Re: [perf] vsyscall, possible circular locking dependency detected
From: Vince Weaver
Date: Wed Jan 03 2024 - 14:13:32 EST
On Wed, 3 Jan 2024, Ian Rogers wrote:
> On Wed, Jan 3, 2024 at 10:08 AM Ian Rogers <irogers@xxxxxxxxxx> wrote:
> >
> > On Wed, Dec 13, 2023 at 7:08 AM Vince Weaver <vincent.weaver@xxxxxxxxx> wrote:
> > >
> > > Hello
> > >
> > > I recently added vsyscall fuzzing support to the perf_fuzzer and it gave
> > > me this dump when fuzzing on a haswell machine running current git
> > > (6.7.0-rc5+)
> > >
> > > [12559.226693] ======================================================
> > > [12559.232906] WARNING: possible circular locking dependency detected
> > > [12559.239116] 6.7.0-rc5+ #1 Tainted: G W
> > > [12559.244286] ------------------------------------------------------
> > > [12559.250493] perf_fuzzer/284551 is trying to acquire lock:
> > > [12559.255923] ffff88800aff65d8 (&sighand->siglock){-.-.}-{2:2}, at: force_sig_info_to_task+0x41/0x260
> > > [12559.265034]
> > > but task is already holding lock:
> > > [12559.270891] ffff8880d08bd4d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0xb0
> > > [12559.279463]
> > > which lock already depends on the new lock.
> > >
> > > [12559.287670]
> > > the existing dependency chain (in reverse order) is:
> > > [12559.295182]
> > > -> #1 (&rq->__lock){-.-.}-{2:2}:
> > > [12559.300966] _raw_spin_lock_nested+0x32/0x40
> > > [12559.305789] raw_spin_rq_lock_nested+0x26/0xb0
> > > [12559.310783] _raw_spin_rq_lock_irqsave+0x23/0x60
> > > [12559.315959] sched_mm_cid_before_execve+0xcd/0x3d0
> > > [12559.321306] exit_signals+0x1a3/0x450
> > > [12559.325521] do_exit+0x24b/0x1100
> > > [12559.329389] __x64_sys_exit+0x2c/0x30
> > > [12559.333600] do_syscall_64+0x41/0x120
> > > [12559.337814] entry_SYSCALL_64_after_hwframe+0x6e/0x76
> > > [12559.343423]
> > > -> #0 (&sighand->siglock){-.-.}-{2:2}:
> > > [12559.349732] __lock_acquire+0x1d8d/0x31f0
> > > [12559.354296] lock_acquire+0x16c/0x3e0
> > > [12559.358506] _raw_spin_lock_irqsave+0x47/0x70
> > > [12559.363416] force_sig_info_to_task+0x41/0x260
> > > [12559.368418] force_sig_fault+0xaa/0xf0
> > > [12559.372722] exc_page_fault+0x61/0xf0
> > > [12559.376932] asm_exc_page_fault+0x22/0x30
> > > [12559.381494] __get_user_handle_exception+0x0/0x20
> > > [12559.386755] perf_callchain_user+0x2d3/0x390
> > > [12559.391581] get_perf_callchain+0x21a/0x2d0
> > > [12559.396312] perf_callchain+0xc3/0xe0
> > > [12559.400526] perf_prepare_sample+0x4f1/0xc70
> > > [12559.405346] perf_event_output_forward+0xbf/0x270
> > > [12559.410599] __perf_event_overflow+0x1ad/0x3c0
> > > [12559.415597] ___perf_sw_event+0x1f7/0x390
> > > [12559.420154] __schedule+0x12d3/0x2560
> > > [12559.424367] preempt_schedule_irq+0x47/0x90
> > > [12559.429098] irqentry_exit+0x31/0x80
> > > [12559.433223] asm_sysvec_apic_timer_interrupt+0x16/0x20
> > > [12559.438912] seqcount_lockdep_reader_access.constprop.0+0x88/0x90
