The patch titled
Subject: mm: create a new system state and fix core_kernel_text()
has been added to the -mm tree. Its filename is
mm-create-a-new-system-state-and-fix-core_kernel_text.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-create-a-new-system-state-and-fix-core_kernel_text.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-create-a-new-system-state-and-fix-core_kernel_text.patch
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------------------------------------------------------
From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Subject: mm: create a new system state and fix core_kernel_text()
core_kernel_text() considers that until system_state in at least
SYSTEM_RUNNING, init memory is valid.
But init memory is freed a few lines before setting SYSTEM_RUNNING, so we
have a small period of time when core_kernel_text() is wrong.
Create an intermediate system state called SYSTEM_FREEING_INIT that is set
before starting freeing init memory, and use it in core_kernel_text() to
report init memory invalid earlier.
Link: https://lkml.kernel.org/r/ffa99e8e91e756b081427b27e408f275b7d43df7.1632813331.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kernel.h | 1 +
init/main.c | 2 ++
kernel/extable.c | 2 +-
3 files changed, 4 insertions(+), 1 deletion(-)
--- a/include/linux/kernel.h~mm-create-a-new-system-state-and-fix-core_kernel_text
+++ a/include/linux/kernel.h
@@ -248,6 +248,7 @@ extern bool early_boot_irqs_disabled;
extern enum system_states {
SYSTEM_BOOTING,
SYSTEM_SCHEDULING,
+ SYSTEM_FREEING_INITMEM,
SYSTEM_RUNNING,
SYSTEM_HALT,
SYSTEM_POWER_OFF,
--- a/init/main.c~mm-create-a-new-system-state-and-fix-core_kernel_text
+++ a/init/main.c
@@ -1505,6 +1505,8 @@ static int __ref kernel_init(void *unuse
kernel_init_freeable();
/* need to finish all async __init code before freeing the memory */
async_synchronize_full();
+
+ system_state = SYSTEM_FREEING_INITMEM;
kprobe_free_init_mem();
ftrace_free_init_mem();
kgdb_free_init_mem();
--- a/kernel/extable.c~mm-create-a-new-system-state-and-fix-core_kernel_text
+++ a/kernel/extable.c
@@ -76,7 +76,7 @@ int notrace core_kernel_text(unsigned lo
addr < (unsigned long)_etext)
return 1;
- if (system_state < SYSTEM_RUNNING &&
+ if (system_state < SYSTEM_FREEING_INITMEM &&
init_kernel_text(addr))
return 1;
return 0;
_
Patches currently in -mm which might be from christophe.leroy@xxxxxxxxxx are
mm-create-a-new-system-state-and-fix-core_kernel_text.patch
mm-make-generic-arch_is_kernel_initmem_freed-do-what-it-says.patch
powerpc-use-generic-version-of-arch_is_kernel_initmem_freed.patch
s390-use-generic-version-of-arch_is_kernel_initmem_freed.patch
