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authorLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 10:45:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 10:45:51 -0800
commit8cc01d43f882fa1f44d8aa6727a6ea783d8fbe3f (patch)
tree053ed1940a0ddb7ff2972c05637edf820772cbb8 /init
parent8ca8d89b43caf9a02a18414d6eeff966d2b14512 (diff)
parentbba8d3d17dc2678f9647962900aa421a18c25320 (diff)
downloadlwn-8cc01d43f882fa1f44d8aa6727a6ea783d8fbe3f.tar.gz
lwn-8cc01d43f882fa1f44d8aa6727a6ea783d8fbe3f.zip
Merge tag 'rcu.2023.02.10a' of 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() ...
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig1
1 files changed, 0 insertions, 1 deletions
diff --git a/init/Kconfig b/init/Kconfig
index e76dc579cfa2..18f0bf50c468 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1873,7 +1873,6 @@ config PERF_EVENTS
default y if PROFILING
depends on HAVE_PERF_EVENTS
select IRQ_WORK
- select SRCU
help
Enable kernel support for various performance events provided
by software and hardware.