Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
 "Various misc subsystems, before getting into the post-linux-next
  material.

  41 patches.

  Subsystems affected by this patch series: procfs, misc, core-kernel,
  lib, checkpatch, init, pipe, minix, fat, cgroups, kexec, kdump,
  taskstats, panic, kcov, resource, and ubsan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (41 commits)
  Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang"
  kernel/resource: fix kfree() of bootmem memory again
  kcov: properly handle subsequent mmap calls
  kcov: split ioctl handling into locked and unlocked parts
  panic: move panic_print before kmsg dumpers
  panic: add option to dump all CPUs backtraces in panic_print
  docs: sysctl/kernel: add missing bit to panic_print
  taskstats: remove unneeded dead assignment
  kasan: no need to unset panic_on_warn in end_report()
  ubsan: no need to unset panic_on_warn in ubsan_epilogue()
  panic: unset panic_on_warn inside panic()
  docs: kdump: add scp example to write out the dump file
  docs: kdump: update description about sysfs file system support
  arm64: mm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  x86/setup: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  kexec: make crashk_res, crashk_low_res and crash_notes symbols always visible
  cgroup: use irqsave in cgroup_rstat_flush_locked().
  fat: use pointer to simple type in put_user()
  minix: fix bug when opening a file with O_DIRECT
  ...

34 files changed, 311 insertions, 303 deletions

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index cb30ca3df27c..a748e7eb4429 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -146,9 +146,9 @@ System kernel config options
 	CONFIG_SYSFS=y
 
    Note that "sysfs file system support" might not appear in the "Pseudo
-   filesystems" menu if "Configure standard kernel features (for small
-   systems)" is not enabled in "General Setup." In this case, check the
-   .config file itself to ensure that sysfs is turned on, as follows::
+   filesystems" menu if "Configure standard kernel features (expert users)"
+   is not enabled in "General Setup." In this case, check the .config file
+   itself to ensure that sysfs is turned on, as follows::
 
 	grep 'CONFIG_SYSFS' .config
 
@@ -533,6 +533,10 @@ the following command::
 
    cp /proc/vmcore <dump-file>
 
+or use scp to write out the dump file between hosts on a network, e.g::
+
+   scp /proc/vmcore remote_username@remote_ip:<dump-file>
+
 You can also use makedumpfile utility to write out the dump file
 with specified options to filter out unwanted contents, e.g::
 
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9927564db88e..b7ccaa2ea867 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3792,6 +3792,11 @@
 			bit 3: print locks info if CONFIG_LOCKDEP is on
 			bit 4: print ftrace buffer
 			bit 5: print all printk messages in buffer
+			bit 6: print all CPUs backtrace (if available in the arch)
+			*Be aware* that this option may print a _lot_ of lines,
+			so there are risks of losing older messages in the log.
+			Use this option carefully, maybe worth to setup a
+			bigger log buffer with "log_buf_len" along with this.
 
 	panic_on_taint=	Bitmask for conditionally calling panic() in add_taint()
 			Format: <hex>[,nousertaint]
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 803c60bf21d3..1144ea3229a3 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -763,6 +763,8 @@ bit 1  print system memory info
 bit 2  print timer info
 bit 3  print locks info if ``CONFIG_LOCKDEP`` is on
 bit 4  print ftrace buffer
+bit 5  print all printk messages in buffer
+bit 6  print all CPUs backtrace (if available in the arch)
 =====  ============================================
 
 So for example to print tasks and memory info on panic, user can::
diff --git a/Documentation/dev-tools/sparse.rst b/Documentation/dev-tools/sparse.rst
index 02102be7ff49..dc791c8d84d1 100644
--- a/Documentation/dev-tools/sparse.rst
+++ b/Documentation/dev-tools/sparse.rst
@@ -100,3 +100,5 @@ have already built it.
 
 The optional make variable CF can be used to pass arguments to sparse.  The
 build system passes -Wbitwise to sparse automatically.
+
+Note that sparse defines the __CHECKER__ preprocessor symbol.
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9e26ec80d317..8ac25f19084e 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -90,7 +90,6 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
 phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1;
 #endif
 
-#ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
@@ -104,6 +103,9 @@ static void __init reserve_crashkernel(void)
 	unsigned long long crash_max = arm64_dma_phys_limit;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
 	/* no crashkernel= or invalid value specified */
@@ -136,11 +138,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-#else
-static void __init reserve_crashkernel(void)
-{
-}
-#endif /* CONFIG_KEXEC_CORE */
 
