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 no

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()
...

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Merge branch 'stall.2023.01.09a' into HEAD

stall.2023.01.09a: RCU CPU stall-warning updates.

Merge drm/drm-next into drm-misc-next

Backmerging into drm-misc-next to get DRM accelerator infrastructure,
which is required by ipuv driver.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge tag 'v6.2-rc3' into next

Merge with mainline to bring in timer_shutdown_sync() API.

rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts

The maximum value of RCU CPU stall-warning timeouts has historically been
five minutes (300 seconds). However, the recently in

rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts

The maximum value of RCU CPU stall-warning timeouts has historically been
five minutes (300 seconds). However, the recently introduced expedited
RCU CPU stall-warning timeout is instead limited to 21 seconds. This
causes problems for CI/fuzzing services such as syzkaller by obscuring
the issue in question with expedited RCU CPU stall-warning timeout splats.

This commit therefore sets the RCU_EXP_CPU_STALL_TIMEOUT Kconfig options
upper bound to 300000 milliseconds, which is 300 seconds (AKA 5 minutes).

[ paulmck: Apply feedback from Hillf Danton. ]
[ paulmck: Apply feedback from Geert Uytterhoeven. ]

Reported-by: Dave Chinner <david@fromorbit.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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rcu: Add RCU stall diagnosis information

Because RCU CPU stall warnings are driven from the scheduling-clock
interrupt handler, a workload consisting of a very large number of
short-duration hardwar

rcu: Add RCU stall diagnosis information

Because RCU CPU stall warnings are driven from the scheduling-clock
interrupt handler, a workload consisting of a very large number of
short-duration hardware interrupts can result in misleading stall-warning
messages. On systems supporting only a single level of interrupts,
that is, where interrupts handlers cannot be interrupted, this can
produce misleading diagnostics. The stack traces will show the
innocent-bystander interrupted task, not the interrupts that are
at the very least exacerbating the stall.

This situation can be improved by displaying the number of interrupts
and the CPU time that they have consumed. Diagnosing other types
of stalls can be eased by also providing the count of softirqs and
the CPU time that they consumed as well as the number of context
switches and the task-level CPU time consumed.

Consider the following output given this change:

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (1250 ticks this GP) <omitted>
rcu: hardirqs softirqs csw/system
rcu: number: 624 45 0
rcu: cputime: 69 1 2425 ==> 2500(ms)

This output shows that the number of hard and soft interrupts is small,
there are no context switches, and the system takes up a lot of time. This
indicates that the current task is looping with preemption disabled.

The impact on system performance is negligible because snapshot is
recorded only once for all continuous RCU stalls.

This added debugging information is suppressed by default and can be
enabled by building the kernel with CONFIG_RCU_CPU_STALL_CPUTIME=y or
by booting with rcupdate.rcu_cpu_stall_cputime=1.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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Merge drm/drm-next into drm-intel-next

Sync up with v6.2-rc1.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Merge drm/drm-next into drm-intel-gt-next

Sync after v6.2-rc1 landed in drm-next.

We need to get some dependencies in place before we can merge
the fixes series from Gwan-gyeong and Chris.

Referen

Merge drm/drm-next into drm-intel-gt-next

Sync after v6.2-rc1 landed in drm-next.

We need to get some dependencies in place before we can merge
the fixes series from Gwan-gyeong and Chris.

References: https://lore.kernel.org/all/Y6x5JCDnh2rvh4lA@intel.com/
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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Merge tag 'v6.2-rc1' into media_tree

Linux 6.2-rc1

* tag 'v6.2-rc1': (14398 commits)
Linux 6.2-rc1
treewide: Convert del_timer*() to timer_shutdown*()
pstore: Properly assign mem_type propert

Merge tag 'v6.2-rc1' into media_tree

Linux 6.2-rc1

* tag 'v6.2-rc1': (14398 commits)
Linux 6.2-rc1
treewide: Convert del_timer*() to timer_shutdown*()
pstore: Properly assign mem_type property
pstore: Make sure CONFIG_PSTORE_PMSG selects CONFIG_RT_MUTEXES
cfi: Fix CFI failure with KASAN
perf python: Fix splitting CC into compiler and options
afs: Stop implementing ->writepage()
afs: remove afs_cache_netfs and afs_zap_permits() declarations
afs: remove variable nr_servers
afs: Fix lost servers_outstanding count
ALSA: usb-audio: Add new quirk FIXED_RATE for JBL Quantum810 Wireless
ALSA: azt3328: Remove the unused function snd_azf3328_codec_outl()
gcov: add support for checksum field
test_maple_tree: add test for mas_spanning_rebalance() on insufficient data
maple_tree: fix mas_spanning_rebalance() on insufficient data
hugetlb: really allocate vma lock for all sharable vmas
kmsan: export kmsan_handle_urb
kmsan: include linux/vmalloc.h
mm/mempolicy: fix memory leak in set_mempolicy_home_node system call
mm, mremap: fix mremap() expanding vma with addr inside vma
...

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Merge wireless into wireless-next

Due to the two cherry picked commits from wireless to wireless-next we have
several conflicts in mt76. To avoid any bugs with conflicts merge wireless into
wireless

Merge wireless into wireless-next

Due to the two cherry picked commits from wireless to wireless-next we have
several conflicts in mt76. To avoid any bugs with conflicts merge wireless into
wireless-next.

