INFO: rcu detected stall in kthread_worker_fn (2)

INFO: rcu detected stall in kthread_worker_fn (2)

Status: upstream: reported syz repro on 2025/03/13 09:29
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+2ea3f3959d6a151d0865@syzkaller.appspotmail.com
First crash: 466d, last: 16d

Cause bisection: introduced by (bisect log) :
commit 5a781ccbd19e4664babcbe4b4ead7aa2b9283d22
Author: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Date: Sat Sep 29 00:59:43 2018 +0000

tc: Add support for configuring the taprio scheduler

Crash: no output from test machine (log)
Repro: syz .config

Fix bisection: failed (error log, bisect log)

▶ ▼ ✨ AI Jobs (4)

ID	Workflow	Result	Correct	Ext Bug ID	Bug	Created	Started	Finished	Revision	Error
7ff4d3bd-f3b9-4a34-b261-9672e4fbd7c8	assessment-security		💥		INFO: rcu detected stall in kthread_worker_fn (2)	2026/06/10 01:43	2026/06/10 01:43	2026/06/10 02:10	c36c07f6c1f2230a36374cbd22235f635e8f9284	failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/32bc55683a962153b592958552894278a8a98ff8" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General setup * Compile also drivers which will not load (COMPILE_TEST) [N/y/?] n Compile the kernel with warnings as errors (WERROR) [N/y/?] n Local version - append to kernel release (LOCALVERSION) [] Automatically append version information to the version string (LOCALVERSION_AUTO) [Y/n/?] y Build ID Salt (BUILD_SALT) [] Kernel compression mode > 1. Gzip (KERNEL_GZIP) 2. Bzip2 (KERNEL_BZIP2) 3. LZMA (KERNEL_LZMA) 4. XZ (KERNEL_XZ) 5. LZO (KERNEL_LZO) 6. LZ4 (KERNEL_LZ4) 7. ZSTD (KERNEL_ZSTD) choice[1-7?]: 1 Default init path (DEFAULT_INIT) [] Default hostname (DEFAULT_HOSTNAME) [(none)] (none) System V IPC (SYSVIPC) [Y/n/?] y POSIX Message Queues (POSIX_MQUEUE) [Y/n/?] y General notification queue (WATCH_QUEUE) [Y/n/?] y Enable process_vm_readv/writev syscalls (CROSS_MEMORY_ATTACH) [Y/n/?] y uselib syscall (for libc5 and earlier) (USELIB) [N/y/?] n Auditing support (AUDIT) [Y/?] y Preemption Model 1. No Forced Preemption (Server) (PREEMPT_NONE) 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) 4. Scheduler controlled preemption model (PREEMPT_LAZY) choice[1-4?]: 3 Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) [N/y/?] n Preemption behaviour defined on boot (PREEMPT_DYNAMIC) [Y/n/?] y Core Scheduling for SMT (SCHED_CORE) [Y/n/?] y CPU isolation (CPU_ISOLATION) [Y/n/?] y Kernel .config support (IKCONFIG) [Y/n/m/?] y Enable access to .config through /proc/config.gz (IKCONFIG_PROC) [Y/n/?] y Enable kernel headers through /sys/kernel/kheaders.tar.xz (IKHEADERS) [N/m/y/?] n Kernel log buffer size (16 => 64KB, 17 => 128KB) (LOG_BUF_SHIFT) [18] 18 CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB) (LOG_CPU_MAX_BUF_SHIFT) [12] 12 Printk indexing debugfs interface (PRINTK_INDEX) [N/y/?] n Memory placement aware NUMA scheduler (NUMA_BALANCING) [Y/n/?] y Automatically enable NUMA aware memory/task placement (NUMA_BALANCING_DEFAULT_ENABLED) [Y/n/?] y Checkpoint/restore support (CHECKPOINT_RESTORE) [Y/n/?] y Automatic process group