> > > [12559.445562] ktime_get_real_ts64+0x28/0x120
> > > [12559.450297] __x64_sys_gettimeofday+0x86/0x150
> > > [12559.455292] emulate_vsyscall+0x258/0x590
> > > [12559.459858] do_user_addr_fault+0x346/0x8c0
> > > [12559.464588] exc_page_fault+0x61/0xf0
> > > [12559.468798] asm_exc_page_fault+0x22/0x30
> > > [12559.473360] _end+0x7a5da000/0x0
> > > [12559.477135]
> > > other info that might help us debug this:
> > >
> > > [12559.485163] Possible unsafe locking scenario:
> > >
> > > [12559.491115] CPU0 CPU1
> > > [12559.495670] ---- ----
> > > [12559.500228] lock(&rq->__lock);
> > > [12559.503492] lock(&sighand->siglock);
> > > [12559.509791] lock(&rq->__lock);
> > > [12559.515569] lock(&sighand->siglock);
> > > [12559.519352]
> > > *** DEADLOCK ***
> > >
> > > [12559.525303] 3 locks held by perf_fuzzer/284551:
> > > [12559.529867] #0: ffff8880d08bd4d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0xb0
> > > [12559.538873] #1: ffffffff831a3ec0 (rcu_read_lock){....}-{1:2}, at: ___perf_sw_event+0x10f/0x390
> > > [12559.547618] #2: ffffffff831a3ec0 (rcu_read_lock){....}-{1:2}, at: perf_event_output_forward+0x8f/0x270
> > > [12559.557058]
> > > stack backtrace:
> > > [12559.561439] CPU: 5 PID: 284551 Comm: perf_fuzzer Tainted: G W 6.7.0-rc5+ #1
> > > [12559.569823] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
> > > [12559.577248] Call Trace:
> > > [12559.579720] <TASK>
> > > [12559.581846] dump_stack_lvl+0x57/0x90
> > > [12559.585539] check_noncircular+0x24f/0x290
> > > [12559.589668] ? __pfx_check_noncircular+0x10/0x10
> > > [12559.594327] ? lockdep_lock+0xb3/0x170
> > > [12559.598106] ? __pfx_lockdep_lock+0x10/0x10
> > > [12559.602323] ? add_chain_block+0x2dc/0x300
> > > [12559.606456] __lock_acquire+0x1d8d/0x31f0
> > > [12559.610508] ? __pfx___lock_acquire+0x10/0x10
> > > [12559.614896] ? __pfx_mark_lock+0x10/0x10
> > > [12559.618849] lock_acquire+0x16c/0x3e0
> > > [12559.622548] ? force_sig_info_to_task+0x41/0x260
> > > [12559.627197] ? __pfx_lock_acquire+0x10/0x10
> > > [12559.631414] ? __pfx_mark_lock+0x10/0x10
> > > [12559.635370] ? mark_lock+0x10b/0xd40
> > > [12559.638981] ? mark_lock+0x10b/0xd40
> > > [12559.642586] _raw_spin_lock_irqsave+0x47/0x70
> > > [12559.646971] ? force_sig_info_to_task+0x41/0x260
> > > [12559.651618] force_sig_info_to_task+0x41/0x260
> > > [12559.656101] force_sig_fault+0xaa/0xf0
> > > [12559.659882] ? __pfx_force_sig_fault+0x10/0x10
> > > [12559.664360] ? kernelmode_fixup_or_oops+0x10a/0x150
> > > [12559.669272] exc_page_fault+0x61/0xf0
> > > [12559.672964] asm_exc_page_fault+0x22/0x30
> > > [12559.677007] RIP: 0010:__get_user_handle_exception+0x0/0x20
> > > [12559.682524] Code: 90 90 90 90 90 90 90 90 90 90 0f 1f 00 0f ae e8 48 8b 10 31 c0 0f 1f 00 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 <0f> 1f 00 31 d2 48 c7 c0 f2 ff ff ff c3 cc cc cc cc cc cc cc cc cc
> > > [12559.701336] RSP: 0000:ffffc90021bef5d0 EFLAGS: 00010006
