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Content-Language: en-US From: Tony Rodriguez To: Thorsten Leemhuis Cc: John Paul Adrian Glaubitz , Greg KH , Linus Torvalds , Linux kernel regressions list , LKML , Thomas Gleixner References: <1c165caf-36b4-4673-97fd-ed86bef17b88@leemhuis.info> <3332123b-9e11-4895-9ab3-1707fba5815c@gmail.com> In-Reply-To: <3332123b-9e11-4895-9ab3-1707fba5815c@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Just confirmed on my end today.  This regression also impacts both SPARC64 S7-2 and SPARC64 T7-1 on v7.0.4 and v7.1-rc2 as well. Different systems using the same exact kernels. ** Please see points (A1) (A2) (B1) (B2) Once again, I am not experiencing such issues when "my patch" (link below) is added to address this regression. https://github.com/sparclinux/issues/issues/79#issuecomment-4362173884 Output demonstrating issues for SPARC64 S7-2 and T7-1 systems (without my regression patch): PS - On May 2nd, 2026 at 9:42 PM: I also sent an email to Thomas Gleixner regarding this issue.  I will be happy to validate any patches from your end regarding this issue, as time permits me to do so. Best regards, Tony Rodriguez  A1) SPARC64 S7-2: Kernel v7.1.0-rc2 uname -a Linux s7t7-debian-test 7.1.0-rc2-test01 #1 SMP Fri May  8 10:02:12 PDT 2026 sparc64 GNU/Linux cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-7.1.0-rc2-test01 root=UUID=ce937a4b-126a-41bd-a54b-03a424421086 ro console=ttyHV0,9600n81 systemd.log_level=info systemd.show_status=1 systemd.journald.forward_to_console=0 plymouth.enable=0 quiet [  243.267359] INFO: task kworker/u512:1:706 blocked for more than 120 seconds. [  243.281208]       Not tainted 7.1.0-rc2-test01 #1 [  243.290583] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  243.306349] INFO: task kworker/127:1:714 blocked for more than 120 seconds. [  243.320106]       Not tainted 7.1.0-rc2-test01 #1 [  243.329476] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  364.099350] INFO: task kworker/u512:1:706 blocked for more than 241 seconds. [  364.113199]       Not tainted 7.1.0-rc2-test01 #1 [  364.122585] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  364.138328] INFO: task kworker/127:1:714 blocked for more than 241 seconds. [  364.152086]       Not tainted 7.1.0-rc2-test01 #1 [  364.161470] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  485.295360] INFO: task kworker/u512:1:706 blocked for more than 362 seconds. [  485.309209]       Not tainted 7.1.0-rc2-test01 #1 [  485.318581] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  485.334345] INFO: task kworker/127:1:714 blocked for more than 362 seconds. [  485.348099]       Not tainted 7.1.0-rc2-test01 #1 [  485.357467] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  726.849598] INFO: task kworker/u512:1:706 blocked for more than 604 seconds. [  726.863444]       Not tainted 7.1.0-rc2-test01 #1 [  726.872832] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  726.888573] INFO: task kworker/127:1:714 blocked for more than 604 seconds. [  726.902340]       Not tainted 7.1.0-rc2-test01 #1 [  726.911708] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. sudo dmesg | grep -iE block | grep -iE worker [  243.267359] INFO: task kworker/u512:1:706 blocked for more than 120 seconds. [  243.306349] INFO: task kworker/127:1:714 blocked for more than 120 seconds. [  364.099350] INFO: task kworker/u512:1:706 blocked for more than 241 seconds. [  364.138328] INFO: task kworker/127:1:714 blocked for more than 241 seconds. [  485.295360] INFO: task kworker/u512:1:706 blocked for more than 362 seconds. [  485.334345] INFO: task kworker/127:1:714 blocked for more than 362 seconds. [  605.849474] INFO: task kworker/u512:1:706 blocked for more than 483 seconds. [  605.888461] INFO: task kworker/127:1:714 blocked for more than 483 seconds. sudo poweroff or sudo reboot NOTE(S): Random hangs during startup. Also, hangs during shutdown/reboot process. ------------------------------------------------------------------------------------------- A2) SPARC64 S7-2: Kernel v7.0.4 [  OK  ] Finished e2scrub_reap.service - Remove Stale Online ext4 Metadata Check Snapshots. Debian GNU/Linux forky/sid s7t7-debian-test ttyHV0 s7t7-debian-test login: tonyr Password: Linux s7t7-debian-test 7.0.4-test01 #1 SMP Fri May  8 09:27:58 PDT 2026 sparc64 [...] Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. login: timed [  114.687722] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  114.699319] rcu:     67-...!: (240 GPs behind) idle=e9c0/0/0x0 softirq=174/174 fqs=0 (false positive?) [  114.717370] rcu:     102-...!: (73 GPs behind) idle=77e0/0/0x0 softirq=286/287 fqs=0 (false positive?) [  114.735419] rcu:     111-...!: (52 GPs behind) idle=11d8/0/0x0 softirq=860/861 fqs=0 (false positive?) [  114.753489] rcu:     (detected by 11, t=5268 jiffies, g=4457, q=528 ncpus=128) [  114.767628] rcu: rcu_sched kthread timer wakeup didn't happen for 5270 jiffies! g4457 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  114.789647] rcu:     Possible timer handling issue on cpu=105 timer-softirq=98 [  114.803535] rcu: rcu_sched kthread starved for 5280 jiffies! g4457 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=105 [  114.824201] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  114.842080] rcu: RCU grace-period kthread stack dump: [  114.852221] rcu: Stack dump where RCU GP kthread last ran: [  135.867723] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  135.879326] rcu:     65-...!: (1 GPs behind) idle=35b0/0/0x0 softirq=483/484 fqs=0 (false positive?) [  135.897024] rcu:     67-...!: (241 GPs behind) idle=ecc0/0/0x0 softirq=174/174 fqs=0 (false positive?) [  135.915082] rcu:     102-...!: (74 GPs behind) idle=7800/0/0x0 softirq=286/287 fqs=0 (false positive?) [  135.933123] rcu:     111-...!: (53 GPs behind) idle=1238/0/0x0 softirq=860/861 fqs=0 (false positive?) [  135.951184] rcu:     (detected by 64, t=5272 jiffies, g=4461, q=752 ncpus=128) [  135.965398] rcu: rcu_sched kthread timer wakeup didn't happen for 5275 jiffies! g4461 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  135.987393] rcu:     Possible timer handling issue on cpu=105 timer-softirq=98 [  136.001287] rcu: rcu_sched kthread starved for 5285 jiffies! g4461 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=105 [  136.021944] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  136.039829] rcu: RCU grace-period kthread stack dump: [  136.049971] rcu: Stack dump where RCU GP kthread last ran: NOTE(S): Unable to login and random hangs during system startup. ------------------------------------------------------------------------- B1) SPARC64 T7-1: Kernel v7.1.0-rc2 lscpu;uname -a Architecture:          sparc64   CPU op-mode(s):      32-bit, 64-bit   Byte Order:          Big Endian CPU(s):                256   On-line CPU(s) list: 0-255 Model name:            SPARC-M7   Thread(s) per core:  8   Core(s) per socket:  32   Socket(s):           1   Flags:               sun4v Caches (sum of all):   L1d:                 4 MiB (256 instances)   L1i:                 4 MiB (256 instances)   L2:                  64 MiB (256 instances) Linux s7t7-debian-test 7.1.0-rc2-test01 #1 SMP Fri May  8 10:02:12 PDT 2026 sparc64 GNU/Linux   526.766867] rcu:     8-...!: (806 GPs behind) idle=069c/0/0x1 softirq=682/682 fqs=0 [  526.781618] rcu:     22-...!: (0 ticks this GP) idle=7b40/0/0x0 softirq=739/739 fqs=0 (false positive?) [  526.799841] rcu:     89-...!: (770 GPs behind) idle=7800/0/0x0 softirq=270/273 fqs=0 (false positive?) [  526.817901] rcu:     112-...!: (225 GPs behind) idle=c0c8/0/0x0 softirq=193/193 fqs=0 (false positive?) [  526.836131] rcu:     189-...!: (0 ticks this GP) idle=8ef0/0/0x0 softirq=1016/1016 fqs=0 (false positive?) [  526.854885] rcu:     204-...!: (0 ticks this GP) idle=5d20/0/0x0 softirq=774/774 fqs=0 (false positive?) [  526.873278] rcu:     219-...!: (225 GPs behind) idle=d580/0/0x0 softirq=605/607 fqs=0 (false positive?) [  526.891508] rcu:     226-...!: (233 GPs behind) idle=ec08/0/0x0 softirq=1189/1190 fqs=0 (false positive?) [  526.910079] rcu:     (detected by 157, t=5289 jiffies, g=5989, q=5339 ncpus=256) [  526.924916] rcu: rcu_sched kthread timer wakeup