 /*
  * Return the maximum physical address for a zone accessible by the given bits
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 0d588032d6e6..f6275b317129 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -957,7 +957,6 @@ static inline void setup_vm_final(void)
 }
 #endif /* CONFIG_MMU */
 
-#ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
@@ -974,6 +973,8 @@ static void __init reserve_crashkernel(void)
 
 	int ret = 0;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
 	/*
 	 * Don't reserve a region for a crash kernel on a crash kernel
 	 * since it doesn't make much sense and we have limited memory
@@ -1023,7 +1024,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-#endif /* CONFIG_KEXEC_CORE */
 
 void __init paging_init(void)
 {
@@ -1037,9 +1037,7 @@ void __init misc_mem_init(void)
 	arch_numa_init();
 	sparse_init();
 	zone_sizes_init();
-#ifdef CONFIG_KEXEC_CORE
 	reserve_crashkernel();
-#endif
 	memblock_dump_all();
 }
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 90d7e1788c91..c95b9ac5a457 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -411,8 +411,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
  * --------- Crashkernel reservation ------------------------------
  */
 
-#ifdef CONFIG_KEXEC_CORE
-
 /* 16M alignment for crash kernel regions */
 #define CRASH_ALIGN		SZ_16M
 
@@ -490,6 +488,9 @@ static void __init reserve_crashkernel(void)
 	bool high = false;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
 	total_mem = memblock_phys_mem_size();
 
 	/* crashkernel=XM */
@@ -555,11 +556,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.end   = crash_base + crash_size - 1;
 	insert_resource(&iomem_resource, &crashk_res);
 }
-#else
-static void __init reserve_crashkernel(void)
-{
-}
-#endif
 
 static struct resource standard_io_resources[] = {
 	{ .name = "dma1", .start = 0x00, .end = 0x1f,
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index c4a274285858..249825017da7 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -722,7 +722,7 @@ static int func(struct dir_context *ctx, const char *name, int name_len,   \
 		if (name_len >= sizeof(d1->d_name))			   \
 			name_len = sizeof(d1->d_name) - 1;		   \
 									   \
-		if (put_user(0, d2->d_name)			||	   \
+		if (put_user(0, &d2->d_name[0])			||	   \
 		    put_user(0, &d2->d_reclen)			||	   \
 		    copy_to_user(d1->d_name, name, name_len)	||	   \
 		    put_user(0, d1->d_name + name_len)		||	   \
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index 700228c7f38b..f1a6610e4ee6 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -448,7 +448,8 @@ static const struct address_space_operations minix_aops = {
 	.writepage = minix_writepage,
 	.write_begin = minix_write_begin,
 	.write_end = generic_write_end,
-	.bmap = minix_bmap
+	.bmap = minix_bmap,
+	.direct_IO = noop_direct_IO
 };
 
 static const struct inode_operations minix_symlink_inode_operations = {
diff --git a/fs/pipe.c b/fs/pipe.c
index 2667db9506e2..9648ac15164a 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -607,7 +607,7 @@ out:
 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct pipe_inode_info *pipe = filp->private_data;
-	int count, head, tail, mask;
+	unsigned int count, head, tail, mask;
 
 	switch (cmd) {
 	case FIONREAD:
@@ -804,7 +804,7 @@ struct pipe_inode_info *alloc_pipe_info(void)
 	if (too_many_pipe_buffers_hard(user_bufs) && pipe_is_unprivileged_user())
 		goto out_revert_acct;
 
-	pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
+	pipe->bufs = kvcalloc(pipe_bufs, sizeof(struct pipe_buffer),
 			     GFP_KERNEL_ACCOUNT);
 
 	if (pipe->bufs) {
@@ -829,7 +829,7 @@ out_free_uid:
 
 void free_pipe_info(struct pipe_inode_info *pipe)
 {
-	int i;
+	unsigned int i;
 
 #ifdef CONFIG_WATCH_QUEUE
 	if (pipe->watch_queue)
@@ -849,7 +849,7 @@ void free_pipe_info(struct pipe_inode_info *pipe)
 #endif
 	if (pipe->tmp_page)
 		__free_page(pipe->tmp_page);
-	kfree(pipe->bufs);
+	kvfree(pipe->bufs);
 	kfree(pipe);
 }
 
@@ -1264,8 +1264,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
 	if (nr_slots < n)
 		return -EBUSY;
 
