* [PATCH] drm/vgem-fence: Fix potential deadlock on release
@ 2025-09-26 15:26 Janusz Krzysztofik
2025-09-28 14:00 ` Christian König
0 siblings, 1 reply; 4+ messages in thread
From: Janusz Krzysztofik @ 2025-09-26 15:26 UTC (permalink / raw)
To: dri-devel
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, Christian König, Chris Wilson,
Janusz Krzysztofik
A timer that expires a vgem fence automatically in 10 seconds is now
released with timer_delete_sync() from fence->ops.release() called on last
dma_fence_put(). In some scenarios, it can run in IRQ context, which is
not safe unless TIMER_IRQSAFE is used. One potentially risky scenario was
demonstrated in Intel DRM CI trybot, BAT run on machine bat-adlp-6, while
working on new IGT subtests syncobj_timeline@stress-* as user space
replacements of some problematic test cases of a dma-fence-chain selftest
[1].
[117.004338] ================================
[117.004340] WARNING: inconsistent lock state
[117.004342] 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 Tainted: G S U
[117.004346] --------------------------------
[117.004347] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
[117.004349] swapper/0/0 [HC1[1]:SC1[1]:HE0:SE0] takes:
[117.004352] ffff888138f86aa8 ((&fence->timer)){?.-.}-{0:0}, at: __timer_delete_sync+0x4b/0x190
[117.004361] {HARDIRQ-ON-W} state was registered at:
[117.004363] lock_acquire+0xc4/0x2e0
[117.004366] call_timer_fn+0x80/0x2a0
[117.004368] __run_timers+0x231/0x310
[117.004370] run_timer_softirq+0x76/0xe0
[117.004372] handle_softirqs+0xd4/0x4d0
[117.004375] __irq_exit_rcu+0x13f/0x160
[117.004377] irq_exit_rcu+0xe/0x20
[117.004379] sysvec_apic_timer_interrupt+0xa0/0xc0
[117.004382] asm_sysvec_apic_timer_interrupt+0x1b/0x20
[117.004385] cpuidle_enter_state+0x12b/0x8a0
[117.004388] cpuidle_enter+0x2e/0x50
[117.004393] call_cpuidle+0x22/0x60
[117.004395] do_idle+0x1fd/0x260
[117.004398] cpu_startup_entry+0x29/0x30
[117.004401] start_secondary+0x12d/0x160
[117.004404] common_startup_64+0x13e/0x141
[117.004407] irq event stamp: 2282669
[117.004409] hardirqs last enabled at (2282668): [<ffffffff8289db71>] _raw_spin_unlock_irqrestore+0x51/0x80
[117.004414] hardirqs last disabled at (2282669): [<ffffffff82882021>] sysvec_irq_work+0x11/0xc0
[117.004419] softirqs last enabled at (2254702): [<ffffffff8289fd00>] __do_softirq+0x10/0x18
[117.004423] softirqs last disabled at (2254725): [<ffffffff813d4ddf>] __irq_exit_rcu+0x13f/0x160
[117.004426]
other info that might help us debug this:
[117.004429] Possible unsafe locking scenario:
[117.004432] CPU0
[117.004433] ----
[117.004434] lock((&fence->timer));
[117.004436] <Interrupt>
[117.004438] lock((&fence->timer));
[117.004440]
*** DEADLOCK ***
[117.004443] 1 lock held by swapper/0/0:
[117.004445] #0: ffffc90000003d50 ((&fence->timer)){?.-.}-{0:0}, at: call_timer_fn+0x7a/0x2a0
[117.004450]
stack backtrace:
[117.004453] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G S U 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 PREEMPT(voluntary)
[117.004455] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
[117.004455] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
[117.004456] Call Trace:
[117.004456] <IRQ>
[117.004457] dump_stack_lvl+0x91/0xf0
[117.004460] dump_stack+0x10/0x20
[117.004461] print_usage_bug.part.0+0x260/0x360
[117.004463] mark_lock+0x76e/0x9c0
[117.004465] ? register_lock_class+0x48/0x4a0
[117.004467] __lock_acquire+0xbc3/0x2860
[117.004469] lock_acquire+0xc4/0x2e0
[117.004470] ? __timer_delete_sync+0x4b/0x190
[117.004472] ? __timer_delete_sync+0x4b/0x190
[117.004473] __timer_delete_sync+0x68/0x190
[117.004474] ? __timer_delete_sync+0x4b/0x190
[117.004475] timer_delete_sync+0x10/0x20
[117.004476] vgem_fence_release+0x19/0x30 [vgem]
[117.004478] dma_fence_release+0xc1/0x3b0
[117.004480] ? dma_fence_release+0xa1/0x3b0
[117.004481] dma_fence_chain_release+0xe7/0x130
[117.004483] dma_fence_release+0xc1/0x3b0
[117.004484] ? _raw_spin_unlock_irqrestore+0x27/0x80
[117.004485] dma_fence_chain_irq_work+0x59/0x80
[117.004487] irq_work_single+0x75/0xa0
[117.004490] irq_work_run_list+0x33/0x60
[117.004491] irq_work_run+0x18/0x40
[117.004493] __sysvec_irq_work+0x35/0x170
[117.004494] sysvec_irq_work+0x47/0xc0
[117.004496] asm_sysvec_irq_work+0x1b/0x20
[117.004497] RIP: 0010:_raw_spin_unlock_irqrestore+0x57/0x80
[117.004499] Code: 00 75 1c 65 ff 0d d9 34 68 01 74 20 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3 cc cc cc cc e8 7f 9d d3 fe fb 0f 1f 44 00 00 <eb> d7 0f 1f 44 00 00 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3
[117.004499] RSP: 0018:ffffc90000003cf0 EFLAGS: 00000246
[117.004500] RAX: 0000000000000000 RBX: ffff888155e94c40 RCX: 0000000000000000