didn't happen for 5295 jiffies! g5989 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  526.946930] rcu:     Possible timer handling issue on cpu=94 timer-softirq=279 [  526.960818] rcu: rcu_sched kthread starved for 5302 jiffies! g5989 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=94 [  526.981300] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  526.999182] rcu: RCU grace-period kthread stack dump: [  527.009301] rcu: Stack dump where RCU GP kthread last ran: [  548.035259] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  548.046861] rcu:     8-...!: (807 GPs behind) idle=071c/0/0x1 softirq=682/682 fqs=0 [  548.061608] rcu:     17-...!: (0 ticks this GP) idle=00e8/0/0x0 softirq=812/812 fqs=0 (false positive?) [  548.079831] rcu:     84-...!: (0 ticks this GP) idle=d2b0/0/0x0 softirq=797/797 fqs=0 (false positive?) [  548.098070] rcu:     89-...!: (771 GPs behind) idle=7be8/0/0x0 softirq=270/273 fqs=0 (false positive?) [  548.116122] rcu:     112-...!: (226 GPs behind) idle=c110/0/0x0 softirq=193/193 fqs=0 (false positive?) [  548.134342] rcu:     185-...!: (0 ticks this GP) idle=45b8/0/0x0 softirq=871/871 fqs=0 (false positive?) [  548.152759] rcu:     193-...!: (0 ticks this GP) idle=1758/0/0x0 softirq=1520/1520 fqs=0 (false positive?) [  548.171509] rcu:     205-...!: (0 ticks this GP) idle=1e98/0/0x0 softirq=852/852 fqs=0 (false positive?) [  548.189893] rcu:     219-...!: (226 GPs behind) idle=d5c8/0/0x0 softirq=605/607 fqs=0 (false positive?) [  548.208128] rcu:     226-...!: (234 GPs behind) idle=eff0/0/0x0 softirq=1189/1190 fqs=0 (false positive?) [  548.226699] rcu:     (detected by 115, t=5300 jiffies, g=5993, q=5539 ncpus=256) [  548.241699] rcu: rcu_sched kthread timer wakeup didn't happen for 5303 jiffies! g5993 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  548.263704] rcu:     Possible timer handling issue on cpu=94 timer-softirq=279 [  548.277593] rcu: rcu_sched kthread starved for 5311 jiffies! g5993 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=94 [  548.298081] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  548.315971] rcu: RCU grace-period kthread stack dump: [  548.326084] rcu: Stack dump where RCU GP kthread last ran: [  569.343268] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  569.354868] rcu:     8-...!: (808 GPs behind) idle=07ac/0/0x1 softirq=682/682 fqs=0 [  569.369617] rcu:     89-...!: (772 GPs behind) idle=8518/0/0x0 softirq=270/273 fqs=0 (false positive?) [  569.387674] rcu:     112-...!: (227 GPs behind) idle=c168/0/0x0 softirq=193/193 fqs=0 (false positive?) [  569.405894] rcu:     219-...!: (227 GPs behind) idle=d620/0/0x0 softirq=605/607 fqs=0 (false positive?) [  569.424128] rcu:     226-...!: (235 GPs behind) idle=f920/0/0x0 softirq=1189/1190 fqs=0 (false positive?) [  569.442700] rcu:     (detected by 76, t=5276 jiffies, g=5997, q=5665 ncpus=256) [  569.457146] rcu: rcu_sched kthread timer wakeup didn't happen for 5278 jiffies! g5997 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  569.479149] rcu:     Possible timer handling issue on cpu=94 timer-softirq=279 [  569.493043] rcu: rcu_sched kthread starved for 5285 jiffies! g5997 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=94 [  569.513534] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  569.531419] rcu: RCU grace-period kthread stack dump: [  569.541536] rcu: Stack dump where RCU GP kthread last ran: [  590.563260] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  590.574870] rcu:     8-...!: (809 GPs behind) idle=0824/0/0x1 softirq=682/682 fqs=0 [  590.589618] rcu:     89-...!: (773 GPs behind) idle=8850/0/0x0 softirq=270/273 fqs=0 (false positive?) [  590.607682] rcu:     112-...!: (228 GPs behind) idle=c198/0/0x0 softirq=193/193 fqs=0 (false positive?) [  590.625904] rcu:     195-...!: (0 ticks this GP) idle=7178/0/0x0 softirq=1038/1038 fqs=0 (false positive?) [  590.644660] rcu:     207-...!: (0 ticks this GP) idle=9440/0/0x0 softirq=809/809 fqs=0 (false positive?) [  590.663056] rcu:     219-...!: (228 GPs behind) idle=d650/0/0x0 softirq=605/607 fqs=0 (false positive?) [  