From: Conor Dooley conor.dooley@microchip.com

Guenter reported a lockdep splat that appears to have been present for a while in v6.1.y & the backports of the riscv_patch_in_stop_machine dance did nothing to help here, as the lock is not being taken when patch_text_nosync() is called in riscv_cpufeature_patch_func(). Add the lock/unlock; elide the splat.

Fixes: c15ac4fd60d5 ("riscv/ftrace: Add dynamic function tracer support") Reported-by: Guenter Roeck linux@roeck-us.net cc: stable@vger.kernel.org Signed-off-by: Conor Dooley conor.dooley@microchip.com --- arch/riscv/kernel/cpufeature.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 694267d1fe81..fd1238df6149 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -9,6 +9,7 @@ #include <linux/bitmap.h> #include <linux/ctype.h> #include <linux/libfdt.h> +#include <linux/memory.h> #include <linux/module.h> #include <linux/of.h> #include <asm/alternative.h> @@ -316,8 +317,11 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin, }

tmp = (1U << alt->errata_id); - if (cpu_req_feature & tmp) + if (cpu_req_feature & tmp) { + mutex_lock(&text_mutex); patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len); + mutex_unlock(&text_mutex); + } } } #endif