/arch-support.txt create mode 100644 Documentation/features/sched/numa-balancing/arch-support.txt (limited to 'Documentation/features/sched') diff --git a/Documentation/features/sched/membarrier-sync-core/arch-support.txt b/Documentation/features/sched/membarrier-sync-core/arch-support.txt new file mode 100644 index 000000000..7425d2b99 --- /dev/null +++ b/Documentation/features/sched/membarrier-sync-core/arch-support.txt @@ -0,0 +1,69 @@ +# +# Feature name: membarrier-sync-core +# Kconfig: ARCH_HAS_MEMBARRIER_SYNC_CORE +# description: arch supports core serializing membarrier +# +# Architecture requirements +# +# * arm/arm64/powerpc/s390 +# +# Rely on implicit context synchronization as a result of exception return +# when returning from IPI handler, and when returning to user-space. +# +# * riscv +# +# riscv uses xRET as return from interrupt and to return to user-space. +# +# Given that xRET is not core serializing, we rely on FENCE.I for providing +# core serialization: +# +# - by calling sync_core_before_usermode() on return from interrupt (cf. +# ipi_sync_core()), +# +# - via switch_mm() and sync_core_before_usermode() (respectively, for +# uthread->uthread and kthread->uthread transitions) before returning +# to user-space. +# +# The serialization in switch_mm() is activated by prepare_sync_core_cmd(). +# +# * x86 +# +# x86-32 uses IRET as return from interrupt, which takes care of the IPI. +# However, it uses both IRET and SYSEXIT to go back to user-space. The IRET +# instruction is core serializing, but not SYSEXIT. +# +# x86-64 uses IRET as return from interrupt, which takes care of the IPI. +# However, it can return to user-space through either SYSRETL (compat code), +# SYSRETQ, or IRET. +# +# Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely +# instead on write_cr3() performed by switch_mm() to provide core serialization +# after changing the current mm, and deal with the special case of kthread -> +# uthread (temporarily keeping current mm into active_mm) by issuing a +# sync_core_before_usermode() in that specific case. +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | TODO | + | arc: | TODO | + | arm: | ok | + | arm64: | ok | + | csky: | TODO | + | hexagon: | TODO | + | loongarch: | TODO | + | m68k: | TODO | + | microblaze: | TODO | + | mips: | TODO | + | nios2: | TODO | + | openrisc: | TODO | + | parisc: | TODO | + | powerpc: | ok | + | riscv: | ok | + | s390: | ok | + | sh: | TODO | + | sparc: | TODO | + | um: | TODO | + | x86: | ok | + | xtensa: | TODO | + ----------------------- diff --git a/Documentation/features/sched/numa-balancing/arch-support.txt b/Documentation/features/sched/numa-balancing/arch-support.txt new file mode 100644 index 000000000..984601c7c --- /dev/null +++ b/Documentation/features/sched/numa-balancing/arch-support.txt @@ -0,0 +1,30 @@ +# +# Feature name: numa-balancing +# Kconfig: ARCH_SUPPORTS_NUMA_BALANCING +# description: arch supports NUMA balancing +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | TODO | + | arc: | .. | + | arm: | .. | + | arm64: | ok | + | csky: | .. | + | hexagon: | .. | + | loongarch: | ok | + | m68k: | .. | + | microblaze: | .. | + | mips: | TODO | + | nios2: | .. | + | openrisc: | .. | + | parisc: | .. | + | powerpc: | ok | + | riscv: | ok | + | s390: | ok | + | sh: | .. | + | sparc: | TODO | + | um: | .. | + | x86: | ok | + | xtensa: | .. | + ----------------------- -- cgit v1.3.1