During kexec, it is possible for userspace to race with
device_shutdown() causing accesses to GPU after pm_runtime suspend has
already happened. Fix by freezing userspace 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
[ 292.534467] el0_svc_common+0x98/0x104
[ 292.534473] do_el0_svc+0x30/0x80
[ 292.534478] el0_svc+0x20/0x50
[ 292.534481] el0t_64_sync_handler+0x78/0x108
[ 292.534485] el0t_64_sync+0x1a4/0x1a8
[ 292.534632] Kernel Offset: 0x1a5f800000 from 0xffffffc008000000
[ 292.534635] PHYS_OFFSET: 0x80000000
[ 292.534638] CPU features: 0x40018541,a3300e42
[ 292.534644] Memory Limit: none
Cc: rostedt@xxxxxxxxxxx
Cc: ribalda@xxxxxxxxxx
Cc: zwisler@xxxxxxxxxx
Cc: robdclark@xxxxxxxxx
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 ca2743f9c634..2614a7f1f8a6 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1175,6 +1175,12 @@ 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();
--
2.38.1.584.g0f3c55d4c2-goog
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