[117.004501] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[117.004502] RBP: ffffc90000003d00 R08: 0000000000000000 R09: 0000000000000000
[117.004502] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000246
[117.004502] R13: 0000000000000001 R14: 0000000000000246 R15: ffff888155e94c80
[117.004506] dma_fence_signal+0x49/0xb0
[117.004507] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
[117.004508] vgem_fence_timeout+0x12/0x20 [vgem]
[117.004509] call_timer_fn+0xa1/0x2a0
[117.004512] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
[117.004513] __run_timers+0x231/0x310
[117.004514] ? tmigr_handle_remote+0x2ac/0x560
[117.004517] timer_expire_remote+0x46/0x70
[117.004518] tmigr_handle_remote+0x433/0x560
[117.004520] ? __run_timers+0x239/0x310
[117.004521] ? run_timer_softirq+0x21/0xe0
[117.004522] ? lock_release+0xce/0x2a0
[117.004524] run_timer_softirq+0xcf/0xe0
[117.004525] handle_softirqs+0xd4/0x4d0
[117.004526] __irq_exit_rcu+0x13f/0x160
[117.004527] irq_exit_rcu+0xe/0x20
[117.004528] sysvec_apic_timer_interrupt+0xa0/0xc0
[117.004529] </IRQ>
[117.004529] <TASK>
[117.004529] asm_sysvec_apic_timer_interrupt+0x1b/0x20
[117.004530] RIP: 0010:cpuidle_enter_state+0x12b/0x8a0
[117.004532] Code: 48 0f a3 05 97 ce 0e 01 0f 82 2e 03 00 00 31 ff e8 8a 41 bd fe 80 7d d0 00 0f 85 11 03 00 00 e8 8b 06 d5 fe fb 0f 1f 44 00 00 <45> 85 f6 0f 88 67 02 00 00 4d 63 ee 49 83 fd 0a 0f 83 34 06 00 00
[117.004532] RSP: 0018:ffffffff83403d88 EFLAGS: 00000246
[117.004533] RAX: 0000000000000000 RBX: ffff88888f046440 RCX: 0000000000000000
[117.004533] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[117.004534] RBP: ffffffff83403dd8 R08: 0000000000000000 R09: 0000000000000000
[117.004534] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff837cbe80
[117.004534] R13: 0000000000000004 R14: 0000000000000004 R15: 0000001ad1df466b
[117.004537] ? cpuidle_enter_state+0x125/0x8a0
[117.004538] ? sched_clock_noinstr+0x9/0x10
[117.004540] cpuidle_enter+0x2e/0x50
[117.004542] call_cpuidle+0x22/0x60
[117.004542] do_idle+0x1fd/0x260
[117.004544] cpu_startup_entry+0x29/0x30
[117.004546] rest_init+0x104/0x200
[117.004548] start_kernel+0x93d/0xbd0
[117.004550] ? load_ucode_intel_bsp+0x2a/0x90
[117.004551] ? sme_unmap_bootdata+0x14/0x80
[117.004554] x86_64_start_reservations+0x18/0x30
[117.004555] x86_64_start_kernel+0xfd/0x150
[117.004556] ? soft_restart_cpu+0x14/0x14
[117.004558] common_startup_64+0x13e/0x141
[117.004560] </TASK>
[117.004565] ------------[ cut here ]------------
[117.004692] WARNING: CPU: 0 PID: 0 at kernel/time/timer.c:1610 __timer_delete_sync+0x126/0x190
[117.004697] Modules linked in: vgem snd_hda_codec_intelhdmi snd_hda_codec_hdmi i915 prime_numbers ttm drm_buddy drm_display_helper cec rc_core i2c_algo_bit hid_sensor_custom hid_sensor_hub hid_generic intel_ishtp_hid hid intel_uncore_frequency intel_uncore_frequency_common x86_pkg_temp_thermal intel_powerclamp cmdlinepart ee1004 r8153_ecm spi_nor coretemp cdc_ether mei_pxp mei_hdcp usbnet mtd intel_rapl_msr wmi_bmof kvm_intel snd_hda_intel snd_intel_dspcfg processor_thermal_device_pci kvm snd_hda_codec processor_thermal_device irqbypass processor_thermal_wt_hint polyval_clmulni platform_temperature_control snd_hda_core ghash_clmulni_intel processor_thermal_rfim spi_pxa2xx_platform snd_hwdep aesni_intel processor_thermal_rapl dw_dmac snd_pcm dw_dmac_core intel_rapl_common r8152 rapl mii intel_cstate spi_pxa2xx_core i2c_i801 processor_thermal_wt_req snd_timer i2c_mux mei_me intel_ish_ipc processor_thermal_power_floor e1000e snd i2c_smbus spi_intel_pci processor_thermal_mbox mei soundcore intel_ishtp thunderbolt idma64
[117.004733] spi_intel int340x_thermal_zone igen6_edac binfmt_misc intel_skl_int3472_tps68470 intel_pmc_core tps68470_regulator video clk_tps68470 pmt_telemetry pmt_discovery nls_iso8859_1 pmt_class intel_pmc_ssram_telemetry intel_skl_int3472_discrete int3400_thermal intel_hid intel_skl_int3472_common acpi_thermal_rel intel_vsec wmi pinctrl_tigerlake acpi_tad sparse_keymap acpi_pad dm_multipath msr nvme_fabrics fuse efi_pstore nfnetlink autofs4
[117.004782] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G S U 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 PREEMPT(voluntary)
[117.004787] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
[117.004789] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
[117.004793] RIP: 0010:__timer_delete_sync+0x126/0x190
[117.004795] Code: 31 c0 45 31 c9 c3 cc cc cc cc 48 8b 75 d0 45 84 f6 74 63 49 c7 45 18 00 00 00 00 48 89 c7 e8 51 46 39 01 f3 90 e9 66 ff ff ff <0f> 0b e9 5f ff ff ff e8 ee e4 0c 00 49 8d 5d 28 45 31 c9 31 c9 4c
[117.004801] RSP: 0018:ffffc90000003a40 EFLAGS: 00010046
