[APL] igt@gem_ctx_persistence@engines-mixed-process@rcs0|igt@gem_eio@in-flight-1us - dmesg-warn - kernel/sched/core.c:.* Illegal context switch in RCU-bh read-side critical section!
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_842/fi-apl-guc/igt@gem_ctx_persistence@engines-mixed-process@rcs0.html
<4> [294.648638] =============================
<4> [294.648640] WARNING: suspicious RCU usage
<4> [294.648642] 5.13.0-rc6-g940478dea0bcc-drmtip_842+ #1 Tainted: G U
<4> [294.648647] ======================================================
<4> [294.648652] -----------------------------
<4> [294.648657] WARNING: possible circular locking dependency detected
<4> [294.648664] kernel/sched/core.c:8304 Illegal context switch in RCU-bh read-side critical section!
<4> [294.648672] 5.13.0-rc6-g940478dea0bcc-drmtip_842+ #1 Tainted: G U
<4> [294.648676]
other info that might help us debug this:
<4> [294.648682] ------------------------------------------------------
<4> [294.648691]
rcu_scheduler_active = 2, debug_locks = 0
<4> [294.648698] gem_ctx_persist/1220 is trying to acquire lock:
<4> [294.648706] 3 locks held by dmesg/913:
<4> [294.648713] ffffffff82645710
<4> [294.648720] #0:
<4> [294.648726] (
<4> [294.648731] ffff888107a935b0
<4> [294.648736] cpu_hotplug_lock
<4> [294.648741] (
<4> [294.648745] ){++++}-{0:0}
<4> [294.648750] &f->f_pos_lock
<4> [294.648755] , at: stop_machine+0x12/0x30
<4> [294.648763]
but task is already holding lock:
<4> [294.648767] ){+.+.}-{3:3}
<4> [294.648773] ffff88812fcebad8 (
<4> [294.648780] , at: __fdget_pos+0x45/0x50
<4> [294.648791] >->reset.mutex
<4> [294.648796] #1:
<4> [294.648797] ){+.+.}-{3:3}
<4> [294.648802] ffff888105101430 (sb_writers#3){.+.+}-{0:0}, at: ksys_write+0x5a/0xd0
<4> [294.648828] #2: ffff8881068ef860 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}, at: ext4_buffered_write_iter+0x37/0x160
<4> [294.648849]
stack backtrace:
<4> [294.648855] CPU: 2 PID: 913 Comm: dmesg Tainted: G U 5.13.0-rc6-g940478dea0bcc-drmtip_842+ #1
<4> [294.648867] Hardware name: Intel corporation NUC6CAYS/NUC6CAYB, BIOS AYAPLCEL.86A.0056.2018.0926.1100 09/26/2018
<4> [294.648879] Call Trace:
<4> [294.648885] dump_stack+0x7f/0xad
<4> [294.648894] ___might_sleep+0xfc/0x140
<4> [294.648903] pagecache_get_page+0x63c/0x710
<4> [294.648914] grab_cache_page_write_begin+0x17/0x30
<4> [294.648922] ext4_da_write_begin+0xde/0x4b0
<4> [294.648932] generic_perform_write+0xf2/0x1c0
<4> [294.648806] , at: intel_gt_reset+0x11a/0x340 [i915]
<4> [294.648942] ? file_update_time+0x59/0x110
<4> [294.648946] ext4_buffered_write_iter+0xa6/0x160
<4> [294.648950] ext4_file_write_iter+0x5a/0x840
<4> [294.648955] new_sync_write+0x11d/0x1b0
<4> [294.648961] vfs_write+0x265/0x390
<4> [294.648965] ksys_write+0x5a/0xd0
<4> [294.648970] do_syscall_64+0x3c/0xb0
<4> [294.648974] entry_SYSCALL_64_after_hwframe+0x44/0xae
<4> [294.648979] RIP: 0033:0x7f7f27aec154
<4> [294.648983] Code: 89 02 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8d 05 b1 07 2e 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 41 54 55 49 89 d4 53 48 89 f5
<4> [294.648986] RSP: 002b:00007ffd41b4bc98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
<4> [294.648990] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f7f27aec154
<4> [294.648993] RDX: 0000000000000001 RSI: 00007f7f27dc87e3 RDI: 0000000000000001
<4> [294.648995] RBP: 00007f7f27dc87e3 R08: 0000000000000000 R09: 0000000000000000
<4> [294.648996] R10: 0000000000000002 R11: 0000000000000246 R12: 00007f7f27dc8760
<4> [294.648998] R13: 0000000000000001 R14: 00007f7f27dc42a0 R15: 00007f7f27dc3760
<4> [294.649135]
which lock already depends on the new lock.
