[PATCH] kexec: Fix reboot race during device_shutdown()
From: Joel Fernandes (Google)
Date: Thu Sep 28 2023 - 22:12:22 EST
During kexec reboot, it is possible for a race to occur between
device_shutdown() and userspace. This causes accesses to GPU after pm_runtime
suspend has already happened. Fix this by calling freeze_processes() before
device_shutdown().
Such freezing is already being done if kernel supports KEXEC_JUMP and
kexec_image->preserve_context is true. However, doing it if either of these are
not true prevents crashes/races.
This fixes the following crash during kexec reboot on an ARM64 device
with adreno GPU:
[ 292.534314] Kernel panic - not syncing: Asynchronous SError Interrupt
[ 292.534323] Hardware name: Google Lazor (rev3 - 8) with LTE (DT)
[ 292.534326] Call trace:
[ 292.534328] dump_backtrace+0x0/0x1d4
[ 292.534337] show_stack+0x20/0x2c
[ 292.534342] dump_stack_lvl+0x60/0x78
[ 292.534347] dump_stack+0x18/0x38
[ 292.534352] panic+0x148/0x3b0
[ 292.534357] nmi_panic+0x80/0x94
[ 292.534364] arm64_serror_panic+0x70/0x7c
[ 292.534369] do_serror+0x0/0x7c
[ 292.534372] do_serror+0x54/0x7c
[ 292.534377] el1h_64_error_handler+0x34/0x4c
[ 292.534381] el1h_64_error+0x7c/0x80
[ 292.534386] el1_interrupt+0x20/0x58
[ 292.534389] el1h_64_irq_handler+0x18/0x24
[ 292.534395] el1h_64_irq+0x7c/0x80
[ 292.534399] local_daif_inherit+0x10/0x18
[ 292.534405] el1h_64_sync_handler+0x48/0xb4
[ 292.534410] el1h_64_sync+0x7c/0x80
[ 292.534414] a6xx_gmu_set_oob+0xbc/0x1fc
[ 292.534422] a6xx_get_timestamp+0x40/0xb4
[ 292.534426] adreno_get_param+0x12c/0x1e0
[ 292.534433] msm_ioctl_get_param+0x64/0x70
[ 292.534440] drm_ioctl_kernel+0xe8/0x158
[ 292.534448] drm_ioctl+0x208/0x320
[ 292.534453] __arm64_sys_ioctl+0x98/0xd0
[ 292.534461] invoke_syscall+0x4c/0x118
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ricardo Ribalda <ribalda@xxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Ricardo Ribalda <ribalda@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
kernel/kexec_core.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index e2f2574d8b74..6599f485e42d 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1299,6 +1299,12 @@ int kernel_kexec(void)
} else
#endif
{
+ error = freeze_processes();
+ if (error) {
+ error = -EBUSY;
+ goto Unlock;
+ }
+
kexec_in_progress = true;
kernel_restart_prepare("kexec reboot");
migrate_to_reboot_cpu();
--
2.42.0.582.g8ccd20d70d-goog