[117.004804] RAX: ffffffff815093fb RBX: ffff888138f86aa8 RCX: 0000000000000000
[117.004807] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[117.004809] RBP: ffffc90000003a70 R08: 0000000000000000 R09: 0000000000000000
[117.004812] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff815093fb
[117.004814] R13: ffff888138f86a80 R14: 0000000000000000 R15: 0000000000000000
[117.004817] FS: 0000000000000000(0000) GS:ffff88890b0f7000(0000) knlGS:0000000000000000
[117.004820] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[117.004823] CR2: 00005db8131eb7f0 CR3: 0000000003448000 CR4: 0000000000f52ef0
[117.004826] PKRU: 55555554
[117.004827] Call Trace:
[117.004829] <IRQ>
[117.004831] timer_delete_sync+0x10/0x20
[117.004833] vgem_fence_release+0x19/0x30 [vgem]
[117.004836] dma_fence_release+0xc1/0x3b0
[117.004838] ? dma_fence_release+0xa1/0x3b0
[117.004841] dma_fence_chain_release+0xe7/0x130
[117.004844] dma_fence_release+0xc1/0x3b0
[117.004847] ? _raw_spin_unlock_irqrestore+0x27/0x80
[117.004850] dma_fence_chain_irq_work+0x59/0x80
[117.004853] irq_work_single+0x75/0xa0
[117.004857] irq_work_run_list+0x33/0x60
[117.004860] irq_work_run+0x18/0x40
[117.004863] __sysvec_irq_work+0x35/0x170
[117.004865] sysvec_irq_work+0x47/0xc0
[117.004868] asm_sysvec_irq_work+0x1b/0x20
[117.004871] RIP: 0010:_raw_spin_unlock_irqrestore+0x57/0x80
[117.004874] Code: 00 75 1c 65 ff 0d d9 34 68 01 74 20 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3 cc cc cc cc e8 7f 9d d3 fe fb 0f 1f 44 00 00 <eb> d7 0f 1f 44 00 00 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3
[117.004879] RSP: 0018:ffffc90000003cf0 EFLAGS: 00000246
[117.004882] RAX: 0000000000000000 RBX: ffff888155e94c40 RCX: 0000000000000000
[117.004884] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[117.004887] RBP: ffffc90000003d00 R08: 0000000000000000 R09: 0000000000000000
[117.004890] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000246
[117.004892] R13: 0000000000000001 R14: 0000000000000246 R15: ffff888155e94c80
[117.004897] dma_fence_signal+0x49/0xb0
[117.004899] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
[117.004902] vgem_fence_timeout+0x12/0x20 [vgem]
[117.004904] call_timer_fn+0xa1/0x2a0
[117.004908] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
[117.004910] __run_timers+0x231/0x310
[117.004913] ? tmigr_handle_remote+0x2ac/0x560
[117.004917] timer_expire_remote+0x46/0x70
[117.004919] tmigr_handle_remote+0x433/0x560
[117.004923] ? __run_timers+0x239/0x310
[117.004925] ? run_timer_softirq+0x21/0xe0
[117.004928] ? lock_release+0xce/0x2a0
[117.004931] run_timer_softirq+0xcf/0xe0
[117.004933] handle_softirqs+0xd4/0x4d0
[117.004936] __irq_exit_rcu+0x13f/0x160
[117.004938] irq_exit_rcu+0xe/0x20
[117.004940] sysvec_apic_timer_interrupt+0xa0/0xc0
[117.004943] </IRQ>
[117.004944] <TASK>
[117.004946] asm_sysvec_apic_timer_interrupt+0x1b/0x20
[117.004949] RIP: 0010:cpuidle_enter_state+0x12b/0x8a0
[117.004953] Code: 48 0f a3 05 97 ce 0e 01 0f 82 2e 03 00 00 31 ff e8 8a 41 bd fe 80 7d d0 00 0f 85 11 03 00 00 e8 8b 06 d5 fe fb 0f 1f 44 00 00 <45> 85 f6 0f 88 67 02 00 00 4d 63 ee 49 83 fd 0a 0f 83 34 06 00 00
[117.004961] RSP: 0018:ffffffff83403d88 EFLAGS: 00000246
[117.004963] RAX: 0000000000000000 RBX: ffff88888f046440 RCX: 0000000000000000
[117.004966] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[117.004968] RBP: ffffffff83403dd8 R08: 0000000000000000 R09: 0000000000000000
[117.004971] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff837cbe80
[117.004974] R13: 0000000000000004 R14: 0000000000000004 R15: 0000001ad1df466b
[117.004978] ? cpuidle_enter_state+0x125/0x8a0
[117.004981] ? sched_clock_noinstr+0x9/0x10
[117.004985] cpuidle_enter+0x2e/0x50
[117.004989] call_cpuidle+0x22/0x60
[117.004991] do_idle+0x1fd/0x260
[117.005001] cpu_startup_entry+0x29/0x30
[117.005004] rest_init+0x104/0x200
[117.005008] start_kernel+0x93d/0xbd0
[117.005011] ? load_ucode_intel_bsp+0x2a/0x90
[117.005014] ? sme_unmap_bootdata+0x14/0x80
[117.005017] x86_64_start_reservations+0x18/0x30
[117.005020] x86_64_start_kernel+0xfd/0x150
[117.005023] ? soft_restart_cpu+0x14/0x14
[117.005026] common_startup_64+0x13e/0x141
[117.005030] </TASK>
[117.005032] irq event stamp: 2282669
[117.005034] hardirqs last enabled at (2282668): [<ffffffff8289db71>] _raw_spin_unlock_irqrestore+0x51/0x80
[117.005038] hardirqs last disabled at (2282669): [<ffffffff82882021>] sysvec_irq_work+0x11/0xc0
[117.005043] softirqs last enabled at (2254702): [<ffffffff8289fd00>] __do_softirq+0x10/0x18
[117.005047] softirqs last disabled at (2254725): [<ffffffff813d4ddf>] __irq_exit_rcu+0x13f/0x160
[117.005051] ---[ end trace 0000000000000000 ]---
Make the timer IRQ safe.
