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, 59 insertions, 0 deletions

diff --git a/arch/alpha/lib/strlen.S b/arch/alpha/lib/strlen.S
new file mode 100644
index 000000000..4fc6a6ff2
--- /dev/null
+++ b/arch/alpha/lib/strlen.S
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * strlen.S (c) 1995 David Mosberger (davidm@cs.arizona.edu)
+ *
+ * Finds length of a 0-terminated string.  Optimized for the
+ * Alpha architecture:
+ *
+ *	- memory accessed as aligned quadwords only
+ *	- uses bcmpge to compare 8 bytes in parallel
+ *	- does binary search to find 0 byte in last
+ *	  quadword (HAKMEM needed 12 instructions to
+ *	  do this instead of the 9 instructions that
+ *	  binary search needs).
+ */
+#include <linux/export.h>
+	.set noreorder
+	.set noat
+
+	.align 3
+
+	.globl	strlen
+	.ent	strlen
+
+strlen:
+	ldq_u	$1, 0($16)	# load first quadword ($16  may be misaligned)
+	lda	$2, -1($31)
+	insqh	$2, $16, $2
+	andnot	$16, 7, $0
+	or	$2, $1, $1
+	cmpbge	$31, $1, $2	# $2  <- bitmask: bit i == 1 <==> i-th byte == 0
+	bne	$2, found
+
+loop:	ldq	$1, 8($0)
+	addq	$0, 8, $0	# addr += 8
+	nop			# helps dual issue last two insns
+	cmpbge	$31, $1, $2
+	beq	$2, loop
+
+found:	blbs	$2, done	# make aligned case fast
+	negq	$2, $3
+	and	$2, $3, $2
+
+	and	$2, 0x0f, $1
+	addq	$0, 4, $3
+	cmoveq	$1, $3, $0
+
+	and	$2, 0x33, $1
+	addq	$0, 2, $3
+	cmoveq	$1, $3, $0
+
+	and	$2, 0x55, $1
+	addq	$0, 1, $3
+	cmoveq	$1, $3, $0
+
+done:	subq	$0, $16, $0
+	ret	$31, ($26)
+
+	.end	strlen
+	EXPORT_SYMBOL(strlen)