Hi, I am receiving an error from the RCU stall detector when using ebpf. I have managed to reproduce it on the 6.9.4 kernel (running inside qemu_system_x86-64), using the files attached. The exact output is: [ 21.742355] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 21.742643] rcu: (detected by 0, t=21002 jiffies, g=-1039, q=8 ncpus=1) [ 21.742899] rcu: All QSes seen, last rcu_preempt kthread activity 21002 (4294688977-4294667975), jiffies_till_next_fqs=3, root ->qsmask 0x0 [ 21.743358] rcu: rcu_preempt kthread starved for 21002 jiffies! g-1039 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 [ 21.743738] rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. [ 21.744074] rcu: RCU grace-period kthread stack dump: [ 21.744263] task:rcu_preempt state:R running task stack:15544 pid:15 tgid:15 ppid:2 flags:0x00004000 [ 21.744677] Call Trace: [ 21.744778] <TASK> [ 21.744866] __schedule+0x309/0x890 [ 21.745018] ? __pfx_rcu_gp_kthread+0x10/0x10 [ 21.745194] schedule+0x2b/0xe0 [ 21.745323] schedule_timeout+0x86/0x160 [ 21.745466] ? __pfx_process_timeout+0x10/0x10 [ 21.745626] rcu_gp_fqs_loop+0x113/0x670 [ 21.745767] rcu_gp_kthread+0x19b/0x240 [ 21.745904] kthread+0xd2/0x100 [ 21.746019] ? __pfx_kthread+0x10/0x10 [ 21.746153] ret_from_fork+0x2f/0x50 [ 21.746283] ? __pfx_kthread+0x10/0x10 [ 21.746416] ret_from_fork_asm+0x1a/0x30 [ 21.746559] </TASK> [ 21.746640] rcu: Stack dump where RCU GP kthread last ran: [ 21.746833] CPU: 0 PID: 56 Comm: exploit Not tainted 6.9.4 #1 [ 21.747035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 21.747335] RIP: 0010:___bpf_prog_run+0x29/0x20a0 [ 21.747524] Code: 90 41 55 41 54 45 31 e4 55 48 89 fd 53 48 89 f3 0f b6 33 40 0f b6 d6 89 f0 48 8b 14 d5 00 7f 41 a0 e9 eb e9 da 00 f3 0f 1e fa <f3> 0f 1e fa 8b 53 04 83 fa 51 0f 84 07 1f 00 00 0f 8f 62 16 00 00 [ 21.748243] RSP: 0018:ffff9252801bfa68 EFLAGS: 00000213 [ 21.748450] RAX: 00000000000000c3 RBX: ffff9252800350b0 RCX: 00000000ffffff8d [ 21.748732] RDX: ffffffff9edd48d9 RSI: 00000000000000c3 RDI: ffff9252801bfa90 [ 21.749012] RBP: ffff9252801bfa90 R08: ffff8dc381261e00 R09: ffff8dc381261e00 [ 21.749292] R10: ffff8dc381bbe000 R11: ffff8dc3811f0000 R12: 0000000000000000 [ 21.749572] R13: 0000000000000001 R14: ffff8dc381bbe400 R15: 0000000000000001 [ 21.749854] FS: 00007fb818a03680(0000) GS:ffff8dc3fd800000(0000) knlGS:0000000000000000 [ 21.750170] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.750397] CR2: 0000564d89dca2a8 CR3: 0000000001bbc000 CR4: 00000000000006f0 [ 21.750678] Call Trace: [ 21.750779] <IRQ> [ 21.750864] ? rcu_check_gp_kthread_starvation+0x108/0x1a0 [ 21.751082] ? rcu_sched_clock_irq+0xc47/0xf50 [ 21.751260] ? timekeeping_update+0xab/0x280 [ 21.751433] ? timekeeping_advance+0x372/0x590 [ 21.751612] ? update_process_times+0x68/0xa0 [ 21.751786] ? tick_nohz_handler+0x110/0x190 [ 21.751958] ? __pfx_tick_nohz_handler+0x10/0x10 [ 21.752143] ? __hrtimer_run_queues+0x10d/0x2a0 [ 21.752324] ? hrtimer_interrupt+0xfe/0x240 [ 21.752491] ? __sysvec_apic_timer_interrupt+0x53/0x140 [ 21.752702] ? sysvec_apic_timer_interrupt+0x6b/0x80 [ 21.752901] </IRQ> [ 21.752989] <TASK> [ 21.753077] ? asm_sysvec_apic_timer_interrupt+0x1a/0x20 [ 21.753287] ? ___bpf_prog_run+0x29/0x20a0 [ 21.753451] ? ___bpf_prog_run+0x29/0x20a0 [ 21.753614] ? ___bpf_prog_run+0x29/0x20a0 [ 21.753778] __bpf_prog_run448+0x46/0x70 [ 21.753936] ? place_entity+0x14/0xf0 [ 21.754085] ? __alloc_pages+0x1bb/0x1020 [ 21.754247] ? kmem_cache_alloc_node+0x45/0x260 [ 21.754429] ? wakeup_preempt+0x5c/0x70 [ 21.754583] ? kmalloc_reserve+0x89/0xe0 [ 21.754741] ? kmalloc_reserve+0x89/0xe0 [ 21.754898] ? __alloc_skb+0xd7/0x1a0 [ 21.755046] ? security_sock_rcv_skb+0x29/0x40 [ 21.755225] sk_filter_trim_cap+0xaf/0x200 [ 21.755389] ? skb_copy_datagram_from_iter+0x59/0x1e0 [ 21.755590] unix_dgram_sendmsg+0x392/0xba0 [ 21.755759] ? remove_wait_queue+0x11/0x50 [ 21.755923] sock_write_iter+0x18f/0x1a0 [ 21.756081] vfs_write+0x37e/0x430 [ 21.756222] ksys_write+0xaa/0xe0 [ 21.756354] do_syscall_64+0xa8/0x1b0 [ 21.756502] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 21.756706] RIP: 0033:0x7fb81891c4e0 [ 21.756851] Code: 69 0d 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 80 3d 89 ee 0d 00 00 74 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 48 83 ec 28 48 89 [ 21.757571] RSP: 002b:00007ffd045da728 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 [ 21.757867] RAX: ffffffffffffffda RBX: 00007ffd045da978 RCX: 00007fb81891c4e0 [ 21.758147] RDX: 0000000000000001 RSI: 00007ffd045da73f RDI: 0000000000000005 [ 21.758427] RBP: 00007ffd045da860 R08: 000000000000ee08 R09: 0000000000000001 [ 21.758706] R10: 00007fb818828278 R11: 0000000000000202 R12: 0000000000000000 [ 21.758986] R13: 00007ffd045da988 R14: 00007fb818a3c000 R15: 0000564d75188dd8 [ 21.759266] </TASK> Apologies if this is not a relevant bug that needs fixing, and any mistakes in etiquette. Please let me know any additional information needed. Thanks
Attachment:
repro.tar.xz
Description: application/xz
