On Tue, Jan 28, 2025 at 03:34:50PM +0100, Uladzislau Rezki wrote: > On Tue, Jan 28, 2025 at 04:41:16AM -0800, Paul E. McKenney wrote: > > On Tue, Jan 28, 2025 at 01:17:34PM +0100, Uladzislau Rezki wrote: > > > > > > with 4 CPUs inside VM :) > > > > > > > > > > > And when running 16 instances with 4 CPUs each i can reproduce the > > > > > splat which has been reported: > > > > > > > > > > tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --configs \ > > > > > '16*TREE05' --memory 10G --bootargs 'rcutorture.fwd_progress=1' \ > > > > > --kconfig "CONFIG_NR_CPUS=4" > > > > > > > > > > <snip> > > > > > ... > > > > > [ 0.595251] ------------[ cut here ]------------ > > > > > [ 0.595867] A full grace period is not passed yet: 0 > > > > > [ 0.595875] WARNING: CPU: 1 PID: 16 at kernel/rcu/tree.c:1617 rcu_sr_normal_complete+0xa9/0xc0 > > > > > [ 0.598248] Modules linked in: > > > > > [ 0.598649] CPU: 1 UID: 0 PID: 16 Comm: rcu_preempt Not tainted 6.13.0-02530-g8950af6a11ff #261 > > > > > [ 0.599248] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > > > > [ 0.600248] RIP: 0010:rcu_sr_normal_complete+0xa9/0xc0 > > > > > [ 0.600913] Code: 48 29 c2 48 8d 04 0a ba 03 00 00 00 48 39 c2 79 0c 48 83 e8 04 48 c1 e8 02 48 8d 70 02 48 c7 c7 20 e9 33 b5 e8 d8 03 f4 ff 90 <0f> 0b 90 90 48 8d 7b 10 5b e9 f9 38 fb ff 66 0f 1f 84 00 00 00 00 > > > > > [ 0.603249] RSP: 0018:ffffadad0008be60 EFLAGS: 00010282 > > > > > [ 0.603925] RAX: 0000000000000000 RBX: ffffadad00013d10 RCX: 00000000ffffdfff > > > > > [ 0.605247] RDX: 0000000000000000 RSI: ffffadad0008bd10 RDI: 0000000000000001 > > > > > [ 0.606247] RBP: 0000000000000000 R08: 0000000000009ffb R09: 00000000ffffdfff > > > > > [ 0.607248] R10: 00000000ffffdfff R11: ffffffffb56789a0 R12: 0000000000000005 > > > > > [ 0.608247] R13: 0000000000031a40 R14: fffffffffffffb74 R15: 0000000000000000 > > > > > [ 0.609250] FS: 0000000000000000(0000) GS:ffff9081f5c80000(0000) knlGS:0000000000000000 > > > > > [ 0.610249] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > [ 0.611248] CR2: 0000000000000000 CR3: 00000002f024a000 CR4: 00000000000006f0 > > > > > [ 0.612249] Call Trace: > > > > > [ 0.612574] <TASK> > > > > > [ 0.612854] ? __warn+0x8c/0x190 > > > > > [ 0.613248] ? rcu_sr_normal_complete+0xa9/0xc0 > > > > > [ 0.613840] ? report_bug+0x164/0x190 > > > > > [ 0.614248] ? handle_bug+0x54/0x90 > > > > > [ 0.614705] ? exc_invalid_op+0x17/0x70 > > > > > [ 0.615248] ? asm_exc_invalid_op+0x1a/0x20 > > > > > [ 0.615797] ? rcu_sr_normal_complete+0xa9/0xc0 > > > > > [ 0.616248] rcu_gp_cleanup+0x403/0x5a0 > > > > > [ 0.616248] ? __pfx_rcu_gp_kthread+0x10/0x10 > > > > > [ 0.616818] rcu_gp_kthread+0x136/0x1c0 > > > > > [ 0.617249] kthread+0xec/0x1f0 > > > > > [ 0.617664] ? __pfx_kthread+0x10/0x10 > > > > > [ 0.618156] ret_from_fork+0x2f/0x50 > > > > > [ 0.618728] ? __pfx_kthread+0x10/0x10 > > > > > [ 0.619216] ret_from_fork_asm+0x1a/0x30 > > > > > [ 0.620251] </TASK> > > > > > ... > > > > > <snip> > > > > > > > > > > Linus tip-tree, HEAD is c4b9570cfb63501638db720f3bee9f6dfd044b82 > > > > > > > > Very good! And of course, the next question is "does going to _full() > > > > make the problem go away?" ;-) > > > > > > > Yes does its job if i apply: > > > > > > https://lore.kernel.org/rcu/00900afe-ac4e-4362-a3f9-d65f2c9dcd9a@paulmck-laptop/T/#m5d9263f3825d3170c044beedbae741717702d4aa > > > > > > after that i am not able to reproduce the warning anymore. Tested over > > > night. Without it, i can reproduce it pretty easy :) > > > > Thank you, and good to hear!!! > > > > May I add your Tested-by to that patch? > > > Sure. > > Tested-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Thank you! I will apply this on my next rebase. > One question, we discussed that it is worth to print seq-delta > in case of warning. Whereas a newly patch does do it and just > emits a plain text. > > I can send a separate patch or modify this one? A separate patch would be best. If it helps, one possible set of functions to model this on is rcutorture_format_gp_seqs() on the "dev" branch of -rcu: 9357e5aecb63 ("rcutorture: Include grace-period sequence numbers in failure/close-call") This has the needed #ifdefs and the different implementations for Tree and Tiny RCU. Thanx, Paul
