From: Zhang Jianhua <chris.zjh@huawei.com> hulk inclusion category: bugfix bugzilla: 182892, https://gitee.com/openeuler/kernel/issues/I4F04R -------- While reboot the system by sysrq, the following bug will be occur. BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:90 in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 10052, name: rc.shutdown CPU: 3 PID: 10052 Comm: rc.shutdown Tainted: G W O 5.10.0 #1 Call trace: dump_backtrace+0x0/0x1c8 show_stack+0x18/0x28 dump_stack+0xd0/0x110 ___might_sleep+0x14c/0x160 __might_sleep+0x74/0x88 down_interruptible+0x40/0x118 virt_efi_reset_system+0x3c/0xd0 efi_reboot+0xd4/0x11c machine_restart+0x60/0x9c emergency_restart+0x1c/0x2c sysrq_handle_reboot+0x1c/0x2c __handle_sysrq+0xd0/0x194 write_sysrq_trigger+0xbc/0xe4 proc_reg_write+0xd4/0xf0 vfs_write+0xa8/0x148 ksys_write+0x6c/0xd8 __arm64_sys_write+0x18/0x28 el0_svc_common.constprop.3+0xe4/0x16c do_el0_svc+0x1c/0x2c el0_svc+0x20/0x30 el0_sync_handler+0x80/0x17c el0_sync+0x158/0x180 The reason for this problem is that irq has been disabled in machine_restart() and then it calls down_interruptible() in virt_efi_reset_system(), which would occur sleep in irq context, it is dangerous! Commit 99409b935c9a("locking/semaphore: Add might_sleep() to down_*() family") add might_sleep() in down_interruptible(), so the bug info is here. down_trylock() can solve this problem, cause there is no might_sleep. Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com> Reviewed-by: Chen Lifu <chenlifu@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Reviewed-by: Liao Chang <liaochang1@huawei.com> Reviewed-by: He Ying <heying24@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> Reviewed-by: Yihang Xu <xuyihang@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/firmware/efi/runtime-wrappers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c index 04288719721fc..ecee810f7a6fa 100644 --- a/drivers/firmware/efi/runtime-wrappers.c +++ b/drivers/firmware/efi/runtime-wrappers.c @@ -408,7 +408,7 @@ static void virt_efi_reset_system(int reset_type, unsigned long data_size, efi_char16_t *data) { - if (down_interruptible(&efi_runtime_lock)) { + if (down_trylock(&efi_runtime_lock)) { pr_warn("failed to invoke the reset_system() runtime service:\n" "could not get exclusive access to the firmware\n"); return; -- 2.25.1