-	bufs = kcalloc(nr_slots, sizeof(*bufs),
-		       GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
+	bufs = kvcalloc(nr_slots, sizeof(*bufs), GFP_KERNEL_ACCOUNT);
 	if (unlikely(!bufs))
 		return -ENOMEM;
 
@@ -1292,7 +1291,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
 	head = n;
 	tail = 0;
 
-	kfree(pipe->bufs);
+	kvfree(pipe->bufs);
 	pipe->bufs = bufs;
 	pipe->ring_size = nr_slots;
 	if (pipe->max_usage > nr_slots)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d654ce7150fd..76bf1aa3cfe8 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1764,25 +1764,25 @@ out:
 
 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
 {
-	char *tmp = (char *)__get_free_page(GFP_KERNEL);
+	char *tmp = kmalloc(PATH_MAX, GFP_KERNEL);
 	char *pathname;
 	int len;
 
 	if (!tmp)
 		return -ENOMEM;
 
-	pathname = d_path(path, tmp, PAGE_SIZE);
+	pathname = d_path(path, tmp, PATH_MAX);
 	len = PTR_ERR(pathname);
 	if (IS_ERR(pathname))
 		goto out;
-	len = tmp + PAGE_SIZE - 1 - pathname;
+	len = tmp + PATH_MAX - 1 - pathname;
 
 	if (len > buflen)
 		len = buflen;
 	if (copy_to_user(buffer, pathname, len))
 		len = -EFAULT;
  out:
-	free_page((unsigned long)tmp);
+	kfree(tmp);
 	return len;
 }
 
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 702754dd1daf..6f1b8ddc6f7a 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -62,7 +62,8 @@ core_param(novmcoredd, vmcoredd_disabled, bool, 0);
 /* Device Dump Size */
 static size_t vmcoredd_orig_sz;
 
-static DECLARE_RWSEM(vmcore_cb_rwsem);
+static DEFINE_SPINLOCK(vmcore_cb_lock);
+DEFINE_STATIC_SRCU(vmcore_cb_srcu);
 /* List of registered vmcore callbacks. */
 static LIST_HEAD(vmcore_cb_list);
 /* Whether the vmcore has been opened once. */
@@ -70,8 +71,8 @@ static bool vmcore_opened;
 
 void register_vmcore_cb(struct vmcore_cb *cb)
 {
-	down_write(&vmcore_cb_rwsem);
 	INIT_LIST_HEAD(&cb->next);
+	spin_lock(&vmcore_cb_lock);
 	list_add_tail(&cb->next, &vmcore_cb_list);
 	/*
 	 * Registering a vmcore callback after the vmcore was opened is
@@ -79,14 +80,14 @@ void register_vmcore_cb(struct vmcore_cb *cb)
 	 */
 	if (vmcore_opened)
 		pr_warn_once("Unexpected vmcore callback registration\n");
-	up_write(&vmcore_cb_rwsem);
+	spin_unlock(&vmcore_cb_lock);
 }
 EXPORT_SYMBOL_GPL(register_vmcore_cb);
 
 void unregister_vmcore_cb(struct vmcore_cb *cb)
 {
-	down_write(&vmcore_cb_rwsem);
-	list_del(&cb->next);
+	spin_lock(&vmcore_cb_lock);
+	list_del_rcu(&cb->next);
 	/*
 	 * Unregistering a vmcore callback after the vmcore was opened is
 	 * very unusual (e.g., forced driver removal), but we cannot stop
@@ -94,7 +95,9 @@ void unregister_vmcore_cb(struct vmcore_cb *cb)
 	 */
 	if (vmcore_opened)
 		pr_warn_once("Unexpected vmcore callback unregistration\n");
-	up_write(&vmcore_cb_rwsem);
+	spin_unlock(&vmcore_cb_lock);
+
+	synchronize_srcu(&vmcore_cb_srcu);
 }
 EXPORT_SYMBOL_GPL(unregister_vmcore_cb);
 
@@ -103,9 +106,8 @@ static bool pfn_is_ram(unsigned long pfn)
 	struct vmcore_cb *cb;
 	bool ret = true;
 
