* [linux-next:master] [lib/Kconfig.debug] 888c290a02: BUG:MAX_LOCKDEP_CHAINS_too_low
@ 2026-05-31 8:52 kernel test robot
2026-05-31 10:09 ` Tetsuo Handa
0 siblings, 1 reply; 3+ messages in thread
From: kernel test robot @ 2026-05-31 8:52 UTC (permalink / raw)
To: Tetsuo Handa; +Cc: oe-lkp, lkp, linux-kernel, oliver.sang
Hello,
this report is just FYI.
as we understand, this is a debug patch. and by it, we notice below config diff:
--- /pkg/linux/x86_64-randconfig-161-20260529/gcc-14/e66d61ddb1d8504e4bfd3dcc3fa26293f9d14d9d/.config 2026-05-30 00:10:22.784053022 +0800
+++ /pkg/linux/x86_64-randconfig-161-20260529/gcc-14/888c290a0240da1ce1a4d69beafe44f9abec93c0/.config 2026-05-29 23:38:02.317371800 +0800
@@ -97,6 +97,7 @@ CONFIG_HRTIMER_REARM_DEFERRED=y
CONFIG_HAVE_POSIX_CPU_TIMERS_TASK_WORK=y
CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y
CONFIG_CONTEXT_TRACKING=y
+CONFIG_CONTEXT_TRACKING_IDLE=y
#
# Timers subsystem
@@ -129,7 +130,8 @@ CONFIG_PREEMPT_BUILD=y
CONFIG_ARCH_HAS_PREEMPT_LAZY=y
# CONFIG_PREEMPT is not set
CONFIG_PREEMPT_LAZY=y
-# CONFIG_PREEMPT_RT is not set
+CONFIG_PREEMPT_RT=y
+CONFIG_PREEMPT_RT_NEEDS_BH_LOCK=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y
# CONFIG_PREEMPT_DYNAMIC is not set
@@ -150,9 +152,11 @@ CONFIG_PSI=y
#
# RCU Subsystem
#
-CONFIG_TINY_RCU=y
+CONFIG_TREE_RCU=y
+CONFIG_PREEMPT_RCU=y
CONFIG_RCU_EXPERT=y
-CONFIG_TINY_SRCU=y
+CONFIG_TREE_SRCU=y
+# CONFIG_FORCE_NEED_SRCU_NMI_SAFE is not set
CONFIG_TASKS_RCU_GENERIC=y
CONFIG_FORCE_TASKS_RCU=y
CONFIG_NEED_TASKS_RCU=y
@@ -162,7 +166,18 @@ CONFIG_TASKS_RUDE_RCU=y
CONFIG_FORCE_TASKS_TRACE_RCU=y
CONFIG_TASKS_TRACE_RCU=y
CONFIG_TASKS_TRACE_RCU_NO_MB=y
+CONFIG_RCU_STALL_COMMON=y
CONFIG_RCU_NEED_SEGCBLIST=y
+CONFIG_RCU_FANOUT=64
+CONFIG_RCU_FANOUT_LEAF=2
+CONFIG_RCU_BOOST=y
+CONFIG_RCU_BOOST_DELAY=500
+CONFIG_RCU_EXP_KTHREAD=y
+CONFIG_RCU_NOCB_CPU=y
+# CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set
+# CONFIG_RCU_NOCB_CPU_CB_BOOST is not set
+CONFIG_RCU_LAZY=y
+# CONFIG_RCU_LAZY_DEFAULT_OFF is not set
# CONFIG_RCU_DOUBLE_CHECK_CB_TIME is not set
# end of RCU Subsystem
@@ -176,7 +191,6 @@ CONFIG_HAVE_UNSTABLE_SCHED_CLOCK=y
#
# Scheduler features
#
-# CONFIG_SCHED_PROXY_EXEC is not set
# end of Scheduler features
CONFIG_ARCH_SUPPORTS_NUMA_BALANCING=y
@@ -772,7 +786,6 @@ CONFIG_MODULES_USE_ELF_RELA=y
