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Date: Thu, 19 Nov 2020 14:02:44 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Heiner Kallweit <hkallweit1@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: Deadlock cpuctx_mutex / pmus_lock / &mm->mmap_lock#2
Chris, I suspect this is due to i915 calling stop machine with all sorts
of locks held. Is there anything to be done about this? stop_machine()
is really nasty to begin with.
What problem is it typing to solve?
On Thu, Nov 19, 2020 at 12:04:56AM +0100, Heiner Kallweit wrote:
> Just got the following when running perf.
>
> [ 648.247718] ======================================================
> [ 648.247725] WARNING: possible circular locking dependency detected
> [ 648.247734] 5.10.0-rc4-next-20201118+ #1 Not tainted
> [ 648.247740] ------------------------------------------------------
> [ 648.247748] perf/19761 is trying to acquire lock:
> [ 648.247755] ffffa00200abad18 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0x2f/0x80
> [ 648.247777]
> but task is already holding lock:
> [ 648.247785] ffffa0027bc2edb0 (&cpuctx_mutex){+.+.}-{3:3}, at: perf_event_ctx_lock_nested+0xd8/0x1f0
> [ 648.247801]
> which lock already depends on the new lock.
>
> [ 648.247810]
> the existing dependency chain (in reverse order) is:
> [ 648.247818]
> -> #5 (&cpuctx_mutex){+.+.}-{3:3}:
> [ 648.247834] __mutex_lock+0x88/0x900
> [ 648.247840] mutex_lock_nested+0x16/0x20
> [ 648.247848] perf_event_init_cpu+0x89/0x140
> [ 648.247857] perf_event_init+0x172/0x1a0
> [ 648.247864] start_kernel+0x655/0x7de
> [ 648.247871] x86_64_start_reservations+0x24/0x26
> [ 648.247878] x86_64_start_kernel+0x70/0x74
> [ 648.247887] secondary_startup_64_no_verify+0xb0/0xbb
> [ 648.247894]
> -> #4 (pmus_lock){+.+.}-{3:3}:
> [ 648.247907] __mutex_lock+0x88/0x900
> [ 648.247914] mutex_lock_nested+0x16/0x20
> [ 648.247921] perf_event_init_cpu+0x52/0x140
> [ 648.247929] cpuhp_invoke_callback+0xa4/0x810
> [ 648.247937] _cpu_up+0xaa/0x150
> [ 648.247943] cpu_up+0x79/0x90
> [ 648.247949] bringup_nonboot_cpus+0x4d/0x60
> [ 648.247958] smp_init+0x25/0x65
> [ 648.247964] kernel_init_freeable+0x144/0x267
> [ 648.247972] kernel_init+0x9/0xf8
> [ 648.247978] ret_from_fork+0x22/0x30
> [ 648.247984]
> -> #3 (cpu_hotplug_lock){++++}-{0:0}:
> [ 648.247998] cpus_read_lock+0x38/0xb0
> [ 648.248006] stop_machine+0x18/0x40
> [ 648.248075] bxt_vtd_ggtt_insert_entries__BKL+0x37/0x50 [i915]
> [ 648.248129] ggtt_bind_vma+0x43/0x60 [i915]
> [ 648.248192] __vma_bind+0x38/0x40 [i915]
> [ 648.248242] fence_work+0x21/0xac [i915]
> [ 648.248292] fence_notify+0x95/0x134 [i915]
> [ 648.248342] __i915_sw_fence_complete+0x3b/0x1d0 [i915]
> [ 648.248394] i915_sw_fence_commit+0x12/0x20 [i915]
> [ 648.248458] i915_vma_pin_ww+0x25c/0x8c0 [i915]
> [ 648.248520] i915_ggtt_pin+0x52/0xf0 [i915]
> [ 648.248576] intel_ring_pin+0x5b/0x110 [i915]
> [ 648.248628] __intel_context_do_pin_ww+0xd3/0x510 [i915]
> [ 648.248681] __intel_context_do_pin+0x55/0x90 [i915]
> [ 648.248734] intel_engines_init+0x43d/0x570 [i915]
> [ 648.248787] intel_gt_init+0x119/0x2d0 [i915]
> [ 648.248848] i915_gem_init+0x133/0x1c0 [i915]
> [ 648.248895] i915_driver_probe+0x68d/0xc90 [i915]
> [ 648.248943] i915_pci_probe+0x45/0x120 [i915]
> [ 648.248952] pci_device_probe+0xd8/0x150
> [ 648.248960] really_probe+0x259/0x460
> [ 648.248967] driver_probe_device+0x50/0xb0
> [ 648.248973] device_driver_attach+0xad/0xc0
> [ 648.248980] __driver_attach+0x75/0x110
> [ 648.248988] bus_for_each_dev+0x7c/0xc0
> [ 648.248995] driver_attach+0x19/0x20
> [ 648.249001] bus_add_driver+0x117/0x1c0
> [ 648.249008] driver_register+0x8c/0xe0
> [ 648.249015] __pci_register_driver+0x6e/0x80
> [ 648.249022] 0xffffffffc0a5c061
> [ 648.249028] do_one_initcall+0x5a/0x2c0
> [ 648.249036] do_init_module+0x5d/0x240
