From: Masahiro Yamada masahiroy@kernel.org
stable inclusion from stable-v5.10.128 commit c4ff3ffe0138234774602152fe67e3a898c615c6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5YM2H
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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@linux-foundation.org Signed-off-by: Masahiro Yamada masahiroy@kernel.org Tested-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: Thomas Backlund tmb@tmb.nu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- kernel/time/tick-sched.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index d0440f5d5b45..33750db5b564 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -486,7 +486,6 @@ void __init tick_nohz_full_setup(cpumask_var_t 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) {