CONFIG_ARCH_HAS_EXECMEM_ROX=y
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK=y
CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK=y
-CONFIG_SOFTIRQ_ON_OWN_STACK=y
CONFIG_ARCH_HAS_ELF_RANDOMIZE=y
CONFIG_HAVE_ARCH_MMAP_RND_BITS=y
CONFIG_HAVE_EXIT_THREAD=y
@@ -974,7 +987,6 @@ CONFIG_MMU_NOTIFIER=y
CONFIG_DEFAULT_MMAP_MIN_ADDR=4096
CONFIG_ARCH_WANT_GENERAL_HUGETLB=y
CONFIG_ARCH_WANTS_THP_SWAP=y
-# CONFIG_TRANSPARENT_HUGEPAGE is not set
CONFIG_PAGE_MAPCOUNT=y
CONFIG_PGTABLE_HAS_HUGE_LEAVES=y
CONFIG_HAVE_GIGANTIC_FOLIOS=y
@@ -4202,9 +4214,9 @@ CONFIG_DRM_ETNAVIV_THERMAL=y
# CONFIG_DRM_GMA500 is not set
CONFIG_DRM_GUD=y
CONFIG_DRM_HISI_HIBMC=y
-# CONFIG_DRM_I915 is not set
# CONFIG_DRM_LOGICVC is not set
CONFIG_DRM_MGAG200=y
+CONFIG_DRM_MGAG200_DISABLE_WRITECOMBINE=y
CONFIG_DRM_NOUVEAU=y
CONFIG_NOUVEAU_DEBUG=5
CONFIG_NOUVEAU_DEBUG_DEFAULT=3
@@ -4895,7 +4907,6 @@ CONFIG_LEDS_TRIGGER_DISK=y
CONFIG_LEDS_TRIGGER_MTD=y
CONFIG_LEDS_TRIGGER_HEARTBEAT=y
CONFIG_LEDS_TRIGGER_BACKLIGHT=y
-# CONFIG_LEDS_TRIGGER_CPU is not set
CONFIG_LEDS_TRIGGER_ACTIVITY=y
CONFIG_LEDS_TRIGGER_GPIO=y
CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
@@ -7388,7 +7399,6 @@ CONFIG_HARDLOCKUP_CHECK_TIMESTAMP=y
CONFIG_DETECT_HUNG_TASK=y
CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=480
CONFIG_BOOTPARAM_HUNG_TASK_PANIC=0
-CONFIG_DETECT_HUNG_TASK_BLOCKER=y
CONFIG_WQ_WATCHDOG=y
CONFIG_BOOTPARAM_WQ_STALL_PANIC=0
# CONFIG_WQ_CPU_INTENSIVE_REPORT is not set
@@ -7415,9 +7425,7 @@ CONFIG_PROVE_RAW_LOCK_NESTING=y
# CONFIG_LOCK_STAT is not set
CONFIG_DEBUG_RT_MUTEXES=y
CONFIG_DEBUG_SPINLOCK=y
-CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y
-CONFIG_DEBUG_RWSEMS=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_LOCKDEP=y
CONFIG_LOCKDEP_BITS=15
@@ -7463,8 +7471,13 @@ CONFIG_RCU_TORTURE_TEST_CHK_RDR_STATE=y
# CONFIG_RCU_TORTURE_TEST_LOG_CPU is not set
CONFIG_RCU_TORTURE_TEST_LOG_GP=y
CONFIG_RCU_REF_SCALE_TEST=m
+CONFIG_RCU_CPU_STALL_TIMEOUT=21
+CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=0
+CONFIG_RCU_CPU_STALL_CPUTIME=y
+CONFIG_RCU_CPU_STALL_NOTIFIER=y
CONFIG_RCU_TRACE=y
CONFIG_RCU_EQS_DEBUG=y
+CONFIG_RCU_STRICT_GRACE_PERIOD=y
# CONFIG_RCU_DYNTICKS_TORTURE is not set
# CONFIG_TRIVIAL_PREEMPT_RCU is not set
# end of RCU Debugging
then we notice issues as below full report.