scheduling (SCHED_AUTOGROUP) [N/y/?] n Kernel->user space relay support (formerly relayfs) (RELAY) [Y/?] y Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD) [Y/n/?] y Initramfs source file(s) (INITRAMFS_SOURCE) [] Support initial ramdisk/ramfs compressed using gzip (RD_GZIP) [Y/n/?] y Support initial ramdisk/ramfs compressed using bzip2 (RD_BZIP2) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZMA (RD_LZMA) [Y/n/?] y Support initial ramdisk/ramfs compressed using XZ (RD_XZ) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZO (RD_LZO) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZ4 (RD_LZ4) [Y/n/?] y Support initial ramdisk/ramfs compressed using ZSTD (RD_ZSTD) [Y/n/?] y Boot config support (BOOT_CONFIG) [N/y/?] n Preserve cpio archive mtimes in initramfs (INITRAMFS_PRESERVE_MTIME) [Y/n/?] y Compiler optimization level > 1. Optimize for performance (-O2) (CC_OPTIMIZE_FOR_PERFORMANCE) 2. Optimize for size (-Os) (CC_OPTIMIZE_FOR_SIZE) choice[1-2?]: 1 Enable madvise/fadvise syscalls (ADVISE_SYSCALLS) [Y/n/?] y Enable membarrier() system call (MEMBARRIER) [Y/?] y Enable kcmp() system call (KCMP) [Y/?] y Enable rseq() system call (RSEQ) [Y/n/?] y Enable debugging of rseq() system call (DEBUG_RSEQ) [N/y/?] n Enable cachestat() system call (CACHESTAT_SYSCALL) [Y/n/?] y PC/104 support (PC104) [N/y/?] n Load all symbols for debugging/ksymoops (KALLSYMS) [Y/?] y Test the basic functions and performance of kallsyms (KALLSYMS_SELFTEST) [N/y/?] n Include all symbols in kallsyms (KALLSYMS_ALL) [Y/?] y Profiling support (PROFILING) [Y/n/?] y Rust support (RUST) [N/y/?] (NE
26dd9823-a91b-4787-a543-45ff0caae34e	assessment-security		💥		INFO: rcu detected stall in kthread_worker_fn (2)	2026/06/04 04:15	2026/06/04 04:15	2026/06/04 04:35	62fe15281f5011cd203d8845b8767b10e7443aa5	failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/32bc55683a962153b592958552894278a8a98ff8" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General setup * Compile also drivers which will not load (COMPILE_TEST) [N/y/?] n Compile the kernel with warnings as errors (WERROR) [N/y/?] n Local version - append to kernel release (LOCALVERSION) [] Automatically append version information to the version string (LOCALVERSION_AUTO) [Y/n/?] y Build ID Salt (BUILD_SALT) [] Kernel compression mode > 1. Gzip (KERNEL_GZIP) 2. Bzip2 (KERNEL_BZIP2) 3. LZMA (KERNEL_LZMA) 4. XZ (KERNEL_XZ) 5. LZO (KERNEL_LZO) 6. LZ4 (KERNEL_LZ4) 7. ZSTD (KERNEL_ZSTD) choice[1-7?]: 1 Default init path (DEFAULT_INIT) [] Default hostname (DEFAULT_HOSTNAME) [(none)] (none) System V IPC (SYSVIPC) [Y/n/?] y POSIX Message Queues (POSIX_MQUEUE) [Y/n/?] y General notification queue (WATCH_QUEUE) [Y/n/?] y Enable process_vm_readv/writev syscalls (CROSS_MEMORY_ATTACH) [Y/n/?] y uselib syscall (for libc5 and earlier) (USELIB) [N/y/?] n Auditing support (AUDIT) [Y/?] y Preemption Model 1. No Forced Preemption (Server) (PREEMPT_NONE) 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) 4. Scheduler controlled preemption model (PREEMPT_LAZY) choice[1-4?]: 3 Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) [N/y/?] n Preemption behaviour defined on boot (PREEMPT_DYNAMIC) [Y/n/?] y Core Scheduling for SMT (SCHED_CORE) [Y/n/?] y CPU isolation (CPU_ISOLATION) [Y/n/?] y Kernel .config support (IKCONFIG) [Y/n/m/?] y Enable access to .config through /proc/config.gz (IKCONFIG_PROC) [Y/n/?] y Enable kernel headers through /sys/kernel/kheaders.tar.xz (IKHEADERS) [N/m/y/?] n Kernel log buffer size (16 => 64KB, 17 => 128KB) (LOG_BUF_SHIFT) [18] 18 CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB) (LOG_CPU_MAX_BUF_SHIFT) [12] 12 Printk indexing debugfs interface (PRINTK_INDEX) [N/y/?] n Memory placement aware NUMA scheduler (NUMA_BALANCING) [Y/n/?] y Automatically enable NUMA aware memory/task placement (NUMA_BALANCING_DEFAULT_ENABLED) [Y/n/?] y Checkpoint/restore support (CHECKPOINT_RESTORE) [Y/n/?] y Automatic process group scheduling (SCHED_AUTOGROUP) [N/y/?] n Kernel->user space relay support (formerly relayfs) (RELAY) [Y/?] y Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD) [Y/n/?] y Initramfs source file(s) (INITRAMFS_SOURCE) [] Support initial ramdisk/ramfs compressed using gzip (RD_GZIP) [Y/n/?] y Support initial ramdisk/ramfs compressed using bzip2 (RD_BZIP2) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZMA (RD_LZMA) [Y/n/?] y Support initial ramdisk/ramfs compressed using XZ (RD_XZ) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZO (RD_LZO) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZ4 (RD_LZ4) [Y/n/?] y Support initial ramdisk/ramfs compressed using ZSTD (RD_ZSTD) [Y/n/?] y Boot config support (BOOT_CONFIG) [N/y/?] n Preserve cpio archive mtimes in initramfs (INITRAMFS_PRESERVE_MTIME) [Y/n/?] y Compiler optimization level > 1. Optimize for performance (-O2) (CC_OPTIMIZE_FOR_PERFORMANCE) 2. Optimize for size (-Os) (CC_OPTIMIZE_FOR_SIZE) choice[1-2?]: 1 Enable madvise/fadvise syscalls (ADVISE_SYSCALLS) [Y/n/?] y Enable membarrier() system call (MEMBARRIER) [Y/?] y Enable kcmp() system call (KCMP) [Y/?] y Enable rseq() system call (RSEQ) [Y/n/?] y Enable debugging of rseq() system call (DEBUG_RSEQ) [N/y/?] n Enable cachestat() system call (CACHESTAT_SYSCALL) [Y/n/?] y PC/104 support (PC104) [N/y/?] n Load all symbols for debugging/ksymoops (KALLSYMS) [Y/?] y Test the basic functions and performance of kallsyms (KALLSYMS_SELFTEST) [N/y/?] n Include all symbols in kallsyms (KALLSYMS_ALL) [Y/?] y Profiling support (PROFILING) [Y/n/?] y Rust support (RUST) [N/y/?] (NE
d550d69a-6f1d-45eb-9d68-5762551d0de1	assessment-security		💥		INFO: rcu detected stall in kthread_worker_fn (2)	2026/06/01 21:20	2026/06/01 21:20	2026/06/01 21:53	386cc6dacdf7e3ebce9507beed6755d7e999554d	failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/32bc55683a962153b592958552894278a8a98ff8" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General setup * Compile also drivers which will not load (COMPILE_TEST) [N/y/?] n Compile the kernel with warnings as errors (WERROR) [N/y/?] n Local version - append to kernel release (LOCALVERSION) [] Automatically append version information to the version string (LOCALVERSION_AUTO) [Y/n/?] y Build ID Salt (BUILD_SALT) [] Kernel compression mode > 1. Gzip (KERNEL_GZIP) 2. Bzip2 (KERNEL_BZIP2) 3. LZMA (KERNEL_LZMA) 4. XZ (KERNEL_XZ) 5. LZO (KERNEL_LZO) 6. LZ4 (KERNEL_LZ4) 7. ZSTD (KERNEL_ZSTD) choice[1-7?]: 1 Default init path (DEFAULT_INIT) [] Default hostname (DEFAULT_HOSTNAME) [(none)] (none) System V IPC (SYSVIPC) [Y/n/?] y POSIX Message Queues (POSIX_MQUEUE) [Y/n/?] y General notification queue (WATCH_QUEUE) [Y/n/?] y Enable process_vm_readv/writev syscalls (CROSS_MEMORY_ATTACH) [Y/n/?] y uselib syscall (for libc5 and earlier) (USELIB) [N/y/?] n Auditing support (AUDIT) [Y/?] y Preemption Model 1. No Forced Preemption (Server) (PREEMPT_NONE) 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) 4. Scheduler controlled preemption model (PREEMPT_LAZY) choice[1-4?]: 3 Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) [N/y/?] n Preemption behaviour defined on boot (PREEMPT_DYNAMIC) [Y/n/?] y Core Scheduling for SMT (SCHED_CORE) [Y/n/?] y CPU isolation (CPU_ISOLATION) [Y/n/?] y Kernel .config support (IKCONFIG) [Y/n/m/?] y Enable access to .config through /proc/config.gz (IKCONFIG_PROC) [Y/n/?] y Enable kernel headers through /sys/kernel/kheaders.tar.xz (IKHEADERS) [N/m/y/?] n Kernel log buffer size (16 => 64KB, 17 => 128KB) (LOG_BUF_SHIFT) [18] 18 CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB) (LOG_CPU_MAX_BUF_SHIFT) [12] 12 Printk indexing debugfs interface (PRINTK_INDEX) [N/y/?] n Memory placement aware NUMA scheduler (NUMA_BALANCING) [Y/n/?] y Automatically enable NUMA aware memory/task placement (NUMA_BALANCING_DEFAULT_ENABLED) [Y/n/?] y Checkpoint/restore support (CHECKPOINT_RESTORE) [Y/n/?] y Automatic process group scheduling (SCHED_AUTOGROUP) [N/y/?] n Kernel->user space relay support (formerly relayfs) (RELAY) [Y/?] y Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD) [Y/n/?] y Initramfs source file(s) (INITRAMFS_SOURCE) [] Support initial ramdisk/ramfs compressed using gzip (RD_GZIP) [Y/n/?] y Support initial ramdisk/ramfs compressed using bzip2 (RD_BZIP2) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZMA (RD_LZMA) [Y/n/?] y Support initial ramdisk/ramfs compressed using XZ (RD_XZ) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZO (RD_LZO) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZ4 (RD_LZ4) [Y/n/?] y Support initial ramdisk/ramfs compressed using ZSTD (RD_ZSTD) [Y/n/?] y Boot config support (BOOT_CONFIG) [N/y/?] n Preserve cpio archive mtimes in initramfs (INITRAMFS_PRESERVE_MTIME) [Y/n/?] y Compiler optimization level > 1. Optimize for performance (-O2) (CC_OPTIMIZE_FOR_PERFORMANCE) 2. Optimize for size (-Os) (CC_OPTIMIZE_FOR_SIZE) choice[1-2?]: 1 Enable madvise/fadvise syscalls (ADVISE_SYSCALLS) [Y/n/?] y Enable membarrier() system call (MEMBARRIER) [Y/?] y Enable kcmp() system call (KCMP) [Y/?] y Enable rseq() system call (RSEQ) [Y/n/?] y Enable debugging of rseq() system call (DEBUG_RSEQ) [N/y/?] n Enable cachestat() system call (CACHESTAT_SYSCALL) [Y/n/?] y PC/104 support (PC104) [N/y/?] n Load all symbols for debugging/ksymoops (KALLSYMS) [Y/?] y Test the basic functions and performance of kallsyms (KALLSYMS_SELFTEST) [N/y/?] n Include all symbols in kallsyms (KALLSYMS_ALL) [Y/?] y Profiling support (PROFILING) [Y/n/?] y Rust support (RUST) [N/y/?] (NE
