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bpf: avoid hashtab deadlock with try_lock
The commit 20b6cc3 ("bpf: Avoid hashtab deadlock with map_locked"), try to fix deadlock, but in some case, the deadlock occurs: * CPUn in task context with K1, and taking lock. * CPUn interrupted by NMI context, with K2. * They are using the same bucket, but different map_locked. | Task | +---v----+ | CPUn | +---^----+ | | NMI Anyway, the lockdep still warn: [ 36.092222] ================================ [ 36.092230] WARNING: inconsistent lock state [ 36.092234] 6.1.0-rc5+ torvalds#81 Tainted: G E [ 36.092236] -------------------------------- [ 36.092237] inconsistent {INITIAL USE} -> {IN-NMI} usage. [ 36.092238] perf/1515 [HC1[1]:SC0[0]:HE0:SE1] takes: [ 36.092242] ffff888341acd1a0 (&htab->lockdep_key){....}-{2:2}, at: htab_lock_bucket+0x4d/0x58 [ 36.092253] {INITIAL USE} state was registered at: [ 36.092255] mark_usage+0x1d/0x11d [ 36.092262] __lock_acquire+0x3c9/0x6ed [ 36.092266] lock_acquire+0x23d/0x29a [ 36.092270] _raw_spin_lock_irqsave+0x43/0x7f [ 36.092274] htab_lock_bucket+0x4d/0x58 [ 36.092276] htab_map_delete_elem+0x82/0xfb [ 36.092278] map_delete_elem+0x156/0x1ac [ 36.092282] __sys_bpf+0x138/0xb71 [ 36.092285] __do_sys_bpf+0xd/0x15 [ 36.092288] do_syscall_64+0x6d/0x84 [ 36.092291] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 36.092295] irq event stamp: 120346 [ 36.092296] hardirqs last enabled at (120345): [<ffffffff8180b97f>] _raw_spin_unlock_irq+0x24/0x39 [ 36.092299] hardirqs last disabled at (120346): [<ffffffff81169e85>] generic_exec_single+0x40/0xb9 [ 36.092303] softirqs last enabled at (120268): [<ffffffff81c00347>] __do_softirq+0x347/0x387 [ 36.092307] softirqs last disabled at (120133): [<ffffffff810ba4f0>] __irq_exit_rcu+0x67/0xc6 [ 36.092311] [ 36.092311] other info that might help us debug this: [ 36.092312] Possible unsafe locking scenario: [ 36.092312] [ 36.092313] CPU0 [ 36.092313] ---- [ 36.092314] lock(&htab->lockdep_key); [ 36.092315] <Interrupt> [ 36.092316] lock(&htab->lockdep_key); [ 36.092318] [ 36.092318] *** DEADLOCK *** [ 36.092318] [ 36.092318] 3 locks held by perf/1515: [ 36.092320] #0: ffff8881b9805cc0 (&cpuctx_mutex){+.+.}-{4:4}, at: perf_event_ctx_lock_nested+0x8e/0xba [ 36.092327] #1: ffff8881075ecc20 (&event->child_mutex){+.+.}-{4:4}, at: perf_event_for_each_child+0x35/0x76 [ 36.092332] #2: ffff8881b9805c20 (&cpuctx_lock){-.-.}-{2:2}, at: perf_ctx_lock+0x12/0x27 [ 36.092339] [ 36.092339] stack backtrace: [ 36.092341] CPU: 0 PID: 1515 Comm: perf Tainted: G E 6.1.0-rc5+ torvalds#81 [ 36.092344] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 [ 36.092349] Call Trace: [ 36.092351] <NMI> [ 36.092354] dump_stack_lvl+0x57/0x81 [ 36.092359] lock_acquire+0x1f4/0x29a [ 36.092363] ? handle_pmi_common+0x13f/0x1f0 [ 36.092366] ? htab_lock_bucket+0x4d/0x58 [ 36.092371] _raw_spin_lock_irqsave+0x43/0x7f [ 36.092374] ? htab_lock_bucket+0x4d/0x58 [ 36.092377] htab_lock_bucket+0x4d/0x58 [ 36.092379] htab_map_update_elem+0x11e/0x220 [ 36.092386] bpf_prog_f3a535ca81a8128a_bpf_prog2+0x3e/0x42 [ 36.092392] trace_call_bpf+0x177/0x215 [ 36.092398] perf_trace_run_bpf_submit+0x52/0xaa [ 36.092403] ? x86_pmu_stop+0x97/0x97 [ 36.092407] perf_trace_nmi_handler+0xb7/0xe0 [ 36.092415] nmi_handle+0x116/0x254 [ 36.092418] ? x86_pmu_stop+0x97/0x97 [ 36.092423] default_do_nmi+0x3d/0xf6 [ 36.092428] exc_nmi+0xa1/0x109 [ 36.092432] end_repeat_nmi+0x16/0x67 [ 36.092436] RIP: 0010:wrmsrl+0xd/0x1b [ 36.092441] Code: 04 01 00 00 c6 84 07 48 01 00 00 01 5b e9 46 15 80 00 5b c3 cc cc cc cc c3 cc cc cc cc 48 89 f2 89 f9 89 f0 48 c1 ea 20 0f 30 <66> 90 c3 cc cc cc cc 31 d2 e9 2f 04 49 00 0f 1f 44 00 00 40 0f6 [ 36.092443] RSP: 0018:ffffc900043dfc48 EFLAGS: 00000002 [ 36.092445] RAX: 000000000000000f RBX: ffff8881b96153e0 RCX: 000000000000038f [ 36.092447] RDX: 0000000000000007 RSI: 000000070000000f RDI: 000000000000038f [ 36.092449] RBP: 000000070000000f R08: ffffffffffffffff R09: ffff8881053bdaa8 [ 36.092451] R10: ffff8881b9805d40 R11: 0000000000000005 R12: ffff8881b9805c00 [ 36.092452] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8881075ec970 [ 36.092460] ? wrmsrl+0xd/0x1b [ 36.092465] ? wrmsrl+0xd/0x1b [ 36.092469] </NMI> [ 36.092469] <TASK> [ 36.092470] __intel_pmu_enable_all.constprop.0+0x7c/0xaf [ 36.092475] event_function+0xb6/0xd3 [ 36.092478] ? cpu_to_node+0x1a/0x1a [ 36.092482] ? cpu_to_node+0x1a/0x1a [ 36.092485] remote_function+0x1e/0x4c [ 36.092489] generic_exec_single+0x48/0xb9 [ 36.092492] ? __lock_acquire+0x666/0x6ed [ 36.092497] smp_call_function_single+0xbf/0x106 [ 36.092499] ? cpu_to_node+0x1a/0x1a [ 36.092504] ? kvm_sched_clock_read+0x5/0x11 [ 36.092508] ? __perf_event_task_sched_in+0x13d/0x13d [ 36.092513] cpu_function_call+0x47/0x69 [ 36.092516] ? perf_event_update_time+0x52/0x52 [ 36.092519] event_function_call+0x89/0x117 [ 36.092521] ? __perf_event_task_sched_in+0x13d/0x13d [ 36.092526] ? _perf_event_disable+0x4a/0x4a [ 36.092528] perf_event_for_each_child+0x3d/0x76 [ 36.092532] ? _perf_event_disable+0x4a/0x4a [ 36.092533] _perf_ioctl+0x564/0x590 [ 36.092537] ? __lock_release+0xd5/0x1b0 [ 36.092543] ? perf_event_ctx_lock_nested+0x8e/0xba [ 36.092547] perf_ioctl+0x42/0x5f [ 36.092551] vfs_ioctl+0x1e/0x2f [ 36.092554] __do_sys_ioctl+0x66/0x89 [ 36.092559] do_syscall_64+0x6d/0x84 [ 36.092563] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 36.092566] RIP: 0033:0x7fe7110f362b [ 36.092569] Code: 0f 1e fa 48 8b 05 5d b8 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 2d b8 2c 00 f7 d8 64 89 018 [ 36.092570] RSP: 002b:00007ffebb8e4b08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 36.092573] RAX: ffffffffffffffda RBX: 0000000000002400 RCX: 00007fe7110f362b [ 36.092575] RDX: 0000000000000000 RSI: 0000000000002400 RDI: 0000000000000013 [ 36.092576] RBP: 00007ffebb8e4b40 R08: 0000000000000001 R09: 000055c1db4a5b40 [ 36.092577] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 36.092579] R13: 000055c1db3b2a30 R14: 0000000000000000 R15: 0000000000000000 [ 36.092586] </TASK> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Yonghong Song <yhs@fb.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Stanislav Fomichev <sdf@google.com> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
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