[1] https://patchwork.freedesktop.org/series/154987/#rev2
Fixes: 4077798484459 ("drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)")
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
---
drivers/gpu/drm/vgem/vgem_fence.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
index fd76730fd38c0..07db319c3d7f9 100644
--- a/drivers/gpu/drm/vgem/vgem_fence.c
+++ b/drivers/gpu/drm/vgem/vgem_fence.c
@@ -79,7 +79,7 @@ static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
dma_fence_context_alloc(1), 1);
- timer_setup(&fence->timer, vgem_fence_timeout, 0);
+ timer_setup(&fence->timer, vgem_fence_timeout, TIMER_IRQSAFE);
/* We force the fence to expire within 10s to prevent driver hangs */
mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
--
2.51.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/vgem-fence: Fix potential deadlock on release
2025-09-26 15:26 [PATCH] drm/vgem-fence: Fix potential deadlock on release Janusz Krzysztofik
@ 2025-09-28 14:00 ` Christian König
2025-09-29 12:42 ` Janusz Krzysztofik
0 siblings, 1 reply; 4+ messages in thread
From: Christian König @ 2025-09-28 14:00 UTC (permalink / raw)
To: Janusz Krzysztofik, dri-devel
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, Chris Wilson
On 26.09.25 17:26, Janusz Krzysztofik wrote:
> A timer that expires a vgem fence automatically in 10 seconds is now
> released with timer_delete_sync() from fence->ops.release() called on last
> dma_fence_put(). In some scenarios, it can run in IRQ context, which is
> not safe unless TIMER_IRQSAFE is used. One potentially risky scenario was
> demonstrated in Intel DRM CI trybot, BAT run on machine bat-adlp-6, while
> working on new IGT subtests syncobj_timeline@stress-* as user space
> replacements of some problematic test cases of a dma-fence-chain selftest
> [1].
>
> [117.004338] ================================
> [117.004340] WARNING: inconsistent lock state
> [117.004342] 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 Tainted: G S U
> [117.004346] --------------------------------
> [117.004347] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
> [117.004349] swapper/0/0 [HC1[1]:SC1[1]:HE0:SE0] takes:
> [117.004352] ffff888138f86aa8 ((&fence->timer)){?.-.}-{0:0}, at: __timer_delete_sync+0x4b/0x190
> [117.004361] {HARDIRQ-ON-W} state was registered at:
> [117.004363] lock_acquire+0xc4/0x2e0
> [117.004366] call_timer_fn+0x80/0x2a0
> [117.004368] __run_timers+0x231/0x310
> [117.004370] run_timer_softirq+0x76/0xe0
> [117.004372] handle_softirqs+0xd4/0x4d0
> [117.004375] __irq_exit_rcu+0x13f/0x160
> [117.004377] irq_exit_rcu+0xe/0x20
> [117.004379] sysvec_apic_timer_interrupt+0xa0/0xc0
> [117.004382] asm_sysvec_apic_timer_interrupt+0x1b/0x20
> [117.004385] cpuidle_enter_state+0x12b/0x8a0
> [117.004388] cpuidle_enter+0x2e/0x50
> [117.004393] call_cpuidle+0x22/0x60
> [117.004395] do_idle+0x1fd/0x260
> [117.004398] cpu_startup_entry+0x29/0x30
> [117.004401] start_secondary+0x12d/0x160
> [117.004404] common_startup_64+0x13e/0x141
> [117.004407] irq event stamp: 2282669
> [117.004409] hardirqs last enabled at (2282668): [<ffffffff8289db71>] _raw_spin_unlock_irqrestore+0x51/0x80
> [117.004414] hardirqs last disabled at (2282669): [<ffffffff82882021>] sysvec_irq_work+0x11/0xc0
> [117.004419] softirqs last enabled at (2254702): [<ffffffff8289fd00>] __do_softirq+0x10/0x18
> [117.004423] softirqs last disabled at (2254725): [<ffffffff813d4ddf>] __irq_exit_rcu+0x13f/0x160
> [117.004426]
> other info that might help us debug this:
> [117.004429] Possible unsafe locking scenario:
> [117.004432] CPU0
> [117.004433] ----
> [117.004434] lock((&fence->timer));
> [117.004436] <Interrupt>
> [117.004438] lock((&fence->timer));
> [117.004440]
> *** DEADLOCK ***
> [117.004443] 1 lock held by swapper/0/0:
> [117.004445] #0: ffffc90000003d50 ((&fence->timer)){?.-.}-{0:0}, at: call_timer_fn+0x7a/0x2a0
> [117.004450]
> stack backtrace:
> [117.004453] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G S U 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 PREEMPT(voluntary)
> [117.004455] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
> [117.004455] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
> [117.004456] Call Trace:
> [117.004456] <IRQ>