> > > [12559.706592] RAX: 0000000000000005 RBX: ffffc90021bef680 RCX: ffffffff8100a5a3
> > > [12559.713764] RDX: 0000000000000011 RSI: ffffffff8100a55d RDI: ffff8880138d8090
> > > [12559.720931] RBP: 0000000000000005 R08: 0000000000000000 R09: fffffbfff0799b5c
> > > [12559.728098] R10: ffffffff83ccdae1 R11: 0000000000000000 R12: ffffc90021bef68c
> > > [12559.735266] R13: ffffc90021bef688 R14: 0000000000000005 R15: ffff8880138d8000
> > > [12559.742436] ? perf_callchain_user+0x353/0x390
> > > [12559.746914] ? perf_callchain_user+0x30d/0x390
> > > [12559.751391] perf_callchain_user+0x2d3/0x390
> > > [12559.755699] get_perf_callchain+0x21a/0x2d0
> > > [12559.759917] ? __pfx_get_perf_callchain+0x10/0x10
> > > [12559.764662] ? lock_is_held_type+0xe3/0x140
> > > [12559.768882] ? preempt_schedule_irq+0x47/0x90
> > > [12559.773269] perf_callchain+0xc3/0xe0
> > > [12559.776961] perf_prepare_sample+0x4f1/0xc70
> > > [12559.781263] ? __pfx_perf_prepare_sample+0x10/0x10
> > > [12559.786084] ? __pfx___lock_acquire+0x10/0x10
> > > [12559.790478] perf_event_output_forward+0xbf/0x270
> > > [12559.795214] ? __pfx_perf_event_output_forward+0x10/0x10
> > > [12559.800554] ? lock_acquire+0x16c/0x3e0
> > > [12559.804420] ? lock_acquire+0x17c/0x3e0
> > > [12559.808295] ? __pfx_lock_acquire+0x10/0x10
> > > [12559.812511] ? ___perf_sw_event+0x22f/0x390
> > > [12559.816727] ? __pfx_lock_release+0x10/0x10
> > > [12559.820951] __perf_event_overflow+0x1ad/0x3c0
> > > [12559.825428] ___perf_sw_event+0x1f7/0x390
> > > [12559.829467] ? __pfx____perf_sw_event+0x10/0x10
> > > [12559.834037] ? preempt_schedule_irq+0x47/0x90
> > > [12559.838426] ? __update_load_avg_se+0x86/0x5c0
> > > [12559.842900] ? __update_load_avg_cfs_rq+0x70/0x570
> > > [12559.847726] ? lock_acquire+0x16c/0x3e0
> > > [12559.851590] ? __update_load_avg_se+0x15f/0x5c0
> > > [12559.856154] ? lock_is_held_type+0xe3/0x140
> > > [12559.860372] ? update_load_avg+0x154/0xdc0
> > > [12559.864499] ? lock_is_held_type+0xe3/0x140
> > > [12559.868721] ? set_next_entity+0xec/0x1e0
> > > [12559.872764] ? preempt_schedule_irq+0x47/0x90
> > > [12559.877149] ? __schedule+0x12d3/0x2560
> > > [12559.881012] __schedule+0x12d3/0x2560
> > > [12559.884717] ? __pfx___schedule+0x10/0x10
> > > [12559.888754] ? __pfx___lock_acquire+0x10/0x10
> > > [12559.893139] ? lock_is_held_type+0xe3/0x140
> > > [12559.897353] ? mark_held_locks+0x24/0x90
> > > [12559.901316] preempt_schedule_irq+0x47/0x90
> > > [12559.905531] irqentry_exit+0x31/0x80
> > > [12559.909136] asm_sysvec_apic_timer_interrupt+0x16/0x20
> > > [12559.914305] RIP: 0010:seqcount_lockdep_reader_access.constprop.0+0x88/0x90
> > > [12559.921217] Code: 31 f6 48 c7 c7 48 7c 1c 83 e8 84 25 f8 ff 48 8b 74 24 08 48 c7 c7 48 7c 1c 83 e8 93 1c f8 ff e8 6e d2 0c 00 fb 0f 1f 44 00 00 <5a> c3 cc cc cc cc 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