just FYI what we observed in our tests.
kernel test robot noticed "BUG:MAX_LOCKDEP_CHAINS_too_low" on:
commit: 888c290a0240da1ce1a4d69beafe44f9abec93c0 ("lib/Kconfig.debug: enable CONFIG_PREEMPT_RT for syzbot kernels.")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
[test failed on linux-next/master f7af91adc230aa99e23330ecf85bc9badd9780ad]
in testcase: trinity
version: trinity-i386-abe9de86-1_20230429
with following parameters:
runtime: 300s
group: group-04
nr_groups: 5
config: x86_64-randconfig-161-20260529
compiler: gcc-14
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202605311625.72d32001-lkp@intel.com
[ 467.321357][ T4078] BUG: MAX_LOCKDEP_CHAINS too low!
[ 467.321374][ T4078] turning off the locking correctness validator.
[ 467.321400][ T4078] CPU: 0 UID: 65534 PID: 4078 Comm: trinity-main Tainted: G T 7.1.0-rc5-00005-g888c290a0240 #1 PREEMPT_{RT,LAZY}
[ 467.321419][ T4078] Tainted: [T]=RANDSTRUCT
[ 467.321431][ T4078] Call Trace:
[ 467.321436][ T4078] <TASK>
[ 467.321443][ T4078] dump_stack_lvl (dump_stack.c:94 dump_stack.c:120)
[ 467.321482][ T4078] dump_stack (dump_stack.c:129)
[ 467.321492][ T4078] add_chain_cache (locking/lockdep.c:3755)
[ 467.321512][ T4078] validate_chain (locking/lockdep.c:3857 locking/lockdep.c:3878)
[ 467.321526][ T4078] __lock_acquire (locking/lockdep.c:5239)
[ 467.321539][ T4078] ? lock_hrtimer_base+0x32/0x80
[ 467.321552][ T4078] lock_acquire (locking/lockdep.c:5870)
[ 467.321561][ T4078] ? lock_hrtimer_base+0x32/0x80
[ 467.321574][ T4078] ? __lock_acquire (locking/lockdep.c:5239)
[ 467.321588][ T4078] _raw_spin_lock_irqsave (linux/spinlock_api_smp.h:132 (discriminator 1) locking/spinlock.c:166 (discriminator 1))
[ 467.321609][ T4078] ? lock_hrtimer_base+0x32/0x80
[ 467.321621][ T4078] lock_hrtimer_base+0x32/0x80
[ 467.321633][ T4078] hrtimer_start_range_ns (time/hrtimer.c:1489)
[ 467.321645][ T4078] ? __hrtimer_start_range_ns (time/hrtimer.c:1460)
[ 467.321658][ T4078] ? kvm_clock_read (x86/kernel/kvmclock.c:80 (discriminator 1))
[ 467.321672][ T4078] hrtick_cond_restart (linux/hrtimer.h:220 sched/core.c:924)
[ 467.321684][ T4078] hrtick_schedule_exit+0x2c/0x80
[ 467.321695][ T4078] finish_task_switch+0x38f/0x540
[ 467.321708][ T4078] ? finish_task_switch+0x376/0x540
[ 467.321723][ T4078] __schedule (sched/core.c:5391 sched/core.c:7189)
[ 467.321738][ T4078] ? io_schedule_timeout (sched/core.c:8102)
[ 467.321753][ T4078] ? might_alloc (linux/sched/mm.h:317)
[ 467.321766][ T4078] preempt_schedule_notrace (sched/core.c:7463)
[ 467.321779][ T4078] preempt_schedule_notrace_thunk (x86/entry/thunk.S:13)
[ 467.321795][ T4078] rcu_is_watching (rcu/tree.c:753 (discriminator 1))
[ 467.321807][ T4078] lock_acquire (trace/events/lock.h:24 (discriminator 11) locking/lockdep.c:5833 (discriminator 11))
[ 467.321817][ T4078] ? kernfs_fop_open (kernfs/file.c:619)
[ 467.321828][ T4078] ? lock_acquire (locking/lockdep.c:5870)