96f134dc1964 wifi: mt76: handle possible mt76_rx_token_consume failures
fe13dad8992b wifi: mt76: dma: do not increment queue head if mt76_dma_add_buf fails

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Merge drm/drm-fixes into drm-misc-fixes

Let's start the fixes cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge remote-tracking branch 'torvalds/master' into perf/core

To resolve a trivial merge conflict with c302378bc157f6a7 ("libbpf:
Hashmap interface update to allow both long and void* keys/values"),

Merge remote-tracking branch 'torvalds/master' into perf/core

To resolve a trivial merge conflict with c302378bc157f6a7 ("libbpf:
Hashmap interface update to allow both long and void* keys/values"),
where a function present upstream was removed in the perf tools
development tree.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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Merge branch 'main' into zstd-linus

Merge tag 'printk-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

- Add NMI-safe SRCU reader API. It uses atomic_inc() instead of
th

Merge tag 'printk-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

- Add NMI-safe SRCU reader API. It uses atomic_inc() instead of
this_cpu_inc() on strong load-store architectures.

- Introduce new console_list_lock to synchronize a manipulation of the
list of registered consoles and their flags.

This is a first step in removing the big-kernel-lock-like behavior of
console_lock(). This semaphore still serializes console->write()
calbacks against:

- each other. It primary prevents potential races between early
and proper console drivers using the same device.

- suspend()/resume() callbacks and init() operations in some
drivers.

- various other operations in the tty/vt and framebufer
susbsystems. It is likely that console_lock() serializes even
operations that are not directly conflicting with the
console->write() callbacks here. This is the most complicated
big-kernel-lock aspect of the console_lock() that will be hard
to untangle.

- Introduce new console_srcu lock that is used to safely iterate and
access the registered console drivers under SRCU read lock.

This is a prerequisite for introducing atomic console drivers and
console kthreads. It will reduce the complexity of serialization
against normal consoles and console_lock(). Also it should remove the
risk of deadlock during critical situations, like Oops or panic, when
only atomic consoles are registered.

- Check whether the console is registered instead of enabled on many
locations. It was a historical leftover.

- Cleanly force a preferred console in xenfb code instead of a dirty
hack.

- A lot of code and comment clean ups and improvements.

* tag 'printk-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (47 commits)
printk: htmldocs: add missing description
tty: serial: sh-sci: use setup() callback for early console
printk: relieve console_lock of list synchronization duties
tty: serial: kgdboc: use console_list_lock to trap exit
tty: serial: kgdboc: synchronize tty_find_polling_driver() and register_console()
tty: serial: kgdboc: use console_list_lock for list traversal
tty: serial: kgdboc: use srcu console list iterator
proc: consoles: use console_list_lock for list iteration
tty: tty_io: use console_list_lock for list synchronization
printk, xen: fbfront: create/use safe function for forcing preferred
netconsole: avoid CON_ENABLED misuse to track registration
usb: early: xhci-dbc: use console_is_registered()
tty: serial: xilinx_uartps: use console_is_registered()
tty: serial: samsung_tty: use console_is_registered()
tty: serial: pic32_uart: use console_is_registered()
tty: serial: earlycon: use console_is_registered()
tty: hvc: use console_is_registered()
efi: earlycon: use console_is_registered()
tty: nfcon: use console_is_registered()
serial_core: replace uart_console_enabled() with uart_console_registered()
...

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Merge branch 'rework/console-list-lock' into for-linus

rcu: Make SRCU mandatory

Kernels configured with CONFIG_PRINTK=n and CONFIG_SRCU=n get build
failures. This causes trouble for deep embedded systems. But given
that there are more than 25 instance

rcu: Make SRCU mandatory

Kernels configured with CONFIG_PRINTK=n and CONFIG_SRCU=n get build
failures. This causes trouble for deep embedded systems. But given
that there are more than 25 instances of "select SRCU" in the kernel,
it is hard to believe that there are many kernels running in production
without SRCU. This commit therefore makes SRCU mandatory. The SRCU
Kconfig option remains for backwards compatibility, and will be removed
when it is no longer used.

[ paulmck: Update per kernel test robot feedback. ]

Reported-by: John Ogness <john.ogness@linutronix.de>
Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: <linux-arch@vger.kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: John Ogness <john.ogness@linutronix.de>

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Merge branch 'main' into zstd-next

Merge branch 'next' into for-linus

Prepare input updates for 6.1 merge window.

Merge drm/drm-next into drm-intel-gt-next

Daniele needs 84d4333c1e28 ("misc/mei: Add NULL check to component match
callback functions") in order to merge the DG2 HuC patches.

Signed-off-by: Tvrtko

Merge drm/drm-next into drm-intel-gt-next

Daniele needs 84d4333c1e28 ("misc/mei: Add NULL check to component match
callback functions") in order to merge the DG2 HuC patches.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

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Merge branch 'for-6.1/nvdimm' into libnvdimm-for-next

Add v6.1 content on top of some straggling updates that missed v6.0.

Merge branch 'mlx5-vfio' into mlx5-next

Merge net/mlx5 dependencies for device DMA logging.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Merge branch 'for-6.0/dax' into libnvdimm-fixes

Pick up another "Soft Reservation" fix for v6.0-final on top of some
straggling nvdimm fixes that missed v5.19.

Merge tag 'v6.0-rc6' into locking/core, to refresh the branch

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge drm/drm-next into drm-misc-next

We need 6.0-rc1 to merge the backlight rework PR.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge branch 'am5748-fix' into fixes