> > > [12559.940025] RSP: 0000:ffffc90021befdb8 EFLAGS: 00000202
> > > [12559.945281] RAX: 000000000182a8d9 RBX: ffffc90021befe18 RCX: dffffc0000000000
> > > [12559.952453] RDX: 0000000000000000 RSI: ffffffff826804e0 RDI: ffffffff828c8620
> > > [12559.959619] RBP: 00007ffcf0f36fd0 R08: 0000000000000001 R09: 0000000000000001
> > > [12559.966786] R10: ffffffff8371fd27 R11: 0000000000000000 R12: 0000000000000000
> > > [12559.973953] R13: 0000000000000000 R14: ffff88800aa55340 R15: ffffc90021befff0
> > > [12559.981129] ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90
> > > [12559.987426] ? ktime_get_real_ts64+0x28/0x120
> > > [12559.991820] ktime_get_real_ts64+0x28/0x120
> > > [12559.996032] __x64_sys_gettimeofday+0x86/0x150
> > > [12560.000512] ? __pfx___x64_sys_gettimeofday+0x10/0x10
> > > [12560.005602] ? do_user_addr_fault+0x3c5/0x8c0
> > > [12560.009994] emulate_vsyscall+0x258/0x590
> > > [12560.014034] ? 0xffffffffff600000
> > > [12560.017376] do_user_addr_fault+0x346/0x8c0
> > > [12560.021587] ? rcu_is_watching+0x34/0x60
> > > [12560.025541] ? 0xffffffffff600000
> > > [12560.028882] exc_page_fault+0x61/0xf0
> > > [12560.032578] asm_exc_page_fault+0x22/0x30
> > > [12560.036616] RIP: 0033:_end+0x7a5da000/0x0
> > > [12560.040653] Code: Unable to access opcode bytes at 0xffffffffff5fffd6.
> > > [12560.047210] RSP: 002b:00007ffcf0f36fb8 EFLAGS: 00010246
> > > [12560.052470] RAX: ffffffffffffffda RBX: 000000000000000d RCX: 000000000000000a
> > > [12560.059632] RDX: 0000000000000010 RSI: 0000000000000000 RDI: 00007ffcf0f36fd0
> > > [12560.066799] RBP: 00007ffcf0f36fc0 R08: 00007f482684b274 R09: 00007f482684b280
> > > [12560.073966] R10: 00007f4826675a10 R11: 0000000000000246 R12: 0000000000000000
> > > [12560.081132] R13: 00007ffcf0f39448 R14: 000055f2641d2dd8 R15: 00007f48268a3000
> > > [12560.088304] </TASK>
> >
> > Thanks Vince, the potential deadlock is bad. I notice you updated your tests at:
> > https://github.com/deater/perf_event_tests
> > is there a simple reproduction for this failure? Has there been any
> > other progress on this issue?
>
> Apologies, I just saw the syzkaller reproduction and your comments:
>
>https://lore.kernel.org/lkml/CABOYnLxoG=YsE1XyOjfF0O+2UrdTyK1JMir3xPapGsRzh -XFAA@xxxxxxxxxxxxxx/
I think that is a separate bug.
The warning from the link you provide is
WARNING: CPU: 1 PID: 8266 at kernel/events/core.c:1950 __do_sys_perf_event_open0
and the perf_fuzzer can trigger this within seconds (and apparently
trinity and syzkaller all triggered it as well).
The deadlock mentioned in the e-mail you are replying to here is different
and took many hours before triggering, and I think is vsyscall related.
I only recently added vsyscall support to the fuzzer.
I don't necessarily have a reproducer for it. I can try to trigger it
again and get one together. There was a power outage so my fuzzing
machines are all down and I need to get them running again.
Vince