[ 467.321837][ T4078] ? kernfs_fop_open (linux/slab.h:950 linux/slab.h:1188 kernfs/file.c:641)
[ 467.321846][ T4078] __fs_reclaim_acquire (page_alloc.c:4325)
[ 467.321857][ T4078] ? might_alloc (linux/sched/mm.h:317)
[ 467.321867][ T4078] fs_reclaim_acquire (page_alloc.c:4339 (discriminator 1))
[ 467.321877][ T4078] might_alloc (linux/sched/mm.h:317)
[ 467.321887][ T4078] __kmalloc_cache_noprof (slub.c:4521 slub.c:4876 slub.c:5415)
[ 467.321902][ T4078] kernfs_fop_open (linux/slab.h:950 linux/slab.h:1188 kernfs/file.c:641)
[ 467.321916][ T4078] ? kernfs_fop_release (kernfs/file.c:789)
[ 467.321924][ T4078] do_dentry_open (open.c:947)
[ 467.321941][ T4078] vfs_open (open.c:1079)
[ 467.321952][ T4078] do_open (namei.c:4699)
[ 467.321969][ T4078] path_openat (namei.c:4858)
[ 467.321980][ T4078] ? kernel_tmpfile_open (namei.c:4800)
[ 467.321992][ T4078] ? rt_mutex_slowunlock (locking/rtmutex.c:350 locking/rtmutex.c:1463)
[ 467.322007][ T4078] do_file_open (namei.c:4887)
[ 467.322018][ T4078] ? path_openat (namei.c:4875)
[ 467.322032][ T4078] ? mark_wakeup_next_waiter (locking/rtmutex.c:1364)
[ 467.322063][ T4078] do_sys_openat2 (open.c:1364 (discriminator 1))
[ 467.322075][ T4078] ? file_open_root (open.c:1352)
[ 467.322090][ T4078] ? __lock_acquire (locking/lockdep.c:5239)
[ 467.322102][ T4078] do_sys_open (open.c:1370)
[ 467.322113][ T4078] ? filp_open (open.c:1340)
[ 467.322124][ T4078] ? vtime_user_exit (sched/cputime.c:743 (discriminator 1))
[ 467.322136][ T4078] ? __lock_release+0x4e/0x140
[ 467.322149][ T4078] __ia32_compat_sys_openat (open.c:1432 open.c:1430 open.c:1430)
[ 467.322162][ T4078] ia32_sys_call (kbuild/obj/consumer/x86_64-randconfig-161-20260529/./arch/x86/include/generated/asm/syscalls_32.h:296)
[ 467.322174][ T4078] __do_fast_syscall_32 (x86/entry/syscall_32.c:83 x86/entry/syscall_32.c:307)
[ 467.322186][ T4078] ? preempt_latency_start (linux/ftrace.h:1168 sched/core.c:5837)
[ 467.322198][ T4078] ? __do_fast_syscall_32 (linux/randomize_kstack.h:58 x86/entry/syscall_32.c:279)
[ 467.322210][ T4078] do_fast_syscall_32 (x86/entry/syscall_32.c:332)
[ 467.322220][ T4078] do_SYSENTER_32 (x86/entry/syscall_32.c:370)
[ 467.322229][ T4078] entry_SYSENTER_compat_after_hwframe (x86/entry/entry_64_compat.S:126)
[ 467.322241][ T4078] RIP: 0023:0xf7fb938c
[ 467.322252][ T4078] Code: d2 74 05 c1 e8 0c 89 02 8b 5d fc 31 c0 c9 31 d2 31 c9 c3 cc 90 90 90 90 90 90 90 90 90 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
All code
========
0: d2 74 05 c1 shlb %cl,-0x3f(%rbp,%rax,1)
4: e8 0c 89 02 8b call 0xffffffff8b028915
9: 5d pop %rbp
a: fc cld
b: 31 c0 xor %eax,%eax
d: c9 leave
e: 31 d2 xor %edx,%edx
10: 31 c9 xor %ecx,%ecx
12: c3 ret
13: cc int3
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: 90 nop
1c: 90 nop
1d: 90 nop
1e: 0f 1f 00 nopl (%rax)
21: 51 push %rcx
22: 52 push %rdx
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
2a:* 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 ret