-	lockdep_assert_held_read(&vmcore_cb_rwsem);
-
-	list_for_each_entry(cb, &vmcore_cb_list, next) {
+	list_for_each_entry_srcu(cb, &vmcore_cb_list, next,
+				 srcu_read_lock_held(&vmcore_cb_srcu)) {
 		if (unlikely(!cb->pfn_is_ram))
 			continue;
 		ret = cb->pfn_is_ram(cb, pfn);
@@ -118,9 +120,9 @@ static bool pfn_is_ram(unsigned long pfn)
 
 static int open_vmcore(struct inode *inode, struct file *file)
 {
-	down_read(&vmcore_cb_rwsem);
+	spin_lock(&vmcore_cb_lock);
 	vmcore_opened = true;
-	up_read(&vmcore_cb_rwsem);
+	spin_unlock(&vmcore_cb_lock);
 
 	return 0;
 }
@@ -133,6 +135,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
 	unsigned long pfn, offset;
 	size_t nr_bytes;
 	ssize_t read = 0, tmp;
+	int idx;
 
 	if (!count)
 		return 0;
@@ -140,7 +143,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
 	offset = (unsigned long)(*ppos % PAGE_SIZE);
 	pfn = (unsigned long)(*ppos / PAGE_SIZE);
 
-	down_read(&vmcore_cb_rwsem);
+	idx = srcu_read_lock(&vmcore_cb_srcu);
 	do {
 		if (count > (PAGE_SIZE - offset))
 			nr_bytes = PAGE_SIZE - offset;
@@ -165,7 +168,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
 						       offset, userbuf);
 		}
 		if (tmp < 0) {
-			up_read(&vmcore_cb_rwsem);
+			srcu_read_unlock(&vmcore_cb_srcu, idx);
 			return tmp;
 		}
 
@@ -176,8 +179,8 @@ ssize_t read_from_oldmem(char *buf, size_t count,
 		++pfn;
 		offset = 0;
 	} while (count);
+	srcu_read_unlock(&vmcore_cb_srcu, idx);
 
-	up_read(&vmcore_cb_rwsem);
 	return read;
 }
 
@@ -477,7 +480,7 @@ static const struct vm_operations_struct vmcore_mmap_ops = {
 
 /**
  * vmcore_alloc_buf - allocate buffer in vmalloc memory
- * @sizez: size of buffer
+ * @size: size of buffer
  *
  * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
  * the buffer to user-space by means of remap_vmalloc_range().
@@ -568,18 +571,18 @@ static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
 			    unsigned long from, unsigned long pfn,
 			    unsigned long size, pgprot_t prot)
 {
-	int ret;
+	int ret, idx;
 
 	/*
-	 * Check if oldmem_pfn_is_ram was registered to avoid
-	 * looping over all pages without a reason.
+	 * Check if a callback was registered to avoid looping over all
+	 * pages without a reason.
 	 */
-	down_read(&vmcore_cb_rwsem);
+	idx = srcu_read_lock(&vmcore_cb_srcu);
 	if (!list_empty(&vmcore_cb_list))
 		ret = remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
 	else
 		ret = remap_oldmem_pfn_range(vma, from, pfn, size, prot);
-	up_read(&vmcore_cb_rwsem);
+	srcu_read_unlock(&vmcore_cb_srcu, idx);
 	return ret;
 }
 
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 6093fa6db260..c9be1657f03d 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -19,6 +19,9 @@
  *
  * Example:
  *
+ *  #include <linux/bitfield.h>
+ *  #include <linux/bits.h>
+ *
  *  #define REG_FIELD_A  GENMASK(6, 0)
  *  #define REG_FIELD_B  BIT(7)
  *  #define REG_FIELD_C  GENMASK(15, 8)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 1bc760ba400c..1c2c33ae1b37 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -11,6 +11,7 @@
 # define BTF_TYPE_TAG(value) /* nothing */
 #endif
 
+/* sparse defines __CHECKER__; see Documentation/dev-tools/sparse.rst */
 #ifdef __CHECKER__
 /* address spaces */
 # define __kernel	__attribute__((address_space(0)))
@@ -144,8 +145,6 @@ struct ftrace_likely_data {
  */
 #define __naked			__attribute__((__naked__)) notrace
 
-#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
-
 /*
  * Prefer gnu_inline, so that extern inline functions do not emit an
  * externally visible function. This makes extern inline behave as per gnu89
diff --git a/include/linux/init.h b/include/linux/init.h
index d82b4b2e1d25..baf0b29a7010 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -320,12 +320,19 @@ struct obs_kernel_param {
 		__aligned(__alignof__(struct obs_kernel_param))		\
 		= { __setup_str_##unique_id, fn, early }
 
+/*
+ * NOTE: __setup functions return values:
+ * @fn returns 1 (or non-zero) if the option argument is "handled"
+ * and returns 0 if the option argument is "not handled".
+ */
 #define __setup(str, fn)						\
 	__setup_param(str, fn, fn, 0)
 