> [ 648.249043] load_module+0x2367/0x2710
> [ 648.249049] __do_sys_finit_module+0xb6/0xf0
> [ 648.249056] __x64_sys_finit_module+0x15/0x20
> [ 648.249064] do_syscall_64+0x38/0x50
> [ 648.249071] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 648.249078]
> -> #2 (reservation_ww_class_mutex){+.+.}-{3:3}:
> [ 648.249093] __ww_mutex_lock.constprop.0+0xac/0x1090
> [ 648.249100] ww_mutex_lock+0x3d/0xa0
> [ 648.249108] dma_resv_lockdep+0x141/0x281
> [ 648.249114] do_one_initcall+0x5a/0x2c0
> [ 648.249121] kernel_init_freeable+0x220/0x267
> [ 648.249129] kernel_init+0x9/0xf8
> [ 648.249135] ret_from_fork+0x22/0x30
> [ 648.249140]
> -> #1 (reservation_ww_class_acquire){+.+.}-{0:0}:
> [ 648.249155] dma_resv_lockdep+0x115/0x281
> [ 648.249162] do_one_initcall+0x5a/0x2c0
> [ 648.249168] kernel_init_freeable+0x220/0x267
> [ 648.249176] kernel_init+0x9/0xf8
> [ 648.249182] ret_from_fork+0x22/0x30
> [ 648.249188]
> -> #0 (&mm->mmap_lock#2){++++}-{3:3}:
> [ 648.249203] __lock_acquire+0x125d/0x2160
> [ 648.249210] lock_acquire+0x137/0x3e0
> [ 648.249217] __might_fault+0x59/0x80
> [ 648.249223] perf_copy_attr+0x35/0x340
> [ 648.249230] _perf_ioctl+0x3e1/0xd40
> [ 648.249237] perf_ioctl+0x34/0x60
> [ 648.249245] __x64_sys_ioctl+0x8c/0xb0
> [ 648.249252] do_syscall_64+0x38/0x50
> [ 648.249259] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 648.249265]
> other info that might help us debug this:
>
> [ 648.249277] Chain exists of:
> &mm->mmap_lock#2 --> pmus_lock --> &cpuctx_mutex
>
> [ 648.249295] Possible unsafe locking scenario:
>
> [ 648.249302] CPU0 CPU1
> [ 648.249308] ---- ----
> [ 648.249314] lock(&cpuctx_mutex);
> [ 648.249321] lock(pmus_lock);
> [ 648.249330] lock(&cpuctx_mutex);
> [ 648.249339] lock(&mm->mmap_lock#2);
> [ 648.249347]
> *** DEADLOCK ***
>
> [ 648.249355] 1 lock held by perf/19761:
> [ 648.249360] #0: ffffa0027bc2edb0 (&cpuctx_mutex){+.+.}-{3:3}, at: perf_event_ctx_lock_nested+0xd8/0x1f0
> [ 648.249377]
> stack backtrace:
> [ 648.249386] CPU: 0 PID: 19761 Comm: perf Not tainted 5.10.0-rc4-next-20201118+ #1
> [ 648.249395] Hardware name: NA ZBOX-CI327NANO-GS-01/ZBOX-CI327NANO-GS-01, BIOS 5.12 04/28/2020
> [ 648.249405] Call Trace:
> [ 648.249413] dump_stack+0x7d/0x9f
> [ 648.249420] print_circular_bug.cold+0x13c/0x141
> [ 648.249428] check_noncircular+0xf1/0x110
> [ 648.249435] __lock_acquire+0x125d/0x2160
> [ 648.249442] lock_acquire+0x137/0x3e0
> [ 648.249449] ? __might_fault+0x2f/0x80
> [ 648.249456] __might_fault+0x59/0x80
> [ 648.249463] ? __might_fault+0x2f/0x80
> [ 648.249469] perf_copy_attr+0x35/0x340
> [ 648.249476] _perf_ioctl+0x3e1/0xd40
> [ 648.249482] ? __mutex_lock+0x88/0x900
> [ 648.249489] ? perf_event_ctx_lock_nested+0xd8/0x1f0
> [ 648.249497] ? perf_event_ctx_lock_nested+0x1a/0x1f0
> [ 648.249504] ? mutex_lock_nested+0x16/0x20
> [ 648.249511] perf_ioctl+0x34/0x60
> [ 648.249518] __x64_sys_ioctl+0x8c/0xb0
> [ 648.249524] do_syscall_64+0x38/0x50
> [ 648.249531] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 648.249539] RIP: 0033:0x7f68dd378f6b
> [ 648.249548] Code: 89 d8 49 8d 3c 1c 48 f7 d8 49 39 c4 72 b5 e8 1c ff ff ff 85 c0 78 ba 4c 89 e0 5b 5d 41 5c c3 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d d5 ae 0c 00 f7 d8 64 89 01 48
> [ 648.249566] RSP: 002b:00007ffd6c018c58 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
> [ 648.249577] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f68dd378f6b
> [ 648.249586] RDX: 00007ffd6c018c90 RSI: 000000004008240b RDI: 0000000000000003
> [ 648.249594] RBP: 00007ffd6c018d40 R08: 0000000000000008 R09: 0000003000000018
> [ 648.249602] R10: fffffffffffff8f8 R11: 0000000000000202 R12: 0000000000000003
> [ 648.249611] R13: 00007ffd6c018c90 R14: 0000007800000005 R15: 000080056c01a5a0
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