From: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> Subject: panic: unset panic_on_warn inside panic() 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@xxxxxxxxxxx Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Xuefeng Li <lixuefeng@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/panic.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) --- a/kernel/panic.c~panic-unset-panic_on_warn-inside-panic +++ a/kernel/panic.c @@ -185,6 +185,16 @@ 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 @@ -576,16 +586,8 @@ void __warn(const char *file, int line, if (regs) show_regs(regs); - 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"); - } if (!regs) dump_stack(); _
