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 HEADgrafted

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.

1 files changed, 166 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty
new file mode 100644
index 000000000..895c47f05
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-tty
@@ -0,0 +1,166 @@
+What:		/sys/class/tty/console/active
+Date:		Nov 2010
+Contact:	Kay Sievers <kay.sievers@vrfy.org>
+Description:
+		 Shows the list of currently configured
+		 console devices, like 'tty1 ttyS0'.
+		 The last entry in the file is the active
+		 device connected to /dev/console.
+		 The file supports poll() to detect virtual
+		 console switches.
+
+What:		/sys/class/tty/tty<x>/active
+Date:		Nov 2010
+Contact:	Kay Sievers <kay.sievers@vrfy.org>
+Description:
+		 Shows the currently active virtual console
+		 device, like 'tty1'.
+		 The file supports poll() to detect virtual
+		 console switches.
+
+What:		/sys/class/tty/ttyS<x>/uartclk
+Date:		Sep 2012
+Contact:	Tomas Hlavacek <tmshlvck@gmail.com>
+Description:
+		 Shows the current uartclk value associated with the
+		 UART port in serial_core, that is bound to TTY like ttyS0.
+		 uartclk = 16 * baud_base
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/type
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Shows the current tty type for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/line
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Shows the current tty line number for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/port
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Shows the current tty port I/O address for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/irq
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Shows the current primary interrupt for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/flags
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Show the tty port status flags for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/xmit_fifo_size
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Show the transmit FIFO size for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/close_delay
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		Show the closing delay time for this port in centiseconds.
+
+		These sysfs values expose the TIOCGSERIAL interface via
+		sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/closing_wait
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		Show the close wait time for this port in centiseconds.
+
+		Waiting forever is represented as 0. If waiting on close is
+		disabled then the value is 65535.
+
+		These sysfs values expose the TIOCGSERIAL interface via
+		sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/custom_divisor
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Show the custom divisor if any that is set on this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/io_type
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Show the I/O type that is to be used with the iomem base
+		 address.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/iomem_base
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 The I/O memory base for this port.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/iomem_reg_shift
+Date:		October 2012
+Contact:	Alan Cox <alan@linux.intel.com>
+Description:
+		 Show the register shift indicating the spacing to be used
+		 for accesses on this iomem address.
+
+		 These sysfs values expose the TIOCGSERIAL interface via
+		 sysfs rather than via ioctls.
+
+What:		/sys/class/tty/ttyS<x>/rx_trig_bytes
+Date:		May 2014
+Contact:	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
+Description:
+		 Shows current RX interrupt trigger bytes or sets the
+		 user specified value to change it for the FIFO buffer.
+		 Users can show or set this value regardless of opening the
+		 serial device file or not.
+
+		 The RX trigger can be set one of four kinds of values for UART
+		 serials. When users input a meaning less value to this I/F,
+		 the RX trigger is changed to the nearest lower value for the
+		 device specification. For example, when user sets 7bytes on
+		 16550A, which has 1/4/8/14 bytes trigger, the RX trigger is
+		 automatically changed to 4 bytes.
+
+What:		/sys/class/tty/ttyS<x>/console
+Date:		February 2020
+Contact:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Description:
+		 Allows user to detach or attach back the given device as
+		 kernel console. It shows and accepts a boolean variable.