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/9ecfdee7dd4d741d172cb93ff1d87f1c58127c9a.1633001016.git.christophe.leroy@xxxxxxxxxx Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxxx> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> 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 @@ -1506,6 +1506,8 @@ 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; _