> [117.004457] dump_stack_lvl+0x91/0xf0
> [117.004460] dump_stack+0x10/0x20
> [117.004461] print_usage_bug.part.0+0x260/0x360
> [117.004463] mark_lock+0x76e/0x9c0
> [117.004465] ? register_lock_class+0x48/0x4a0
> [117.004467] __lock_acquire+0xbc3/0x2860
> [117.004469] lock_acquire+0xc4/0x2e0
> [117.004470] ? __timer_delete_sync+0x4b/0x190
> [117.004472] ? __timer_delete_sync+0x4b/0x190
> [117.004473] __timer_delete_sync+0x68/0x190
> [117.004474] ? __timer_delete_sync+0x4b/0x190
> [117.004475] timer_delete_sync+0x10/0x20
> [117.004476] vgem_fence_release+0x19/0x30 [vgem]
> [117.004478] dma_fence_release+0xc1/0x3b0
> [117.004480] ? dma_fence_release+0xa1/0x3b0
> [117.004481] dma_fence_chain_release+0xe7/0x130
> [117.004483] dma_fence_release+0xc1/0x3b0
> [117.004484] ? _raw_spin_unlock_irqrestore+0x27/0x80
> [117.004485] dma_fence_chain_irq_work+0x59/0x80
> [117.004487] irq_work_single+0x75/0xa0
> [117.004490] irq_work_run_list+0x33/0x60
> [117.004491] irq_work_run+0x18/0x40
> [117.004493] __sysvec_irq_work+0x35/0x170
> [117.004494] sysvec_irq_work+0x47/0xc0
> [117.004496] asm_sysvec_irq_work+0x1b/0x20
> [117.004497] RIP: 0010:_raw_spin_unlock_irqrestore+0x57/0x80
> [117.004499] Code: 00 75 1c 65 ff 0d d9 34 68 01 74 20 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3 cc cc cc cc e8 7f 9d d3 fe fb 0f 1f 44 00 00 <eb> d7 0f 1f 44 00 00 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3
> [117.004499] RSP: 0018:ffffc90000003cf0 EFLAGS: 00000246
> [117.004500] RAX: 0000000000000000 RBX: ffff888155e94c40 RCX: 0000000000000000
> [117.004501] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> [117.004502] RBP: ffffc90000003d00 R08: 0000000000000000 R09: 0000000000000000
> [117.004502] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000246
> [117.004502] R13: 0000000000000001 R14: 0000000000000246 R15: ffff888155e94c80
> [117.004506] dma_fence_signal+0x49/0xb0
> [117.004507] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
> [117.004508] vgem_fence_timeout+0x12/0x20 [vgem]
> [117.004509] call_timer_fn+0xa1/0x2a0
> [117.004512] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
> [117.004513] __run_timers+0x231/0x310
> [117.004514] ? tmigr_handle_remote+0x2ac/0x560
> [117.004517] timer_expire_remote+0x46/0x70
> [117.004518] tmigr_handle_remote+0x433/0x560
> [117.004520] ? __run_timers+0x239/0x310
> [117.004521] ? run_timer_softirq+0x21/0xe0
> [117.004522] ? lock_release+0xce/0x2a0
> [117.004524] run_timer_softirq+0xcf/0xe0
> [117.004525] handle_softirqs+0xd4/0x4d0
> [117.004526] __irq_exit_rcu+0x13f/0x160
> [117.004527] irq_exit_rcu+0xe/0x20
> [117.004528] sysvec_apic_timer_interrupt+0xa0/0xc0
> [117.004529] </IRQ>
> [117.004529] <TASK>
> [117.004529] asm_sysvec_apic_timer_interrupt+0x1b/0x20
> [117.004530] RIP: 0010:cpuidle_enter_state+0x12b/0x8a0
> [117.004532] Code: 48 0f a3 05 97 ce 0e 01 0f 82 2e 03 00 00 31 ff e8 8a 41 bd fe 80 7d d0 00 0f 85 11 03 00 00 e8 8b 06 d5 fe fb 0f 1f 44 00 00 <45> 85 f6 0f 88 67 02 00 00 4d 63 ee 49 83 fd 0a 0f 83 34 06 00 00
> [117.004532] RSP: 0018:ffffffff83403d88 EFLAGS: 00000246
> [117.004533] RAX: 0000000000000000 RBX: ffff88888f046440 RCX: 0000000000000000
> [117.004533] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> [117.004534] RBP: ffffffff83403dd8 R08: 0000000000000000 R09: 0000000000000000
> [117.004534] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff837cbe80
> [117.004534] R13: 0000000000000004 R14: 0000000000000004 R15: 0000001ad1df466b
> [117.004537] ? cpuidle_enter_state+0x125/0x8a0
> [117.004538] ? sched_clock_noinstr+0x9/0x10
> [117.004540] cpuidle_enter+0x2e/0x50
> [117.004542] call_cpuidle+0x22/0x60
> [117.004542] do_idle+0x1fd/0x260
> [117.004544] cpu_startup_entry+0x29/0x30
> [117.004546] rest_init+0x104/0x200
> [117.004548] start_kernel+0x93d/0xbd0
> [117.004550] ? load_ucode_intel_bsp+0x2a/0x90
> [117.004551] ? sme_unmap_bootdata+0x14/0x80
> [117.004554] x86_64_start_reservations+0x18/0x30
> [117.004555] x86_64_start_kernel+0xfd/0x150
> [117.004556] ? soft_restart_cpu+0x14/0x14
> [117.004558] common_startup_64+0x13e/0x141
> [117.004560] </TASK>
> [117.004565] ------------[ cut here ]------------
> [117.004692] WARNING: CPU: 0 PID: 0 at kernel/time/timer.c:1610 __timer_delete_sync+0x126/0x190
