Re: [PATCH v2 12/12] sched: Add ttwu_queue support for delayed tasks

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Peter,

On 7/3/2025 10:17 PM, Peter Zijlstra wrote:
> Also, I updated the git tree today, fixing a silly mistake. But I don't
> remember build failures here.

Running HammerDB + MySQL on baremetal results in a splats from
assert_clock_updated() ~10min into the run on peterz:sched/core at
commit 098ac7dd8a57 ("sched: Add ttwu_queue support for delayed
tasks") which I hope is the updated one.

I'm running with the following diff and haven't seen a splat yet
(slightly longer than 10min into HammerDB; still testing):

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9855121c2440..71ac0e7effeb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3871,7 +3871,7 @@ static int ttwu_delayed(struct rq *rq, struct task_struct *p, int wake_flags,
  	if (unlikely(rq != p_rq)) {
  		__task_rq_unlock(p_rq, rf);
  		rq_lock(rq, rf);
-		update_rq_clock(p_rq);
+		update_rq_clock(rq);
  	}
  
  	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
---

P.S. The full set of splats are as follows:

     ------------[ cut here ]------------
     WARNING: CPU: 141 PID: 8164 at kernel/sched/sched.h:1643 update_curr_se+0x5c/0x60
     Modules linked in: ...
     CPU: 141 UID: 1000 PID: 8164 Comm: mysqld Tainted: G     U              6.16.0-rc1-peterz-queue-098ac7+ #869 PREEMPT(voluntary)
     Tainted: [U]=USER
     Hardware name: Dell Inc. PowerEdge R6525/024PW1, BIOS 2.7.3 03/30/2022
     RIP: 0010:update_curr_se+0x5c/0x60
     Code: be a8 00 00 00 00 48 8d 96 80 02 00 00 74 07 48 8d 96 00 01 00 00 48 8b 4a 60 48 39 c1 48 0f 4c c8 48 89 4a 60 e9 1f af d5 ff <0f> 0b eb ae 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
     RSP: 0000:ffffd162151ffd30 EFLAGS: 00010097
     RAX: 0000000000000001 RBX: ffff8bb25c903500 RCX: ffffffff8afb3ca0
     RDX: 0000000000000009 RSI: ffff8bb25c903500 RDI: ffff8bf07e571b00
     RBP: ffff8bb25ea94400 R08: 0000014f849737b3 R09: 0000000000000009
     R10: 0000000000000001 R11: 0000000000000000 R12: ffff8bf07e571b00
     R13: ffff8bf07e571b00 R14: ffff8bb25c903500 R15: ffff8bb25ea94400
     FS:  00007fcd9e01f640(0000) GS:ffff8bf0f0858000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: 00007fcf3990c004 CR3: 0000000147f9900b CR4: 0000000000f70ef0
     PKRU: 55555554
     Call Trace:
      <TASK>
      update_curr+0x31/0x240
      enqueue_entity+0x2e/0x470
      enqueue_task_fair+0x122/0x850
      enqueue_task+0x88/0x1c0
      ttwu_do_activate+0x75/0x230
      sched_ttwu_pending+0x2b9/0x430
      __flush_smp_call_function_queue+0x140/0x420
      __sysvec_call_function_single+0x1c/0xb0
      sysvec_call_function_single+0x43/0xb0
      asm_sysvec_call_function_single+0x1a/0x20
     RIP: 0033:0x202a6de
     Code: 89 f1 4d 89 c4 4d 8d 44 24 01 41 0f b6 50 ff 49 8d 71 01 44 0f b6 5e ff 89 d0 44 29 d8 0f 85 01 02 00 00 48 89 ca 48 83 ea 01 <0f> 84 0c 02 00 00 4c 39 c7 75 c7 48 89 4d 80 4c 89 55 88 4c 89 4d
     RSP: 002b:00007fcd9e01a1f0 EFLAGS: 00000202
     RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000003
     RDX: 0000000000000002 RSI: 00007fc2684926c2 RDI: 00007fb96fe862b7
     RBP: 00007fcd9e01a270 R08: 00007fb96fe862b5 R09: 00007fc2684926c1
     R10: 0000000000000000 R11: 0000000000000000 R12: 00007fb96fe862b4
     R13: 0000000000000000 R14: 00000000ffffffff R15: 00007fcd9e01a310
      </TASK>
     ---[ end trace 0000000000000000 ]---

