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12e89c21de
Following locking sequence leads to deadlock:
1. gk20a_pm_prepare_poweroff (alter_usermode_mappings):
ctrl_privs_lock -> mmap_lock
2. __do_munmap (usermode_vma_close):
mmap_lock -> ctrl_privs_lock
This lock contention can be resolved by retrying the usermode mapping
alteration after a while releasing the ctrl_priv_lock for munmap to
proceed.
Below is the kernel panic log with deadlock.
[] INFO: task kworker/1:1:116 blocked for more than 120 seconds.
[] Tainted: G W 5.10.17-tegra #1
[] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[] task:kworker/1:1 state:D stack: 0 pid: 116 ppid: 2 flags:0x00000028
[] Workqueue: pm pm_runtime_work
[] Call trace:
[] __switch_to+0x104/0x160
[] __schedule+0x3d4/0x900
[] schedule+0x74/0x100
[] rwsem_down_write_slowpath+0x250/0x4b0
[] down_write+0x6c/0x80
[] alter_usermode_mappings+0xb4/0x160 [nvgpu]
[] nvgpu_hide_usermode_for_poweroff+0x24/0x30 [nvgpu]
[] gk20a_pm_prepare_poweroff+0xe8/0x140 [nvgpu]
[] gk20a_pm_runtime_suspend+0x78/0xf0 [nvgpu]
[] pm_generic_runtime_suspend+0x3c/0x60
[] genpd_runtime_suspend+0xb0/0x2c0
[] __rpm_callback+0x90/0x150
[] rpm_callback+0x34/0xa0
[] rpm_suspend+0xe0/0x5e0
[] pm_runtime_work+0xbc/0xc0
[] process_one_work+0x1c0/0x4a0
[] worker_thread+0x11c/0x430
[] kthread+0x148/0x170
[] ret_from_fork+0x10/0x18
[] INFO: task nvrm_gpu_tests:1273 blocked for more than 121 seconds.
[] Tainted: G W 5.10.17-tegra #1
[] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[] task:nvrm_gpu_tests state:D stack: 0 pid: 1273 ppid: 1245 flags:0x00000000
[] Call trace:
[] __switch_to+0x104/0x160
[] __schedule+0x3d4/0x900
[] schedule+0x74/0x100
[] schedule_preempt_disabled+0x28/0x40
[] __mutex_lock.isra.0+0x184/0x5c0
[] __mutex_lock_slowpath+0x24/0x30
[] mutex_lock+0x5c/0x70
[] usermode_vma_close+0x30/0x50 [nvgpu]
[] remove_vma+0x34/0x60
[] __do_munmap+0x1f4/0x4a0
[] __vm_munmap+0x74/0xd0
[] __arm64_sys_munmap+0x3c/0x50
[] el0_svc_common.constprop.0+0x7c/0x1a0
[] do_el0_svc+0x34/0xa0
[] el0_svc+0x1c/0x30
[] el0_sync_handler+0xa8/0xb0
[] el0_sync+0x160/0x180
[] ---[ end Kernel panic - not syncing: hung_task: blocked tasks ]---
Bug 200703921
Change-Id: Ie7f017c92f20061d3bf891079f7fc7fe390f7cf7
Signed-off-by: Sagar Kamble <skamble@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2533853
(cherry picked from commit 1dd3e0761c)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2540111
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>