> [117.004697] Modules linked in: vgem snd_hda_codec_intelhdmi snd_hda_codec_hdmi i915 prime_numbers ttm drm_buddy drm_display_helper cec rc_core i2c_algo_bit hid_sensor_custom hid_sensor_hub hid_generic intel_ishtp_hid hid intel_uncore_frequency intel_uncore_frequency_common x86_pkg_temp_thermal intel_powerclamp cmdlinepart ee1004 r8153_ecm spi_nor coretemp cdc_ether mei_pxp mei_hdcp usbnet mtd intel_rapl_msr wmi_bmof kvm_intel snd_hda_intel snd_intel_dspcfg processor_thermal_device_pci kvm snd_hda_codec processor_thermal_device irqbypass processor_thermal_wt_hint polyval_clmulni platform_temperature_control snd_hda_core ghash_clmulni_intel processor_thermal_rfim spi_pxa2xx_platform snd_hwdep aesni_intel processor_thermal_rapl dw_dmac snd_pcm dw_dmac_core intel_rapl_common r8152 rapl mii intel_cstate spi_pxa2xx_core i2c_i801 processor_thermal_wt_req snd_timer i2c_mux mei_me intel_ish_ipc processor_thermal_power_floor e1000e snd i2c_smbus spi_intel_pci processor_thermal_mbox mei soundcore intel_ishtp thunderbolt idma64
> [117.004733] spi_intel int340x_thermal_zone igen6_edac binfmt_misc intel_skl_int3472_tps68470 intel_pmc_core tps68470_regulator video clk_tps68470 pmt_telemetry pmt_discovery nls_iso8859_1 pmt_class intel_pmc_ssram_telemetry intel_skl_int3472_discrete int3400_thermal intel_hid intel_skl_int3472_common acpi_thermal_rel intel_vsec wmi pinctrl_tigerlake acpi_tad sparse_keymap acpi_pad dm_multipath msr nvme_fabrics fuse efi_pstore nfnetlink autofs4
> [117.004782] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G S U 6.17.0-rc7-CI_DRM_17270-g7644974e648c+ #1 PREEMPT(voluntary)
> [117.004787] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
> [117.004789] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
> [117.004793] RIP: 0010:__timer_delete_sync+0x126/0x190
> [117.004795] Code: 31 c0 45 31 c9 c3 cc cc cc cc 48 8b 75 d0 45 84 f6 74 63 49 c7 45 18 00 00 00 00 48 89 c7 e8 51 46 39 01 f3 90 e9 66 ff ff ff <0f> 0b e9 5f ff ff ff e8 ee e4 0c 00 49 8d 5d 28 45 31 c9 31 c9 4c
> [117.004801] RSP: 0018:ffffc90000003a40 EFLAGS: 00010046
> [117.004804] RAX: ffffffff815093fb RBX: ffff888138f86aa8 RCX: 0000000000000000
> [117.004807] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> [117.004809] RBP: ffffc90000003a70 R08: 0000000000000000 R09: 0000000000000000
> [117.004812] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff815093fb
> [117.004814] R13: ffff888138f86a80 R14: 0000000000000000 R15: 0000000000000000
> [117.004817] FS: 0000000000000000(0000) GS:ffff88890b0f7000(0000) knlGS:0000000000000000
> [117.004820] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [117.004823] CR2: 00005db8131eb7f0 CR3: 0000000003448000 CR4: 0000000000f52ef0
> [117.004826] PKRU: 55555554
> [117.004827] Call Trace:
> [117.004829] <IRQ>
> [117.004831] timer_delete_sync+0x10/0x20
> [117.004833] vgem_fence_release+0x19/0x30 [vgem]
> [117.004836] dma_fence_release+0xc1/0x3b0
> [117.004838] ? dma_fence_release+0xa1/0x3b0
> [117.004841] dma_fence_chain_release+0xe7/0x130
> [117.004844] dma_fence_release+0xc1/0x3b0
> [117.004847] ? _raw_spin_unlock_irqrestore+0x27/0x80
> [117.004850] dma_fence_chain_irq_work+0x59/0x80
> [117.004853] irq_work_single+0x75/0xa0
> [117.004857] irq_work_run_list+0x33/0x60
> [117.004860] irq_work_run+0x18/0x40
> [117.004863] __sysvec_irq_work+0x35/0x170
> [117.004865] sysvec_irq_work+0x47/0xc0
> [117.004868] asm_sysvec_irq_work+0x1b/0x20
> [117.004871] RIP: 0010:_raw_spin_unlock_irqrestore+0x57/0x80
> [117.004874] Code: 00 75 1c 65 ff 0d d9 34 68 01 74 20 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3 cc cc cc cc e8 7f 9d d3 fe fb 0f 1f 44 00 00 <eb> d7 0f 1f 44 00 00 5b 41 5c 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3
> [117.004879] RSP: 0018:ffffc90000003cf0 EFLAGS: 00000246
> [117.004882] RAX: 0000000000000000 RBX: ffff888155e94c40 RCX: 0000000000000000
> [117.004884] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> [117.004887] RBP: ffffc90000003d00 R08: 0000000000000000 R09: 0000000000000000
> [117.004890] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000246
> [117.004892] R13: 0000000000000001 R14: 0000000000000246 R15: ffff888155e94c80
> [117.004897] dma_fence_signal+0x49/0xb0
