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, 222 insertions, 0 deletions

diff --git a/fs/jffs2/compr_zlib.c b/fs/jffs2/compr_zlib.c
new file mode 100644
index 000000000..5698dae5d
--- /dev/null
+++ b/fs/jffs2/compr_zlib.c
@@ -0,0 +1,222 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#if !defined(__KERNEL__) && !defined(__ECOS)
+#error "The userspace support got too messy and was removed. Update your mkfs.jffs2"
+#endif
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/zlib.h>
+#include <linux/zutil.h>
+#include "nodelist.h"
+#include "compr.h"
+
+	/* Plan: call deflate() with avail_in == *sourcelen,
+		avail_out = *dstlen - 12 and flush == Z_FINISH.
+		If it doesn't manage to finish,	call it again with
+		avail_in == 0 and avail_out set to the remaining 12
+		bytes for it to clean up.
+	   Q: Is 12 bytes sufficient?
+	*/
+#define STREAM_END_SPACE 12
+
+static DEFINE_MUTEX(deflate_mutex);
+static DEFINE_MUTEX(inflate_mutex);
+static z_stream inf_strm, def_strm;
+
+#ifdef __KERNEL__ /* Linux-only */
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+
+static int __init alloc_workspaces(void)
+{
+	def_strm.workspace = vmalloc(zlib_deflate_workspacesize(MAX_WBITS,
+							MAX_MEM_LEVEL));
+	if (!def_strm.workspace)
+		return -ENOMEM;
+
+	jffs2_dbg(1, "Allocated %d bytes for deflate workspace\n",
+		  zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL));
+	inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
+	if (!inf_strm.workspace) {
+		vfree(def_strm.workspace);
+		return -ENOMEM;
+	}
+	jffs2_dbg(1, "Allocated %d bytes for inflate workspace\n",
+		  zlib_inflate_workspacesize());
+	return 0;
+}
+
+static void free_workspaces(void)
+{
+	vfree(def_strm.workspace);
+	vfree(inf_strm.workspace);
+}
+#else
+#define alloc_workspaces() (0)
+#define free_workspaces() do { } while(0)
+#endif /* __KERNEL__ */
+
+static int jffs2_zlib_compress(unsigned char *data_in,
+			       unsigned char *cpage_out,
+			       uint32_t *sourcelen, uint32_t *dstlen)
+{
+	int ret;
+
+	if (*dstlen <= STREAM_END_SPACE)
+		return -1;
+
+	mutex_lock(&deflate_mutex);
+
+	if (Z_OK != zlib_deflateInit(&def_strm, 3)) {
+		pr_warn("deflateInit failed\n");
+		mutex_unlock(&deflate_mutex);
+		return -1;
+	}
+
+	def_strm.next_in = data_in;
+	def_strm.total_in = 0;
+
+	def_strm.next_out = cpage_out;
+	def_strm.total_out = 0;
+
+	while (def_strm.total_out < *dstlen - STREAM_END_SPACE && def_strm.total_in < *sourcelen) {
+		def_strm.avail_out = *dstlen - (def_strm.total_out + STREAM_END_SPACE);
+		def_strm.avail_in = min_t(unsigned long,
+			(*sourcelen-def_strm.total_in), def_strm.avail_out);
+		jffs2_dbg(1, "calling deflate with avail_in %ld, avail_out %ld\n",
+			  def_strm.avail_in, def_strm.avail_out);
+		ret = zlib_deflate(&def_strm, Z_PARTIAL_FLUSH);
+		jffs2_dbg(1, "deflate returned with avail_in %ld, avail_out %ld, total_in %ld, total_out %ld\n",
+			  def_strm.avail_in, def_strm.avail_out,
+			  def_strm.total_in, def_strm.total_out);
+		if (ret != Z_OK) {
+			jffs2_dbg(1, "deflate in loop returned %d\n", ret);
+			zlib_deflateEnd(&def_strm);
+			mutex_unlock(&deflate_mutex);
+			return -1;
+		}
+	}
+	def_strm.avail_out += STREAM_END_SPACE;
+	def_strm.avail_in = 0;
+	ret = zlib_deflate(&def_strm, Z_FINISH);
+	zlib_deflateEnd(&def_strm);
+
+	if (ret != Z_STREAM_END) {
+		jffs2_dbg(1, "final deflate returned %d\n", ret);
+		ret = -1;
+		goto out;
+	}
+
+	if (def_strm.total_out >= def_strm.total_in) {
+		jffs2_dbg(1, "zlib compressed %ld bytes into %ld; failing\n",
+			  def_strm.total_in, def_strm.total_out);
+		ret = -1;
+		goto out;
+	}
+
+	jffs2_dbg(1, "zlib compressed %ld bytes into %ld\n",
+		  def_strm.total_in, def_strm.total_out);
+
+	*dstlen = def_strm.total_out;
+	*sourcelen = def_strm.total_in;
+	ret = 0;
+ out:
+	mutex_unlock(&deflate_mutex);
+	return ret;
+}
+
+static int jffs2_zlib_decompress(unsigned char *data_in,
+				 unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	int ret;
+	int wbits = MAX_WBITS;
+
+	mutex_lock(&inflate_mutex);
+
+	inf_strm.next_in = data_in;
+	inf_strm.avail_in = srclen;
+	inf_strm.total_in = 0;
+
+	inf_strm.next_out = cpage_out;
+	inf_strm.avail_out = destlen;
+	inf_strm.total_out = 0;
+
+	/* If it's deflate, and it's got no preset dictionary, then
+	   we can tell zlib to skip the adler32 check. */
+	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
+	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
+	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
+
+		jffs2_dbg(2, "inflate skipping adler32\n");
+		wbits = -((data_in[0] >> 4) + 8);
+		inf_strm.next_in += 2;
+		inf_strm.avail_in -= 2;
+	} else {
+		/* Let this remain D1 for now -- it should never happen */
+		jffs2_dbg(1, "inflate not skipping adler32\n");
+	}
+
+
+	if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
+		pr_warn("inflateInit failed\n");
+		mutex_unlock(&inflate_mutex);
+		return 1;
+	}
+
+	while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
+		;
+	if (ret != Z_STREAM_END) {
+		pr_notice("inflate returned %d\n", ret);
+	}
+	zlib_inflateEnd(&inf_strm);
+	mutex_unlock(&inflate_mutex);
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_zlib_comp = {
+    .priority = JFFS2_ZLIB_PRIORITY,
+    .name = "zlib",
+    .compr = JFFS2_COMPR_ZLIB,
+    .compress = &jffs2_zlib_compress,
+    .decompress = &jffs2_zlib_decompress,
+#ifdef JFFS2_ZLIB_DISABLED
+    .disabled = 1,
+#else
+    .disabled = 0,
+#endif
+};
+
+int __init jffs2_zlib_init(void)
+{
+    int ret;
+
+    ret = alloc_workspaces();
+    if (ret)
+	    return ret;
+
+    ret = jffs2_register_compressor(&jffs2_zlib_comp);
+    if (ret)
+	    free_workspaces();
+
+    return ret;
+}
+
+void jffs2_zlib_exit(void)
+{
+    jffs2_unregister_compressor(&jffs2_zlib_comp);
+    free_workspaces();
+}