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, 237 insertions, 0 deletions

diff --git a/lib/crypto/aescfb.c b/lib/crypto/aescfb.c
new file mode 100644
index 000000000..82cd55436
--- /dev/null
+++ b/lib/crypto/aescfb.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Minimal library implementation of AES in CFB mode
+ *
+ * Copyright 2023 Google LLC
+ */
+
+#include <crypto/aes.h>
+#include <crypto/utils.h>
+#include <linux/export.h>
+#include <linux/module.h>
+
+/**
+ * aescfb_encrypt - Perform AES-CFB encryption on a block of data
+ *
+ * @key:	The AES-CFB key schedule
+ * @dst:	Pointer to the ciphertext output buffer
+ * @src:	Pointer the plaintext (may equal @dst for encryption in place)
+ * @len:	The size in bytes of the plaintext and ciphertext.
+ * @iv:		The initialization vector (IV) to use for this block of data
+ */
+void aescfb_encrypt(const struct aes_enckey *key, u8 *dst, const u8 *src,
+		    int len, const u8 iv[AES_BLOCK_SIZE])
+{
+	u8 ks[AES_BLOCK_SIZE];
+	const u8 *v = iv;
+
+	while (len > 0) {
+		aes_encrypt(key, ks, v);
+		crypto_xor_cpy(dst, src, ks, min(len, AES_BLOCK_SIZE));
+		v = dst;
+
+		dst += AES_BLOCK_SIZE;
+		src += AES_BLOCK_SIZE;
+		len -= AES_BLOCK_SIZE;
+	}
+
+	memzero_explicit(ks, sizeof(ks));
+}
+EXPORT_SYMBOL(aescfb_encrypt);
+
+/**
+ * aescfb_decrypt - Perform AES-CFB decryption on a block of data
+ *
+ * @key:	The AES-CFB key schedule
+ * @dst:	Pointer to the plaintext output buffer
+ * @src:	Pointer the ciphertext (may equal @dst for decryption in place)
+ * @len:	The size in bytes of the plaintext and ciphertext.
+ * @iv:		The initialization vector (IV) to use for this block of data
+ */
+void aescfb_decrypt(const struct aes_enckey *key, u8 *dst, const u8 *src,
+		    int len, const u8 iv[AES_BLOCK_SIZE])
+{
+	u8 ks[2][AES_BLOCK_SIZE];
+
+	aes_encrypt(key, ks[0], iv);
+
+	for (int i = 0; len > 0; i ^= 1) {
+		if (len > AES_BLOCK_SIZE)
+			/*
+			 * Generate the keystream for the next block before
+			 * performing the XOR, as that may update in place and
+			 * overwrite the ciphertext.
+			 */
+			aes_encrypt(key, ks[!i], src);
+
+		crypto_xor_cpy(dst, src, ks[i], min(len, AES_BLOCK_SIZE));
+
+		dst += AES_BLOCK_SIZE;
+		src += AES_BLOCK_SIZE;
+		len -= AES_BLOCK_SIZE;
+	}
+
+	memzero_explicit(ks, sizeof(ks));
+}
+EXPORT_SYMBOL(aescfb_decrypt);
+
+MODULE_DESCRIPTION("Generic AES-CFB library");
+MODULE_AUTHOR("Ard Biesheuvel <ardb@kernel.org>");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_CRYPTO_SELFTESTS
+
+/*
+ * Test code below. Vectors taken from crypto/testmgr.h
+ */
+
+static struct {
+	u8	ptext[64] __nonstring;
+	u8	ctext[64] __nonstring;
+
+	u8	key[AES_MAX_KEY_SIZE] __nonstring;
+	u8	iv[AES_BLOCK_SIZE] __nonstring;
+
+	int	klen;
+	int	len;
+} const aescfb_tv[] __initconst = {
+	{ /* From NIST SP800-38A */
+		.key    = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
+			  "\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
+		.klen	= 16,
+		.iv	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.ptext	= "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
+			  "\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
+			  "\xae\x2d\x8a\x57\x1e\x03\xac\x9c"
+			  "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51"
+			  "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11"
+			  "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef"
+			  "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17"
+			  "\xad\x2b\x41\x7b\xe6\x6c\x37\x10",
+		.ctext	= "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20"
+			  "\x33\x34\x49\xf8\xe8\x3c\xfb\x4a"
+			  "\xc8\xa6\x45\x37\xa0\xb3\xa9\x3f"
+			  "\xcd\xe3\xcd\xad\x9f\x1c\xe5\x8b"
+			  "\x26\x75\x1f\x67\xa3\xcb\xb1\x40"
+			  "\xb1\x80\x8c\xf1\x87\xa4\xf4\xdf"
+			  "\xc0\x4b\x05\x35\x7c\x5d\x1c\x0e"
+			  "\xea\xc4\xc6\x6f\x9f\xf7\xf2\xe6",
+		.len	= 64,
+	}, {
+		.key	= "\x8e\x73\xb0\xf7\xda\x0e\x64\x52"
+			  "\xc8\x10\xf3\x2b\x80\x90\x79\xe5"
+			  "\x62\xf8\xea\xd2\x52\x2c\x6b\x7b",
+		.klen	= 24,