> [117.004899] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
> [117.004902] vgem_fence_timeout+0x12/0x20 [vgem]
> [117.004904] call_timer_fn+0xa1/0x2a0
> [117.004908] ? __pfx_vgem_fence_timeout+0x10/0x10 [vgem]
> [117.004910] __run_timers+0x231/0x310
> [117.004913] ? tmigr_handle_remote+0x2ac/0x560
> [117.004917] timer_expire_remote+0x46/0x70
> [117.004919] tmigr_handle_remote+0x433/0x560
> [117.004923] ? __run_timers+0x239/0x310
> [117.004925] ? run_timer_softirq+0x21/0xe0
> [117.004928] ? lock_release+0xce/0x2a0
> [117.004931] run_timer_softirq+0xcf/0xe0
> [117.004933] handle_softirqs+0xd4/0x4d0
> [117.004936] __irq_exit_rcu+0x13f/0x160
> [117.004938] irq_exit_rcu+0xe/0x20
> [117.004940] sysvec_apic_timer_interrupt+0xa0/0xc0
> [117.004943] </IRQ>
> [117.004944] <TASK>
> [117.004946] asm_sysvec_apic_timer_interrupt+0x1b/0x20
> [117.004949] RIP: 0010:cpuidle_enter_state+0x12b/0x8a0
> [117.004953] Code: 48 0f a3 05 97 ce 0e 01 0f 82 2e 03 00 00 31 ff e8 8a 41 bd fe 80 7d d0 00 0f 85 11 03 00 00 e8 8b 06 d5 fe fb 0f 1f 44 00 00 <45> 85 f6 0f 88 67 02 00 00 4d 63 ee 49 83 fd 0a 0f 83 34 06 00 00
> [117.004961] RSP: 0018:ffffffff83403d88 EFLAGS: 00000246
> [117.004963] RAX: 0000000000000000 RBX: ffff88888f046440 RCX: 0000000000000000
> [117.004966] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> [117.004968] RBP: ffffffff83403dd8 R08: 0000000000000000 R09: 0000000000000000
> [117.004971] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff837cbe80
> [117.004974] R13: 0000000000000004 R14: 0000000000000004 R15: 0000001ad1df466b
> [117.004978] ? cpuidle_enter_state+0x125/0x8a0
> [117.004981] ? sched_clock_noinstr+0x9/0x10
> [117.004985] cpuidle_enter+0x2e/0x50
> [117.004989] call_cpuidle+0x22/0x60
> [117.004991] do_idle+0x1fd/0x260
> [117.005001] cpu_startup_entry+0x29/0x30
> [117.005004] rest_init+0x104/0x200
> [117.005008] start_kernel+0x93d/0xbd0
> [117.005011] ? load_ucode_intel_bsp+0x2a/0x90
> [117.005014] ? sme_unmap_bootdata+0x14/0x80
> [117.005017] x86_64_start_reservations+0x18/0x30
> [117.005020] x86_64_start_kernel+0xfd/0x150
> [117.005023] ? soft_restart_cpu+0x14/0x14
> [117.005026] common_startup_64+0x13e/0x141
> [117.005030] </TASK>
> [117.005032] irq event stamp: 2282669
> [117.005034] hardirqs last enabled at (2282668): [<ffffffff8289db71>] _raw_spin_unlock_irqrestore+0x51/0x80
> [117.005038] hardirqs last disabled at (2282669): [<ffffffff82882021>] sysvec_irq_work+0x11/0xc0
> [117.005043] softirqs last enabled at (2254702): [<ffffffff8289fd00>] __do_softirq+0x10/0x18
> [117.005047] softirqs last disabled at (2254725): [<ffffffff813d4ddf>] __irq_exit_rcu+0x13f/0x160
> [117.005051] ---[ end trace 0000000000000000 ]---
>
> Make the timer IRQ safe.
>
> [1] https://patchwork.freedesktop.org/series/154987/#rev2
>
> Fixes: 4077798484459 ("drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)")
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
We should also consider to lower the timeout massively. This needs to be in the range of 100m-1s to not cause the same trouble as the sw_sync framework.
10seconds is just way to long for that.
Regards,
Christian.
> ---
> drivers/gpu/drm/vgem/vgem_fence.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> index fd76730fd38c0..07db319c3d7f9 100644
> --- a/drivers/gpu/drm/vgem/vgem_fence.c
> +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> @@ -79,7 +79,7 @@ static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
> dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
> dma_fence_context_alloc(1), 1);
>
> - timer_setup(&fence->timer, vgem_fence_timeout, 0);
> + timer_setup(&fence->timer, vgem_fence_timeout, TIMER_IRQSAFE);
>
> /* We force the fence to expire within 10s to prevent driver hangs */
> mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/vgem-fence: Fix potential deadlock on release
2025-09-28 14:00 ` Christian König
@ 2025-09-29 12:42 ` Janusz Krzysztofik
2025-10-06 14:21 ` Maarten Lankhorst
0 siblings, 1 reply; 4+ messages in thread
From: Janusz Krzysztofik @ 2025-09-29 12:42 UTC (permalink / raw)
To: dri-devel, Christian König
Cc: Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, Chris Wilson
Hi Christian,
Thank you for looking at it and providing your R-b.