<4> [294.649143]
the existing dependency chain (in reverse order) is:
<4> [294.649152]
-> #2 (>->reset.mutex){+.+.}-{3:3}:
<4> [294.649164] i915_gem_shrinker_taints_mutex+0x2d/0x50 [i915]
<4> [294.649397] intel_gt_init_reset+0x61/0x80 [i915]
<4> [294.649637] intel_gt_init_early+0xe6/0x120 [i915]
<4> [294.649891] i915_driver_probe+0x328/0xdb0 [i915]
<4> [294.650110] i915_pci_probe+0x43/0x1d0 [i915]
<4> [294.650308] pci_device_probe+0x9e/0x110
<4> [294.650319] really_probe+0xea/0x3e0
<4> [294.650327] driver_probe_device+0xe0/0x150
<4> [294.650334] device_driver_attach+0x4a/0x50
<4> [294.650341] __driver_attach+0x8a/0x150
<4> [294.650348] bus_for_each_dev+0x75/0xc0
<4> [294.650355] bus_add_driver+0x14b/0x1f0
<4> [294.650362] driver_register+0x66/0xb0
<4> [294.650368] 0xffffffffa0707070
<4> [294.650374] do_one_initcall+0x56/0x2e0
<4> [294.650383] do_init_module+0x55/0x200
<4> [294.650391] load_module+0x2703/0x2990
<4> [294.650398] __do_sys_finit_module+0xad/0x110
<4> [294.650406] do_syscall_64+0x3c/0xb0
<4> [294.650414] entry_SYSCALL_64_after_hwframe+0x44/0xae
<4> [294.650423]
-> #1 (fs_reclaim){+.+.}-{0:0}:
<4> [294.650435] fs_reclaim_acquire+0x9f/0xd0
<4> [294.650445] kmem_cache_alloc_trace+0x2f/0x7f0
<4> [294.650453] intel_cpuc_prepare+0x40/0x1b0
<4> [294.650461] cpuhp_invoke_callback+0x189/0x870
<4> [294.650470] cpuhp_invoke_callback_range+0x3b/0x80
<4> [294.650478] _cpu_up+0xd1/0x1c0
<4> [294.650485] cpu_up+0x82/0x90
<4> [294.650491] bringup_nonboot_cpus+0x4a/0x60
<4> [294.650499] smp_init+0x21/0x5c
<4> [294.650507] kernel_init_freeable+0xbe/0x1f0
<4> [294.650515] kernel_init+0x5/0xff
<4> [294.650522] ret_from_fork+0x22/0x30
<4> [294.650529]
-> #0 (cpu_hotplug_lock){++++}-{0:0}:
<4> [294.650540] __lock_acquire+0x151e/0x2590
<4> [294.650549] lock_acquire+0xd1/0x3d0
<4> [294.650555] cpus_read_lock+0x39/0xc0
<4> [294.650562] stop_machine+0x12/0x30
<4> [294.650569] bxt_vtd_ggtt_insert_entries__BKL+0x36/0x50 [i915]
<4> [294.650787] uc_fw_bind_ggtt+0xc6/0x100 [i915]
<4> [294.651028] intel_uc_fw_upload+0x85/0x330 [i915]
<4> [294.651268] __uc_init_hw+0x1b3/0x5a0 [i915]
<4> [294.651521] intel_gt_init_hw+0xe3/0x240 [i915]
<4> [294.651734] intel_gt_reset+0x2e2/0x340 [i915]
<4> [294.651948] intel_gt_reset_global+0xf7/0x170 [i915]
<4> [294.652163] intel_gt_handle_error+0x18a/0x380 [i915]
<4> [294.652379] i915_drop_caches_set+0x159/0x270 [i915]
<4> [294.652573] simple_attr_write+0xd9/0x100
<4> [294.652582] full_proxy_write+0x51/0x80
<4> [294.652590] vfs_write+0xc4/0x390
<4> [294.652598] ksys_write+0x5a/0xd0
<4> [294.652605] do_syscall_64+0x3c/0xb0
<4> [294.652613] entry_SYSCALL_64_after_hwframe+0x44/0xae