This is a note to let you know that I've just added the patch titled tick/nohz: unexport __init-annotated tick_nohz_full_setup() to the 5.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tick-nohz-unexport-__init-annotated-tick_nohz_full_setup.patch and it can be found in the queue-5.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 2390095113e98fc52fffe35c5206d30d9efe3f78 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada <masahiroy@xxxxxxxxxx> Date: Mon, 27 Jun 2022 12:22:09 +0900 Subject: tick/nohz: unexport __init-annotated tick_nohz_full_setup() From: Masahiro Yamada <masahiroy@xxxxxxxxxx> commit 2390095113e98fc52fffe35c5206d30d9efe3f78 upstream. EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic. modpost used to detect it, but it had been broken for a decade. Commit 28438794aba4 ("modpost: fix section mismatch check for exported init/exit sections") fixed it so modpost started to warn it again, then this showed up: MODPOST vmlinux.symvers WARNING: modpost: vmlinux.o(___ksymtab_gpl+tick_nohz_full_setup+0x0): Section mismatch in reference from the variable __ksymtab_tick_nohz_full_setup to the function .init.text:tick_nohz_full_setup() The symbol tick_nohz_full_setup is exported and annotated __init Fix this by removing the __init annotation of tick_nohz_full_setup or drop the export. Drop the export because tick_nohz_full_setup() is only called from the built-in code in kernel/sched/isolation.c. Fixes: ae9e557b5be2 ("time: Export tick start/stop functions for rcutorture") Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> Tested-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Backlund <tmb@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/time/tick-sched.c | 1 - 1 file changed, 1 deletion(-) --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -526,7 +526,6 @@ void __init tick_nohz_full_setup(cpumask cpumask_copy(tick_nohz_full_mask, cpumask); tick_nohz_full_running = true; } -EXPORT_SYMBOL_GPL(tick_nohz_full_setup); static int tick_nohz_cpu_down(unsigned int cpu) { Patches currently in stable-queue which might be from masahiroy@xxxxxxxxxx are queue-5.18/tick-nohz-unexport-__init-annotated-tick_nohz_full_setup.patch