 /*
- * NOTE: fn is as per module_param, not __setup!
- * Emits warning if fn returns non-zero.
+ * NOTE: @fn is as per module_param, not __setup!
+ * I.e., @fn returns 0 for no error or non-zero for error
+ * (possibly @fn returns a -errno value, but it does not matter).
+ * Emits warning if @fn returns non-zero.
  */
 #define early_param(str, fn)						\
 	__setup_param(str, fn, fn, 1)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0c994ae37729..58d1b58a971e 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -20,6 +20,12 @@
 
 #include <uapi/linux/kexec.h>
 
+/* Location of a reserved region to hold the crash kernel.
+ */
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
+extern note_buf_t __percpu *crash_notes;
+
 #ifdef CONFIG_KEXEC_CORE
 #include <linux/list.h>
 #include <linux/compat.h>
@@ -350,12 +356,6 @@ extern int kexec_load_disabled;
 #define KEXEC_FILE_FLAGS	(KEXEC_FILE_UNLOAD | KEXEC_FILE_ON_CRASH | \
 				 KEXEC_FILE_NO_INITRAMFS)
 
-/* Location of a reserved region to hold the crash kernel.
- */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
-extern note_buf_t __percpu *crash_notes;
-
 /* flag to track if kexec reboot is in progress */
 extern bool kexec_in_progress;
 
diff --git a/include/linux/log2.h b/include/linux/log2.h
index df0b155c2141..9f30d087a128 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -18,7 +18,7 @@
  * - the arch is not required to handle n==0 if implementing the fallback
  */
 #ifndef CONFIG_ARCH_HAS_ILOG2_U32
-static inline __attribute__((const))
+static __always_inline __attribute__((const))
 int __ilog2_u32(u32 n)
 {
 	return fls(n) - 1;
@@ -26,7 +26,7 @@ int __ilog2_u32(u32 n)
 #endif
 
 #ifndef CONFIG_ARCH_HAS_ILOG2_U64
-static inline __attribute__((const))
+static __always_inline __attribute__((const))
 int __ilog2_u64(u64 n)
 {
 	return fls64(n) - 1;
diff --git a/include/linux/stddef.h b/include/linux/stddef.h
index ca507bd5f808..929d67710cc5 100644
--- a/include/linux/stddef.h
+++ b/include/linux/stddef.h
@@ -13,11 +13,7 @@ enum {
 };
 
 #undef offsetof
-#ifdef __compiler_offsetof
-#define offsetof(TYPE, MEMBER)	__compiler_offsetof(TYPE, MEMBER)
-#else
-#define offsetof(TYPE, MEMBER)	((size_t)&((TYPE *)0)->MEMBER)
-#endif
+#define offsetof(TYPE, MEMBER)	__builtin_offsetof(TYPE, MEMBER)
 
 /**
  * sizeof_field() - Report the size of a struct field in bytes
diff --git a/include/uapi/linux/types.h b/include/uapi/linux/types.h
index f6d2f83cbe29..c4dc597f3dcf 100644
--- a/include/uapi/linux/types.h
+++ b/include/uapi/linux/types.h
@@ -19,12 +19,12 @@
  * any application/library that wants linux/types.h.
  */
 
+/* sparse defines __CHECKER__; see Documentation/dev-tools/sparse.rst */
 #ifdef __CHECKER__
-#define __bitwise__ __attribute__((bitwise))
+#define __bitwise	__attribute__((bitwise))
 #else
-#define __bitwise__
+#define __bitwise
 #endif
-#define __bitwise __bitwise__
 
 typedef __u16 __bitwise __le16;
 typedef __u16 __bitwise __be16;
diff --git a/init/main.c b/init/main.c
index 0c064c2c79fd..98182c3c2c4b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1192,7 +1192,7 @@ static int __init initcall_blacklist(char *str)
 		}
 	} while (str_entry);
 