590.681285] rcu:     226-...!: (236 GPs behind) idle=fc78/0/0x0 softirq=1189/1190 fqs=0 (false positive?) [  590.699859] rcu:     (detected by 138, t=5286 jiffies, g=6001, q=5524 ncpus=256) [  590.714623] rcu: rcu_sched kthread timer wakeup didn't happen for 5288 jiffies! g6001 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  590.736635] rcu:     Possible timer handling issue on cpu=94 timer-softirq=279 [  590.750524] rcu: rcu_sched kthread starved for 5296 jiffies! g6001 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=94 [  590.771021] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  590.788903] rcu: RCU grace-period kthread stack dump: [  590.799012] rcu: Stack dump where RCU GP kthread last ran: [  606.363275] INFO: task kworker/u1024:0:12 blocked for more than 483 seconds. [  606.377139]       Tainted: G        W  7.1.0-rc2-test01 #1 [  606.389636] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  611.823259] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  611.834860] rcu:     8-...!: (810 GPs behind) idle=08bc/0/0x1 softirq=682/682 fqs=0 [  611.849612] rcu:     89-...!: (774 GPs behind) idle=91a8/0/0x0 softirq=270/273 fqs=0 (false positive?) [  611.867665] rcu:     112-...!: (229 GPs behind) idle=c1d8/0/0x0 softirq=193/193 fqs=0 (false positive?) [  611.885887] rcu:     205-...!: (0 ticks this GP) idle=2160/0/0x0 softirq=865/865 fqs=0 (false positive?) [  611.904290] rcu:     219-...!: (229 GPs behind) idle=d690/0/0x0 softirq=605/607 fqs=0 (false positive?) [  611.922525] rcu:     226-...!: (237 GPs behind) idle=05e0/0/0x0 softirq=1189/1190 fqs=0 (false positive?) [  611.941095] rcu:     (detected by 166, t=5283 jiffies, g=6005, q=5522 ncpus=256) [  611.955789] rcu: rcu_sched kthread timer wakeup didn't happen for 5285 jiffies! g6005 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  611.977793] rcu:     Possible timer handling issue on cpu=94 timer-softirq=279 [  611.991685] rcu: rcu_sched kthread starved for 5292 jiffies! g6005 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=94 [  612.012174] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  612.030060] rcu: RCU grace-period kthread stack dump: [  612.040180] rcu: Stack dump where RCU GP kthread last ran: r[  727.195272] INFO: task kworker/u1024:0:12 blocked for more than 604 seconds. [  727.209134]       Tainted: G        W  7.1.0-rc2-test01 #1 [  727.221628] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. NOTE(S): Random hangs and same messages as S7-2. Takes about 15 minutes to see the messages. --------------------------------------------------------- B2) SPARC64 T7-1 Kernel v7.0.4 [  OK  ] Finished e2scrub_reap.service - Remove Stale Online ext4 Metadata Check Snapshots. Debian GNU/Linux forky/sid s7t7-debian-test ttyHV0 s7t7-debian-test login: tonyr Password: Linux s7t7-debian-test 7.0.4-test01 #1 SMP Fri May  8 09:27:58 PDT 2026 sparc64 [..] Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. [   79.468871] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [   79.480483] rcu:     114-...!: (424 GPs behind) idle=8760/0/0x0 softirq=126/126 fqs=0 (false positive?) [   79.498713] rcu:     (detected by 90, t=5259 jiffies, g=3769, q=818 ncpus=256) [   79.512702] rcu: rcu_sched kthread timer wakeup didn't happen for 5260 jiffies! g3769 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [   79.534808] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [   79.548516] rcu: rcu_sched kthread starved for 5267 jiffies! g3769 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [   79.568838] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [   79.586709] rcu: RCU grace-period kthread stack dump: [   79.596867] rcu: Stack dump where RCU GP kthread last ran: [  100.612874] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  100.624477] rcu:     114-...!: (425 GPs behind) idle=88f0/0/0x0 softirq=126/126 fqs=0 (false positive?) [  100.642709] rcu:     157-...!: (0 ticks this GP) idle=4c08/0/0x0 softirq=122/122 fqs=0 (false positive?) [  100.661106] rcu:     (detected by 3, t=5264 jiffies, g=3773, q=1046 ncpus=256) [  100.675155] rcu: rcu_sched kthread timer wakeup didn't happen for 5265 jiffies! g3773 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  100.697211] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  100.710934] rcu: rcu_sched kthread starved for 5276 jiffies! g3773 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  100.731244] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  100.749125] rcu: RCU grace-period kthread stack dump: [  100.759255] rcu: Stack dump where RCU GP kthread last ran: login: ti[  121.776867] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  121.788467] rcu:     114-...!: (426 GPs behind) idle=8a20/0/0x0 softirq=126/126 fqs=0 (false positive?) [  121.806703] rcu:     (detected by 3, t=5259 jiffies, g=3777, q=1267 ncpus=256) [  121.820664] rcu: rcu_sched kthread timer wakeup didn't happen for 5260 jiffies! g3777 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  121.842799] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  121.856521] rcu: rcu_sched kthread starved for 5271 jiffies! g3777 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  121.876836] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  121.894717] rcu: RCU grace-period kthread stack dump: [  121.904824] rcu: Stack dump where RCU GP kthread last ran: [  142.920877] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  142.932481] rcu:     114-...!: (427 GPs behind) idle=8b98/0/0x0 softirq=126/126 fqs=0 (false positive?) [  142.950709] rcu:     158-...!: (1 GPs behind) idle=5220/0/0x0 softirq=142/148 fqs=0 (false positive?) [  142.968586] rcu:     (detected by 122, t=5260 jiffies, g=3781, q=722 ncpus=256) [  142.982808] rcu: rcu_sched kthread timer wakeup didn't happen for 5265 jiffies! g3781 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  143.004857] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  143.018583] rcu: rcu_sched kthread starved for 5273 jiffies! g3781 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  143.038893] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  143.056761] rcu: RCU grace-period kthread stack dump: [  143.066898] rcu: Stack dump where RCU GP kthread last ran: [  164.084863] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  164.096463] rcu:     14-...!: (0 ticks this GP) idle=56b0/0/0x0 softirq=165/165 fqs=0 (false positive?) [  164.114695] rcu:     114-...!: (428 GPs behind) idle=8ed0/0/0x0 softirq=126/126 fqs=0 (false positive?) [  164.132916] rcu:     (detected by 96, t=5264 jiffies, g=3785, q=750 ncpus=256) [  164.146969] rcu: rcu_sched kthread timer wakeup didn't happen for 5265 jiffies! g3785 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  164.169019] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  164.182728] rcu: rcu_sched kthread starved for 5276 jiffies! g3785 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  164.203055] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  164.220922] rcu: RCU grace-period kthread stack dump: [  164.231039] rcu: Stack dump where RCU GP kthread last ran: [  185.248867] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  185.260468] rcu:     21-...!: (0 ticks this GP) idle=36c8/0/0x0 softirq=154/154 fqs=0 (false positive?) [  185.278684] rcu:     114-...!: (429 GPs behind) idle=8f68/0/0x0 softirq=126/126 fqs=0 (false positive?) [  185.296922] rcu:     (detected by 116, t=5264 jiffies, g=3789, q=760 ncpus=256) [  185.311140] rcu: rcu_sched kthread timer wakeup didn't happen for 5265 jiffies! g3789 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  185.333205] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  185.346918] rcu: rcu_sched kthread starved for 5276 jiffies! g3789 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  185.367224] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  185.385113] rcu: RCU grace-period kthread stack dump: [  185.395229] rcu: Stack dump where RCU GP kthread last ran:   OK  ] Reached target network-online.target - Network is Online. [  OK  ] Started anacron.service - Run anacron jobs. [  OK  ] Started cups-browsed.service - Make remote CUPS printers available locally.          