On Fri, 23 Oct 2026 21:11:52 +0200 Jerome Marchand <[email protected]> wrote:
> I might have jumped to conclusion when I found the recursion and the > peculiarity of the powerpc local_t functions. I now think that the issue > lie in loop in powerpc arch_local_irq_restore() (goto again label). That > somehow it keeps replaying the soft interrupt when event tracing is on > and CONFIG_TRACE_IRQFLAGS is enabled. > > Here the output of the watchdog where we can see that most time is spent > in softirq: > > [257154.724054] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:107460] > [257154.724084] CPU#2 Utilization every 4000ms during lockup: > [257154.724099] #1: 0% system, 100% softirq, 1% hardirq, > 0% idle > [257154.724120] #2: 0% system, 100% softirq, 1% hardirq, > 0% idle > [257154.724141] #3: 0% system, 100% softirq, 1% hardirq, > 0% idle > [257154.724161] #4: 0% system, 100% softirq, 2% hardirq, > 0% idle > [257154.724182] #5: 0% system, 100% softirq, 1% hardirq, > 0% idle Yeah, the 100% softirq could be suspect. -- Steve > [257154.724203] Modules linked in: bonding tls rfkill binfmt_misc pseries_rng > ibmveth vmx_crypto vsock_loopback zram vmw_vsock_virtio_transport_common > vsock lz4hc_compress ibmvscsi scsi_transport_srp fuse i2c_dev > aes_gcm_p10_crypto crypto_simd cryptd > [257154.724399] irq event stamp: 0 > [257154.724410] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [257154.724471] hardirqs last disabled at (0): [<c0000000002b04b8>] > copy_process+0x1418/0x34e0 > [257154.724516] softirqs last enabled at (0): [<c0000000002b04b8>] > copy_process+0x1418/0x34e0 > [257154.724558] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [257154.724621] CPU: 2 UID: 0 PID: 107460 Comm: cat Tainted: P W > 7.2.0-rc4 #1 PREEMPT(lazy) > [257154.724654] Tainted: [P]=PROPRIETARY_MODULE, [W]=WARN > [257154.724665] Hardware name: IBM,8247-22L POWER8 (architected) 0x4b0201 > 0xf000004 of:IBM,FW860.81 (SV860_215) hv:phyp pSeries > [257154.724688] NIP: c00000000004f50c LR: c00000000004fc84 CTR: > 0000000000000000 > [257154.724708] REGS: c0000003affdfa68 TRAP: 0900 Tainted: P W > (7.2.0-rc4) > [257154.724727] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 24082800 > XER: 00000000 > [257154.724819] CFAR: 0000000000000000 IRQMASK: 0 > [257154.724819] GPR00: 0000000000000004 c0000003affdfa30 c000000003c8be00 > c0000003affdfa38 > [257154.724819] GPR04: 0000000000000000 0000000000000000 c0000003affdfc08 > 0000000000000000 > [257154.724819] GPR08: 0050244d39e48235 0000000000000049 fffffffffffffffc > 0000000000000002 > [257154.724819] GPR12: c000000000669520 c00000002ec9df00 c0000000060bbd40 > c00000000453e200 > [257154.724819] GPR16: c000000006d66b80 c000000004366af0 c00000000280b940 > 0000000000000007 > [257154.724819] GPR20: c000000006d61100 0000000000000007 c000000024832600 > 0000000000000103 > [257154.724819] GPR24: 0000000000160003 c00000000c573400 0000000000b5240f > c00000000e555fe8 > [257154.724819] GPR28: c00000000e53e108 0000000000000000 fcffffffffffffff > c00000002ec9df00 > [257154.725212] NIP [c00000000004f50c] __replay_soft_interrupts+0x6c/0x5f0 > [257154.725255] LR [c00000000004fc84] > arch_local_irq_restore.part.0+0x1f4/0x290 > [257154.725299] Call Trace: > [257154.725309] [c0000003affdfa30] [c00000000004f6dc] > __replay_soft_interrupts+0x23c/0x5f0 (unreliable) > [257154.725369] [c0000003affdfc30] [c00000000004fc84] > arch_local_irq_restore.part.0+0x1f4/0x290 > [257154.725423] [c0000003affdfc70] [c0000000006946dc] rb_commit+0x50c/0x620 > [257154.725468] [c0000003affdfcf0] [c0000000006992cc] > ring_buffer_unlock_commit+0x6c/0x3c0 > [257154.725514] [c0000003affdfd40] [c0000000006ae9c8] > trace_buffer_unlock_commit_regs+0x118/0x2a0 > [257154.725569] [c0000003affdfda0] [c0000000006aec74] > trace_event_buffer_commit+0x124/0x3e0 > [257154.725623] [c0000003affdfe10] [c0000000002cae68] > trace_event_raw_event_softirq+0xb8/0x170 > [257154.725675] [c0000003affdfe90] [c0000000002cc964] > handle_softirqs+0x864/0xc00 > [257154.725725] [c0000003affdffe0] [c00000000001cd1c] > do_softirq_own_stack+0x5c/0x90 > [257154.725777] [c000000040b279e0] [c00000000001cce4] > do_softirq_own_stack+0x24/0x90 > [257154.725827] [c000000040b27a10] [c0000000002c9ff8] > __irq_exit_rcu+0x458/0x560 > [257154.725876] [c000000040b27a60] [c0000000002cd72c] irq_exit+0x2c/0x90 > [257154.725924] [c000000040b27a90] [c00000000004fc88] > arch_local_irq_restore.part.0+0x1f8/0x290 > [257154.725978] [c000000040b27ad0] [c0000000006942b0] rb_commit+0xe0/0x620 > [257154.726021] [c000000040b27b50] [c0000000006992cc] > ring_buffer_unlock_commit+0x6c/0x3c0 > [257154.726067] [c000000040b27ba0] [c0000000006ae9c8] > trace_buffer_unlock_commit_regs+0x118/0x2a0 > [257154.726122] [c000000040b27c00] [c0000000006aec74] > trace_event_buffer_commit+0x124/0x3e0 > [257154.726175] [c000000040b27c70] [c000000000527c4c] > trace_event_raw_event_sys_exit+0xcc/0x180 > [257154.726222] [c000000040b27cf0] [c00000000052837c] > trace_syscall_exit+0xec/0x1e0 > [257154.726266] [c000000040b27d70] [c0000000000440e8] > syscall_exit_prepare+0xce8/0xde0 > [257154.726315] [c000000040b27e30] [c00000000000d6ac] > system_call_common+0x16c/0x2c4 > [257154.726368] ---- interrupt: c00 at 0x7fff9f08f8b0 > [257154.726421] NIP: 00007fff9f08f8b0 LR: 00007fff9f070a20 CTR: > 0000000000000000 > [257154.726440] REGS: c000000040b27e60 TRAP: 0c00 Tainted: P W > (7.2.0-rc4) > [257154.726458] MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> > CR: 24000802 XER: 00000000 > [257154.726582] IRQMASK: 0 > [257154.726582] GPR00: 000000000000007d 00007fffca534fd0 00007fff9f0b7f00 > 0000000000000000 > [257154.726582] GPR04: 0000000000010000 0000000000000001 0000000000000000 > 00007fff9f0b0b40 > [257154.726582] GPR08: 000000000005edb0 0000000000000000 0000000000000000 > 0000000000000000 > [257154.726582] GPR12: 0000000000000000 00007fff9f0ba580 00000001359c09b8 > 0000000000000000 > [257154.726582] GPR16: 00007fff9f0b3580 0000000080001000 00007fff9f0984c8 > 00007fffca535420 > [257154.726582] GPR20: 00007fff9f0b0b40 0000000000000000 00502449f00961a6 > 00007fff9f0b0cc8 > [257154.726582] GPR24: 0000000000000000 00007fff9f0b0cd0 00007fff9f0afbe8 > fffffffffffffff8 > [257154.726582] GPR28: 0000000000000000 000000000002fd2d 00007fff9f0b12f0 > 00007fffca535000 > [257154.726956] NIP [00007fff9f08f8b0] 0x7fff9f08f8b0 > [257154.727011] LR [00007fff9f070a20] 0x7fff9f070a20 > [257154.727063] ---- interrupt: c00 > [257154.727075] Code: 39200000 48178df1 60000000 7dbf6b78 386d0933 48b427e9 > 60000000 893f0933 38610038 61290040 993f0933 481176d1 <60000000> e9210140 > 7dbe6b78 386d0933