2e: cc int3
2f: 90 nop
30: 90 nop
31: 90 nop
32: 90 nop
33: 90 nop
34: 90 nop
35: 90 nop
36: 90 nop
37: 90 nop
38: 90 nop
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop
Code starting with the faulting instruction
===========================================
0: 5d pop %rbp
1: 5a pop %rdx
2: 59 pop %rcx
3: c3 ret
4: cc int3
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260531/202605311625.72d32001-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [linux-next:master] [lib/Kconfig.debug] 888c290a02: BUG:MAX_LOCKDEP_CHAINS_too_low
2026-05-31 8:52 [linux-next:master] [lib/Kconfig.debug] 888c290a02: BUG:MAX_LOCKDEP_CHAINS_too_low kernel test robot
@ 2026-05-31 10:09 ` Tetsuo Handa
2026-06-01 2:47 ` Oliver Sang
0 siblings, 1 reply; 3+ messages in thread
From: Tetsuo Handa @ 2026-05-31 10:09 UTC (permalink / raw)
To: kernel test robot; +Cc: oe-lkp, lkp, linux-kernel
Hello.
The "lib/Kconfig.debug: enable CONFIG_PREEMPT_RT for syzbot kernels." patch was working
for a while without problems. I think you can test with "CONFIG_DEBUG_AID_FOR_SYZBOT=n"
to avoid this problem. Can you tell me what your problem is?
On 2026/05/31 17:52, kernel test robot wrote:
>
>
> Hello,
>
>
> this report is just FYI.
>
> as we understand, this is a debug patch. and by it, we notice below config diff:
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [linux-next:master] [lib/Kconfig.debug] 888c290a02: BUG:MAX_LOCKDEP_CHAINS_too_low
2026-05-31 10:09 ` Tetsuo Handa
@ 2026-06-01 2:47 ` Oliver Sang
0 siblings, 0 replies; 3+ messages in thread
From: Oliver Sang @ 2026-06-01 2:47 UTC (permalink / raw)
To: Tetsuo Handa; +Cc: oe-lkp, lkp, linux-kernel, oliver.sang
hi, Tetsuo Handa,
On Sun, May 31, 2026 at 07:09:28PM +0900, Tetsuo Handa wrote:
> Hello.
>
> The "lib/Kconfig.debug: enable CONFIG_PREEMPT_RT for syzbot kernels." patch was working
> for a while without problems. I think you can test with "CONFIG_DEBUG_AID_FOR_SYZBOT=n"
thanks for information!
> to avoid this problem. Can you tell me what your problem is?
we don't have problem. this is just a bot to test/bisect linux kernels. as you
can see in our oiginal report, this is a trinity test with randconfig. and with
888c290a02, there are some expected config diff then we just report what the
issues we saw in this trinity tests.
ok, we won't report this commit any longer. thanks
>
> On 2026/05/31 17:52, kernel test robot wrote:
> >
> >
> > Hello,
> >
> >
> > this report is just FYI.
> >
> > as we understand, this is a debug patch. and by it, we notice below config diff:
> >
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-06-01 2:47 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2026-05-31 8:52 [linux-next:master] [lib/Kconfig.debug] 888c290a02: BUG:MAX_LOCKDEP_CHAINS_too_low kernel test robot
2026-05-31 10:09 ` Tetsuo Handa
2026-06-01 2:47 ` Oliver Sang
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