-	return 0;
+	return 1;
 }
 
 static bool __init_or_module initcall_blacklisted(initcall_t fn)
@@ -1248,15 +1248,11 @@ trace_initcall_start_cb(void *data, initcall_t fn)
 static __init_or_module void
 trace_initcall_finish_cb(void *data, initcall_t fn, int ret)
 {
-	ktime_t *calltime = (ktime_t *)data;
-	ktime_t delta, rettime;
-	unsigned long long duration;
+	ktime_t rettime, *calltime = (ktime_t *)data;
 
 	rettime = ktime_get();
-	delta = ktime_sub(rettime, *calltime);
-	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 	printk(KERN_DEBUG "initcall %pS returned %d after %lld usecs\n",
-		 fn, ret, duration);
+		 fn, ret, (unsigned long long)ktime_us_delta(rettime, *calltime));
 }
 
 static ktime_t initcall_calltime;
@@ -1454,7 +1450,9 @@ static noinline void __init kernel_init_freeable(void);
 bool rodata_enabled __ro_after_init = true;
 static int __init set_debug_rodata(char *str)
 {
-	return strtobool(str, &rodata_enabled);
+	if (strtobool(str, &rodata_enabled))
+		pr_warn("Invalid option string for rodata: '%s'\n", str);
+	return 1;
 }
 __setup("rodata=", set_debug_rodata);
 #endif
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 29ea74f0eab3..24b5c2ab5598 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -153,8 +153,17 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
 		raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
 						       cpu);
 		struct cgroup *pos = NULL;
+		unsigned long flags;
 
-		raw_spin_lock(cpu_lock);
+		/*
+		 * The _irqsave() is needed because cgroup_rstat_lock is
+		 * spinlock_t which is a sleeping lock on PREEMPT_RT. Acquiring
+		 * this lock with the _irq() suffix only disables interrupts on
+		 * a non-PREEMPT_RT kernel. The raw_spinlock_t below disables
+		 * interrupts on both configurations. The _irqsave() ensures
+		 * that interrupts are always disabled and later restored.
+		 */
+		raw_spin_lock_irqsave(cpu_lock, flags);
 		while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
 			struct cgroup_subsys_state *css;
 
@@ -166,7 +175,7 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
 				css->ss->css_rstat_flush(css, cpu);
 			rcu_read_unlock();
 		}
-		raw_spin_unlock(cpu_lock);
+		raw_spin_unlock_irqrestore(cpu_lock, flags);
 
 		/* if @may_sleep, play nice and yield if necessary */
 		if (may_sleep && (need_resched() ||
diff --git a/kernel/kcov.c b/kernel/kcov.c
index 36ca640c4f8e..475524bd900a 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -459,37 +459,28 @@ void kcov_task_exit(struct task_struct *t)
 static int kcov_mmap(struct file *filep, struct vm_area_struct *vma)
 {
 	int res = 0;
-	void *area;
 	struct kcov *kcov = vma->vm_file->private_data;
 	unsigned long size, off;
 	struct page *page;
 	unsigned long flags;
 
-	area = vmalloc_user(vma->vm_end - vma->vm_start);
-	if (!area)
-		return -ENOMEM;
-
 	spin_lock_irqsave(&kcov->lock, flags);
 	size = kcov->size * sizeof(unsigned long);
-	if (kcov->mode != KCOV_MODE_INIT || vma->vm_pgoff != 0 ||
+	if (kcov->area == NULL || vma->vm_pgoff != 0 ||
 	    vma->vm_end - vma->vm_start != size) {
 		res = -EINVAL;
 		goto exit;
 	}
-	if (!kcov->area) {
-		kcov->area = area;
-		vma->vm_flags |= VM_DONTEXPAND;
-		spin_unlock_irqrestore(&kcov->lock, flags);
-		for (off = 0; off < size; off += PAGE_SIZE) {
-			page = vmalloc_to_page(kcov->area + off);
-			if (vm_insert_page(vma, vma->vm_start + off, page))
-				WARN_ONCE(1, "vm_insert_page() failed");
-		}
-		return 0;
+	spin_unlock_irqrestore(&kcov->lock, flags);
+	vma->vm_flags |= VM_DONTEXPAND;
+	for (off = 0; off < size; off += PAGE_SIZE) {
+		page = vmalloc_to_page(kcov->area + off);
+		if (vm_insert_page(vma, vma->vm_start + off, page))
+			WARN_ONCE(1, "vm_insert_page() failed");
 	}
+	return 0;
 exit:
 	spin_unlock_irqrestore(&kcov->lock, flags);
-	vfree(area);
 	return res;
 }
 
@@ -564,31 +555,12 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
 			     unsigned long arg)
 {
 	struct task_struct *t;
-	unsigned long size, unused;
+	unsigned long flags, unused;
 	int mode, i;
 	struct kcov_remote_arg *remote_arg;
 	struct kcov_remote *remote;
-	unsigned long flags;
 
 	switch (cmd) {
-	case KCOV_INIT_TRACE:
-		/*
-		 * Enable kcov in trace mode and setup buffer size.
-		 * Must happen before anything else.