Commit 119f6bce authored Feb 01, 2023 by Tiezhu Yang Committed by Greg Kroah-Hartman Feb 06, 2023

panic: unset panic_on_warn inside panic()

commit 1a2383e8b84c0451fd9b1eec3b9aab16f30b597c upstream.

In the current code, the following three places need to unset
panic_on_warn before calling panic() to avoid recursive panics:

kernel/kcsan/report.c: print_report()
kernel/sched/core.c: __schedule_bug()
mm/kfence/report.c: kfence_report_error()

In order to avoid copy-pasting "panic_on_warn = 0" all over the places,
it is better to move it inside panic() and then remove it from the other
places.

Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loongson.cn


Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent f6c20ed1

kernel/panic.c

+11 −9

Original line number	Diff line number	Diff line
		@@ -173,6 +173,16 @@ void panic(const char *fmt, ...)
		int old_cpu, this_cpu;
		bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;

		if (panic_on_warn) {
		/*
		* This thread may hit another WARN() in the panic path.
		* Resetting this prevents additional WARN() from panicking the
		* system on this thread. Other threads are blocked by the
		* panic_mutex in panic().
		*/
		panic_on_warn = 0;
		}

		/*
		* Disable local interrupts. This will prevent panic_smp_self_stop
		* from deadlocking the first cpu that invokes the panic, since
		@@ -571,16 +581,8 @@ void __warn(const char file, int line, void caller, unsigned taint,
		if (args)
		vprintk(args->fmt, args->args);

		if (panic_on_warn) {
		/*
		* This thread may hit another WARN() in the panic path.
		* Resetting this prevents additional WARN() from panicking the
		* system on this thread. Other threads are blocked by the
		* panic_mutex in panic().
		*/
		panic_on_warn = 0;
		if (panic_on_warn)
		panic("panic_on_warn set ...\n");
		}

		print_modules();