Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
   ("refactor Kconfig to consolidate KEXEC and CRASH options")

 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h")

 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands")

 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions")

 - Switch the handling of kdump from a udev scheme to in-kernel
   handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
   hot un/plug")

 - Many singleton patches to various parts of the tree

* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
  document while_each_thread(), change first_tid() to use for_each_thread()
  drivers/char/mem.c: shrink character device's devlist[] array
  x86/crash: optimize CPU changes
  crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
  crash: hotplug support for kexec_load()
  x86/crash: add x86 crash hotplug support
  crash: memory and CPU hotplug sysfs attributes
  kexec: exclude elfcorehdr from the segment digest
  crash: add generic infrastructure for crash hotplug support
  crash: move a few code bits to setup support of crash hotplug
  kstrtox: consistently use _tolower()
  kill do_each_thread()
  nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
  scripts/bloat-o-meter: count weak symbol sizes
  treewide: drop CONFIG_EMBEDDED
  lockdep: fix static memory detection even more
  lib/vsprintf: declare no_hash_pointers in sprintf.h
  lib/vsprintf: split out sprintf() and friends
  kernel/fork: stop playing lockless games for exe_file replacement
  adfs: delete unused "union adfs_dirtail" definition
  ...

Author: torvalds

Documentation/ABI/testing/sysfs-devices-memory

@@ -110,3 +110,11 @@ Description:
 		link is created for memory section 9 on node0.
 
 		/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
+
+What:		/sys/devices/system/memory/crash_hotplug
+Date:		Aug 2023
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RO) indicates whether or not the kernel directly supports
+		modifying the crash elfcorehdr for memory hot un/plug and/or
+		on/offline changes.

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -688,3 +688,11 @@ Description:
 		(RO) the list of CPUs that are isolated and don't
 		participate in load balancing. These CPUs are set by
 		boot parameter "isolcpus=".
+
+What:		/sys/devices/system/cpu/crash_hotplug
+Date:		Aug 2023
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		(RO) indicates whether or not the kernel directly supports
+		modifying the crash elfcorehdr for CPU hot un/plug and/or
+		on/offline changes.

Documentation/admin-guide/mm/memory-hotplug.rst

@@ -291,6 +291,14 @@ The following files are currently defined:
 		       Availability depends on the CONFIG_ARCH_MEMORY_PROBE
 		       kernel configuration option.
 ``uevent``	       read-write: generic udev file for device subsystems.
+``crash_hotplug``      read-only: when changes to the system memory map
+		       occur due to hot un/plug of memory, this file contains
+		       '1' if the kernel updates the kdump capture kernel memory
+		       map itself (via elfcorehdr), or '0' if userspace must update
+		       the kdump capture kernel memory map.
+
+		       Availability depends on the CONFIG_MEMORY_HOTPLUG kernel
+		       configuration option.
 ====================== =========================================================
 
 .. note::

Documentation/core-api/cpu_hotplug.rst

@@ -741,6 +741,24 @@ will receive all events. A script like::
 
 can process the event further.
 
+When changes to the CPUs in the system occur, the sysfs file
+/sys/devices/system/cpu/crash_hotplug contains '1' if the kernel
+updates the kdump capture kernel list of CPUs itself (via elfcorehdr),
+or '0' if userspace must update the kdump capture kernel list of CPUs.
+
+The availability depends on the CONFIG_HOTPLUG_CPU kernel configuration
+option.
+
+To skip userspace processing of CPU hot un/plug events for kdump
+(i.e. the unload-then-reload to obtain a current list of CPUs), this sysfs
+file can be used in a udev rule as follows:
+
+ SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
+
+For a CPU hot un/plug event, if the architecture supports kernel updates
+of the elfcorehdr (which contains the list of CPUs), then the rule skips
+the unload-then-reload of the kdump capture kernel.
+
 Kernel Inline Documentations Reference
 ======================================
 

arch/Kconfig

@@ -11,19 +11,6 @@ source "arch/$(SRCARCH)/Kconfig"
 
 menu "General architecture-dependent options"
 
-config CRASH_CORE
-	bool
-
-config KEXEC_CORE
-	select CRASH_CORE
-	bool
-
-config KEXEC_ELF
-	bool
-
-config HAVE_IMA_KEXEC
-	bool
-
 config ARCH_HAS_SUBPAGE_FAULTS
 	bool
 	help
@@ -748,7 +735,9 @@ config HAS_LTO_CLANG
 	depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
 	depends on ARCH_SUPPORTS_LTO_CLANG
 	depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
-	depends on !KASAN || KASAN_HW_TAGS
+	# https://github.com/ClangBuiltLinux/linux/issues/1721
+	depends on (!KASAN || KASAN_HW_TAGS || CLANG_VERSION >= 170000) || !DEBUG_INFO
+	depends on (!KCOV || CLANG_VERSION >= 170000) || !DEBUG_INFO
 	depends on !GCOV_KERNEL
 	help
 	  The compiler and Kconfig options support building with Clang's

arch/arc/configs/axs101_defconfig

@@ -9,7 +9,7 @@ CONFIG_NAMESPACES=y
 # CONFIG_UTS_NS is not set
 # CONFIG_PID_NS is not set
 CONFIG_BLK_DEV_INITRD=y
-CONFIG_EMBEDDED=y
+CONFIG_EXPERT=y
 CONFIG_PERF_EVENTS=y
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_SLUB_DEBUG is not set

arch/arc/configs/axs103_defconfig

@@ -9,7 +9,7 @@ CONFIG_NAMESPACES=y
 # CONFIG_UTS_NS is not set
 # CONFIG_PID_NS is not set
 CONFIG_BLK_DEV_INITRD=y
-CONFIG_EMBEDDED=y
+CONFIG_EXPERT=y
 CONFIG_PERF_EVENTS=y
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_SLUB_DEBUG is not set

arch/arc/configs/axs103_smp_defconfig

@@ -9,7 +9,7 @@ CONFIG_NAMESPACES=y
 # CONFIG_UTS_NS is not set
 # CONFIG_PID_NS is not set
 CONFIG_BLK_DEV_INITRD=y
-CONFIG_EMBEDDED=y
+CONFIG_EXPERT=y
 CONFIG_PERF_EVENTS=y
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_COMPAT_BRK is not set

arch/arc/configs/haps_hs_smp_defconfig

@@ -11,7 +11,7 @@ CONFIG_NAMESPACES=y
 # CONFIG_UTS_NS is not set
 # CONFIG_PID_NS is not set
 CONFIG_BLK_DEV_INITRD=y
-CONFIG_EMBEDDED=y
+CONFIG_EXPERT=y
 CONFIG_PERF_EVENTS=y
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_COMPAT_BRK is not set

arch/arc/configs/hsdk_defconfig

@@ -9,7 +9,7 @@ CONFIG_NAMESPACES=y
 # CONFIG_PID_NS is not set
 CONFIG_BLK_DEV_INITRD=y
 CONFIG_BLK_DEV_RAM=y
-CONFIG_EMBEDDED=y
+CONFIG_EXPERT=y
 CONFIG_PERF_EVENTS=y
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_COMPAT_BRK is not set