From: Zhang Jianhua <chris.zjh@huawei.com>
To: <ardb@kernel.org>
Cc: <linux-efi@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH -next] efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock()
Date: Thu, 23 Sep 2021 10:53:40 +0800 [thread overview]
Message-ID: <20210923025340.1469836-1-chris.zjh@huawei.com> (raw)
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>
---
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 1410beaef5c3..f3e54f6616f0 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -414,7 +414,7 @@ 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;
--
2.31.0
next reply other threads:[~2021-09-23 2:51 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 2:53 Zhang Jianhua [this message]
2021-10-05 11:08 ` [PATCH -next] efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock() Ard Biesheuvel
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