On Sunday, 28 September 2025 16:00:57 CEST Christian König wrote:
> On 26.09.25 17:26, Janusz Krzysztofik wrote:
> > A timer that expires a vgem fence automatically in 10 seconds is now
> > released with timer_delete_sync() from fence->ops.release() called on last
> > dma_fence_put(). In some scenarios, it can run in IRQ context, which is
> > not safe unless TIMER_IRQSAFE is used. One potentially risky scenario was
> > demonstrated in Intel DRM CI trybot, BAT run on machine bat-adlp-6, while
> > working on new IGT subtests syncobj_timeline@stress-* as user space
> > replacements of some problematic test cases of a dma-fence-chain selftest
...
> > Make the timer IRQ safe.
> >
> > [1] https://patchwork.freedesktop.org/series/154987/#rev2
> >
> > Fixes: 4077798484459 ("drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)")
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
>
> Reviewed-by: Christian König <christian.koenig@amd.com>
>
> We should also consider to lower the timeout massively. This needs to be in the range of 100m-1s to not cause the same trouble as the sw_sync framework.
Assuming you are referring to potential hard lockups observed in sw_sync based
version of the exercise, which piece of kernel code you would expect to loop
for too long with interrupts disabled due to the vgem fences auto expiry
timeout of 10s?
>
> 10seconds is just way to long for that.
Do you think DRM objects can't be busy for that long in real life? What about
long running GPU compute tasks?
Thanks,
Janusz
>
> Regards,
> Christian.
>
> > ---
> > drivers/gpu/drm/vgem/vgem_fence.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> > index fd76730fd38c0..07db319c3d7f9 100644
> > --- a/drivers/gpu/drm/vgem/vgem_fence.c
> > +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> > @@ -79,7 +79,7 @@ static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
> > dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
> > dma_fence_context_alloc(1), 1);
> >
> > - timer_setup(&fence->timer, vgem_fence_timeout, 0);
> > + timer_setup(&fence->timer, vgem_fence_timeout, TIMER_IRQSAFE);
> >
> > /* We force the fence to expire within 10s to prevent driver hangs */
> > mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/vgem-fence: Fix potential deadlock on release
2025-09-29 12:42 ` Janusz Krzysztofik
@ 2025-10-06 14:21 ` Maarten Lankhorst
0 siblings, 0 replies; 4+ messages in thread
From: Maarten Lankhorst @ 2025-10-06 14:21 UTC (permalink / raw)
To: Janusz Krzysztofik, dri-devel, Christian König
Cc: Maxime Ripard, Thomas Zimmermann, David Airlie, Simona Vetter,
Chris Wilson
Hey,
Den 2025-09-29 kl. 14:42, skrev Janusz Krzysztofik:
> Hi Christian,
>
> Thank you for looking at it and providing your R-b.
>
> On Sunday, 28 September 2025 16:00:57 CEST Christian König wrote:
>> On 26.09.25 17:26, Janusz Krzysztofik wrote:
>>> A timer that expires a vgem fence automatically in 10 seconds is now
>>> released with timer_delete_sync() from fence->ops.release() called on last
>>> dma_fence_put(). In some scenarios, it can run in IRQ context, which is
>>> not safe unless TIMER_IRQSAFE is used. One potentially risky scenario was
>>> demonstrated in Intel DRM CI trybot, BAT run on machine bat-adlp-6, while
>>> working on new IGT subtests syncobj_timeline@stress-* as user space
>>> replacements of some problematic test cases of a dma-fence-chain selftest
> ...
>>> Make the timer IRQ safe.
>>>
>>> [1] https://patchwork.freedesktop.org/series/154987/#rev2
>>>
>>> Fixes: 4077798484459 ("drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)")
>>> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
>>
>> Reviewed-by: Christian König <christian.koenig@amd.com>
>>
>> We should also consider to lower the timeout massively. This needs to be in the range of 100m-1s to not cause the same trouble as the sw_sync framework.
>
> Assuming you are referring to potential hard lockups observed in sw_sync based
> version of the exercise, which piece of kernel code you would expect to loop
> for too long with interrupts disabled due to the vgem fences auto expiry
> timeout of 10s?
>
>>
>> 10seconds is just way to long for that.
>
> Do you think DRM objects can't be busy for that long in real life? What about
> long running GPU compute tasks?
>
> Thanks,
> Janusz
>
>
>>
>> Regards,
>> Christian.
>>
>>> ---
>>> drivers/gpu/drm/vgem/vgem_fence.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
>>> index fd76730fd38c0..07db319c3d7f9 100644
>>> --- a/drivers/gpu/drm/vgem/vgem_fence.c
>>> +++ b/drivers/gpu/drm/vgem/vgem_fence.c
>>> @@ -79,7 +79,7 @@ static struct dma_fence *vgem_fence_create(struct vgem_file *vfile,
>>> dma_fence_init(&fence->base, &vgem_fence_ops, &fence->lock,
>>> dma_fence_context_alloc(1), 1);
>>>
>>> - timer_setup(&fence->timer, vgem_fence_timeout, 0);
>>> + timer_setup(&fence->timer, vgem_fence_timeout, TIMER_IRQSAFE);
>>>
>>> /* We force the fence to expire within 10s to prevent driver hangs */
>>> mod_timer(&fence->timer, jiffies + VGEM_FENCE_TIMEOUT);
>>
>>
>
>
>
>
Pushed the ptach, thanks.
I'm imagining it's mostly because of potential chaining of multiple fences, which can worsen the worst-case timeout easily.
Kind regards,
~Maarten
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-10-06 14:21 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2025-09-26 15:26 [PATCH] drm/vgem-fence: Fix potential deadlock on release Janusz Krzysztofik
2025-09-28 14:00 ` Christian König
2025-09-29 12:42 ` Janusz Krzysztofik
2025-10-06 14:21 ` Maarten Lankhorst
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