     ------------[ cut here ]------------
     WARNING: CPU: 141 PID: 8164 at kernel/sched/sched.h:1643 update_load_avg+0x6f7/0x780
     Modules linked in: ...
     CPU: 141 UID: 1000 PID: 8164 Comm: mysqld Tainted: G     U  W           6.16.0-rc1-peterz-queue-098ac7+ #869 PREEMPT(voluntary)
     Tainted: [U]=USER, [W]=WARN
     Hardware name: Dell Inc. PowerEdge R6525/024PW1, BIOS 2.7.3 03/30/2022
     RIP: 0010:update_load_avg+0x6f7/0x780
     Code: 42 f8 e9 c8 fa ff ff 39 c1 0f 42 c8 e9 4a fb ff ff 31 c0 45 31 c9 e9 cf fb ff ff 4c 8b a7 80 01 00 00 49 29 d4 e9 5a f9 ff ff <0f> 0b e9 42 f9 ff ff 69 d0 7e b6 00 00 e9 f4 fb ff ff 39 c2 0f 42
     RSP: 0000:ffffd162151ffd20 EFLAGS: 00010097
     RAX: ffff8bf07e571b00 RBX: ffff8bb25ea94400 RCX: 0000000000000041
     RDX: 0000000000000000 RSI: ffff8bb237533500 RDI: ffff8bb25ea94400
     RBP: ffff8bb237533500 R08: 000000000000132d R09: 0000000000000009
     R10: 0000000000000001 R11: 0000000000000000 R12: ffff8bf07e571b00
     R13: 0000000000000005 R14: ffff8bb25c903500 R15: ffff8bb25ea94400
     FS:  00007fcd9e01f640(0000) GS:ffff8bf0f0858000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: 00007fcf3990c004 CR3: 0000000147f9900b CR4: 0000000000f70ef0
     PKRU: 55555554
     Call Trace:
      <TASK>
      ? srso_alias_return_thunk+0x5/0xfbef5
      ? update_curr+0x1bd/0x240
      enqueue_entity+0x3e/0x470
      enqueue_task_fair+0x122/0x850
      enqueue_task+0x88/0x1c0
      ttwu_do_activate+0x75/0x230
      sched_ttwu_pending+0x2b9/0x430
      __flush_smp_call_function_queue+0x140/0x420
      __sysvec_call_function_single+0x1c/0xb0
      sysvec_call_function_single+0x43/0xb0
      asm_sysvec_call_function_single+0x1a/0x20
     RIP: 0033:0x202a6de
     Code: 89 f1 4d 89 c4 4d 8d 44 24 01 41 0f b6 50 ff 49 8d 71 01 44 0f b6 5e ff 89 d0 44 29 d8 0f 85 01 02 00 00 48 89 ca 48 83 ea 01 <0f> 84 0c 02 00 00 4c 39 c7 75 c7 48 89 4d 80 4c 89 55 88 4c 89 4d
     RSP: 002b:00007fcd9e01a1f0 EFLAGS: 00000202
     RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000003
     RDX: 0000000000000002 RSI: 00007fc2684926c2 RDI: 00007fb96fe862b7
     RBP: 00007fcd9e01a270 R08: 00007fb96fe862b5 R09: 00007fc2684926c1
     R10: 0000000000000000 R11: 0000000000000000 R12: 00007fb96fe862b4
     R13: 0000000000000000 R14: 00000000ffffffff R15: 00007fcd9e01a310
      </TASK>
     ---[ end trace 0000000000000000 ]---

     ------------[ cut here ]------------
     WARNING: CPU: 141 PID: 8164 at kernel/sched/sched.h:1643 enqueue_task+0x168/0x1c0
     Modules linked in: ...
     CPU: 141 UID: 1000 PID: 8164 Comm: mysqld Tainted: G     U  W           6.16.0-rc1-peterz-queue-098ac7+ #869 PREEMPT(voluntary)
     Tainted: [U]=USER, [W]=WARN
     Hardware name: Dell Inc. PowerEdge R6525/024PW1, BIOS 2.7.3 03/30/2022
     RIP: 0010:enqueue_task+0x168/0x1c0
     Code: ee 4c 89 e7 5d 41 5c 41 5d e9 24 d0 ff ff 41 f7 c5 00 02 00 00 0f 85 e4 fe ff ff e9 18 ff ff ff e8 3d f0 ff ff e9 b9 fe ff ff <0f> 0b eb ab 85 c0 74 10 80 fa 01 19 d2 83 e2 f6 83 c2 0e e9 7a ff
     RSP: 0000:ffffd162151ffe00 EFLAGS: 00010097
     RAX: 000000003cc00001 RBX: ffff8bf07e571b00 RCX: 0000000000000000
     RDX: 000000002721340a RSI: 0000014fabb84509 RDI: ffff8bf07e55cd80
     RBP: ffff8bb237533480 R08: 0000014fabb84509 R09: 0000000000000001
     R10: 0000000000000001 R11: 0000000000000000 R12: ffff8bf07e571b00
     R13: 0000000000000009 R14: ffffd162151ffe90 R15: 0000000000000008
     FS:  00007fcd9e01f640(0000) GS:ffff8bf0f0858000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: 00007fcf3990c004 CR3: 0000000147f9900b CR4: 0000000000f70ef0
     PKRU: 55555554
     Call Trace:
      <TASK>
      ttwu_do_activate+0x75/0x230
      sched_ttwu_pending+0x2b9/0x430
      __flush_smp_call_function_queue+0x140/0x420
      __sysvec_call_function_single+0x1c/0xb0
      sysvec_call_function_single+0x43/0xb0
      asm_sysvec_call_function_single+0x1a/0x20
     RIP: 0033:0x202a6de
     Code: 89 f1 4d 89 c4 4d 8d 44 24 01 41 0f b6 50 ff 49 8d 71 01 44 0f b6 5e ff 89 d0 44 29 d8 0f 85 01 02 00 00 48 89 ca 48 83 ea 01 <0f> 84 0c 02 00 00 4c 39 c7 75 c7 48 89 4d 80 4c 89 55 88 4c 89 4d
     RSP: 002b:00007fcd9e01a1f0 EFLAGS: 00000202
     RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000003
     RDX: 0000000000000002 RSI: 00007fc2684926c2 RDI: 00007fb96fe862b7
     RBP: 00007fcd9e01a270 R08: 00007fb96fe862b5 R09: 00007fc2684926c1
     R10: 0000000000000000 R11: 0000000000000000 R12: 00007fb96fe862b4
     R13: 0000000000000000 R14: 00000000ffffffff R15: 00007fcd9e01a310
      </TASK>
     ---[ end trace 0000000000000000 ]---

-- 
Thanks and Regards,
Prateek