Starting exim4.service - exim Mail Transport Agent...          Starting xrdp.service - xrdp daemon... [  OK  ] Finished user-runtime-dir@1000.service - User Runtime Directory /run/user/1000. [  OK  ] Started xrdp.service - xrdp daemon. [  OK  ] Started serial-getty@ttyHV0.service - Serial Getty on ttyHV0.          Starting user@1000.service - User Manager for UID 1000... [  OK  ] Started exim4.service - exim Mail Transport Agent. [  OK  ] Reached target multi-user.target - Multi-User System. [  OK  ] Reached target graphical.target - Graphical Interface. [  OK  ] Started user@1000.service - User Manager for UID 1000. [FAILED] Failed to start session-1.scope - Session 1 of User tonyr. See 'systemctl status session-1.scope' for details. [  206.412865] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [  206.424477] rcu:     114-...!: (430 GPs behind) idle=97b0/0/0x0 softirq=126/126 fqs=0 (false positive?) [  206.442691] rcu:     (detected by 123, t=5259 jiffies, g=3793, q=5473 ncpus=256) [  206.457056] rcu: rcu_sched kthread timer wakeup didn't happen for 5261 jiffies! g3793 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 [  206.479157] rcu:     Possible timer handling issue on cpu=2 timer-softirq=330 [  206.492868] rcu: rcu_sched kthread starved for 5271 jiffies! g3793 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2 [  206.513173] rcu:     Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior. [  206.531061] rcu: RCU grace-period kthread stack dump: [  206.541202] rcu: Stack dump where RCU GP kthread last ran: NOTE(S): Unable to login and random hangs during system startup. Same messages/issues as S7-2. > > On 5/8/26 12:50 AM, Thorsten Leemhuis wrote: >> [+tglx so he knows about it; details about the problem that Tony faces >> can be found in https://github.com/sparclinux/issues/issues/79 ] >> >> On 5/8/26 09:38, Tony Rodriguez wrote: >>> I still don't believe this is fixed upstream as of v7.03 and v7.1-rc1, >> Yes and no. It looks like d6e152d905bdb1 ("clockevents: Prevent timer >> interrupt starvation") causes two regression. >> >> Thomas fixed one with 4096fd0e8eaea1 ("clockevents: Add missing resets >> of the next_event_forced flag") -- and feedback shows that it definitely >> solved the problem for quite a few people. If that's not the case for >> you, then you seem to face a different problem caused by the same >> change. Happens, that's life sometimes. >> >> Ciao, Thorsten >> >>> only when my patch is applied does the SPARC64 S7-2 system become >>> stable >>> again. I also tested my patch with v7.0.4 and it works their as well. >>> Will perform additional tests without my fix against v7.0.4 and >>> v7.1-rc2 >>> later today to revalidate the regression (USA Pacific time). >>> >>> Tony Rodriguez >>> www.linkedin.com/in/unixpro1970 >>> >>>> On May 7, 2026, at 11:33 PM, Thorsten Leemhuis >>>> wrote: >>>> >>>> On 5/8/26 07:51, John Paul Adrian Glaubitz wrote: >>>>> On Thu, 2026-04-23 at 18:30 +0200, Thorsten Leemhuis wrote: >>>>>> FWIW, here is the rough timeline of the regression, just to be >>>>>> sure we >>>>>> are all on the same page: >>>>>> >>>>>> * The regression I'm talking about is caused by d6e152d905bdb1 >>>>>> ("clockevents: Prevent timer interrupt starvation") [authored: >>>>>> 2026-04-07 10:54:17; committed: 2026-04-10 22:45:38; next arrival: >>>>>> next-20260413; merged: 2026-04-12 19:01:55; v7.0 (2026-04-12 >>>>>> 22:48:06)] >>>>> [...] >>>>> Tony Rodriguez from the SPARC community has observed the regression >>>>> on SPARC as well >>>>> and proposed a fix to address it [1]. Not sure whether he has >>>>> retested on the latest >>>>> commit of Linus' tree yet. >>>>> >>>>> Tony, can you verify that 4096fd0e8eaea1 fixes the issue for you? >>>>> >>>>>> [1] https://github.com/sparclinux/issues/issues/79 >>>> It's likely a different regressions, as that report's title says that >>>> v7.0.1, v7.0.2, v7.0.3, and v7.1‑rc1 are affected, which all >>>> contain the >>>> fix, aka 4096fd0e8eaea1. Reporting in a new thread is likely best, as >>>> the authors of the culprit are not even CCed here. >>>> >>>> Ciao, Thorsten