+		.iv	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.ptext	= "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
+			  "\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
+			  "\xae\x2d\x8a\x57\x1e\x03\xac\x9c"
+			  "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51"
+			  "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11"
+			  "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef"
+			  "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17"
+			  "\xad\x2b\x41\x7b\xe6\x6c\x37\x10",
+		.ctext	= "\xcd\xc8\x0d\x6f\xdd\xf1\x8c\xab"
+			  "\x34\xc2\x59\x09\xc9\x9a\x41\x74"
+			  "\x67\xce\x7f\x7f\x81\x17\x36\x21"
+			  "\x96\x1a\x2b\x70\x17\x1d\x3d\x7a"
+			  "\x2e\x1e\x8a\x1d\xd5\x9b\x88\xb1"
+			  "\xc8\xe6\x0f\xed\x1e\xfa\xc4\xc9"
+			  "\xc0\x5f\x9f\x9c\xa9\x83\x4f\xa0"
+			  "\x42\xae\x8f\xba\x58\x4b\x09\xff",
+		.len	= 64,
+	}, {
+		.key	= "\x60\x3d\xeb\x10\x15\xca\x71\xbe"
+			  "\x2b\x73\xae\xf0\x85\x7d\x77\x81"
+			  "\x1f\x35\x2c\x07\x3b\x61\x08\xd7"
+			  "\x2d\x98\x10\xa3\x09\x14\xdf\xf4",
+		.klen	= 32,
+		.iv	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.ptext	= "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
+			  "\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
+			  "\xae\x2d\x8a\x57\x1e\x03\xac\x9c"
+			  "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51"
+			  "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11"
+			  "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef"
+			  "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17"
+			  "\xad\x2b\x41\x7b\xe6\x6c\x37\x10",
+		.ctext	= "\xdc\x7e\x84\xbf\xda\x79\x16\x4b"
+			  "\x7e\xcd\x84\x86\x98\x5d\x38\x60"
+			  "\x39\xff\xed\x14\x3b\x28\xb1\xc8"
+			  "\x32\x11\x3c\x63\x31\xe5\x40\x7b"
+			  "\xdf\x10\x13\x24\x15\xe5\x4b\x92"
+			  "\xa1\x3e\xd0\xa8\x26\x7a\xe2\xf9"
+			  "\x75\xa3\x85\x74\x1a\xb9\xce\xf8"
+			  "\x20\x31\x62\x3d\x55\xb1\xe4\x71",
+		.len	= 64,
+	}, { /* > 16 bytes, not a multiple of 16 bytes */
+		.key	= "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
+			  "\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
+		.klen	= 16,
+		.iv	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.ptext	= "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
+			  "\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
+			  "\xae",
+		.ctext	= "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20"
+			  "\x33\x34\x49\xf8\xe8\x3c\xfb\x4a"
+			  "\xc8",
+		.len	= 17,
+	}, { /* < 16 bytes */
+		.key	= "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
+			  "\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
+		.klen	= 16,
+		.iv	= "\x00\x01\x02\x03\x04\x05\x06\x07"
+			  "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
+		.ptext	= "\x6b\xc1\xbe\xe2\x2e\x40\x9f",
+		.ctext	= "\x3b\x3f\xd9\x2e\xb7\x2d\xad",
+		.len	= 7,
+	},
+};
+
+static int __init libaescfb_init(void)
+{
+	for (int i = 0; i < ARRAY_SIZE(aescfb_tv); i++) {
+		struct aes_enckey key;
+		u8 buf[64];
+
+		if (aes_prepareenckey(&key, aescfb_tv[i].key, aescfb_tv[i].klen)) {
+			pr_err("aes_prepareenckey() failed on vector %d\n", i);
+			return -ENODEV;
+		}
+
+		aescfb_encrypt(&key, buf, aescfb_tv[i].ptext, aescfb_tv[i].len,
+			       aescfb_tv[i].iv);
+		if (memcmp(buf, aescfb_tv[i].ctext, aescfb_tv[i].len)) {
+			pr_err("aescfb_encrypt() #1 failed on vector %d\n", i);
+			return -ENODEV;
+		}
+
+		/* decrypt in place */
+		aescfb_decrypt(&key, buf, buf, aescfb_tv[i].len, aescfb_tv[i].iv);
+		if (memcmp(buf, aescfb_tv[i].ptext, aescfb_tv[i].len)) {
+			pr_err("aescfb_decrypt() failed on vector %d\n", i);
+			return -ENODEV;
+		}
+
+		/* encrypt in place */
+		aescfb_encrypt(&key, buf, buf, aescfb_tv[i].len, aescfb_tv[i].iv);
+		if (memcmp(buf, aescfb_tv[i].ctext, aescfb_tv[i].len)) {
+			pr_err("aescfb_encrypt() #2 failed on vector %d\n", i);
+
+			return -ENODEV;
+		}
+
+	}
+	return 0;
+}
+module_init(libaescfb_init);
+
+static void __exit libaescfb_exit(void)
+{
+}
+module_exit(libaescfb_exit);
+#endif