5af426de-8a0d-4b5c-9e14-137fd402d3d6	assessment-security		💥		INFO: rcu detected stall in kthread_worker_fn (2)	2026/05/18 08:13	2026/05/18 08:13	2026/05/18 08:42	de5aae85e5f28e2fa1c7deefcc24fe286abe5140	failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/32bc55683a962153b592958552894278a8a98ff8" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General setup * Compile also drivers which will not load (COMPILE_TEST) [N/y/?] n Compile the kernel with warnings as errors (WERROR) [N/y/?] n Local version - append to kernel release (LOCALVERSION) [] Automatically append version information to the version string (LOCALVERSION_AUTO) [Y/n/?] y Build ID Salt (BUILD_SALT) [] Kernel compression mode > 1. Gzip (KERNEL_GZIP) 2. Bzip2 (KERNEL_BZIP2) 3. LZMA (KERNEL_LZMA) 4. XZ (KERNEL_XZ) 5. LZO (KERNEL_LZO) 6. LZ4 (KERNEL_LZ4) 7. ZSTD (KERNEL_ZSTD) choice[1-7?]: 1 Default init path (DEFAULT_INIT) [] Default hostname (DEFAULT_HOSTNAME) [(none)] (none) System V IPC (SYSVIPC) [Y/n/?] y POSIX Message Queues (POSIX_MQUEUE) [Y/n/?] y General notification queue (WATCH_QUEUE) [Y/n/?] y Enable process_vm_readv/writev syscalls (CROSS_MEMORY_ATTACH) [Y/n/?] y uselib syscall (for libc5 and earlier) (USELIB) [N/y/?] n Auditing support (AUDIT) [Y/?] y Preemption Model 1. No Forced Preemption (Server) (PREEMPT_NONE) 2. Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY) > 3. Preemptible Kernel (Low-Latency Desktop) (PREEMPT) 4. Scheduler controlled preemption model (PREEMPT_LAZY) choice[1-4?]: 3 Fully Preemptible Kernel (Real-Time) (PREEMPT_RT) [N/y/?] n Preemption behaviour defined on boot (PREEMPT_DYNAMIC) [Y/n/?] y Core Scheduling for SMT (SCHED_CORE) [Y/n/?] y CPU isolation (CPU_ISOLATION) [Y/n/?] y Kernel .config support (IKCONFIG) [Y/n/m/?] y Enable access to .config through /proc/config.gz (IKCONFIG_PROC) [Y/n/?] y Enable kernel headers through /sys/kernel/kheaders.tar.xz (IKHEADERS) [N/m/y/?] n Kernel log buffer size (16 => 64KB, 17 => 128KB) (LOG_BUF_SHIFT) [18] 18 CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB) (LOG_CPU_MAX_BUF_SHIFT) [12] 12 Printk indexing debugfs interface (PRINTK_INDEX) [N/y/?] n Memory placement aware NUMA scheduler (NUMA_BALANCING) [Y/n/?] y Automatically enable NUMA aware memory/task placement (NUMA_BALANCING_DEFAULT_ENABLED) [Y/n/?] y Checkpoint/restore support (CHECKPOINT_RESTORE) [Y/n/?] y Automatic process group scheduling (SCHED_AUTOGROUP) [N/y/?] n Kernel->user space relay support (formerly relayfs) (RELAY) [Y/?] y Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD) [Y/n/?] y Initramfs source file(s) (INITRAMFS_SOURCE) [] Support initial ramdisk/ramfs compressed using gzip (RD_GZIP) [Y/n/?] y Support initial ramdisk/ramfs compressed using bzip2 (RD_BZIP2) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZMA (RD_LZMA) [Y/n/?] y Support initial ramdisk/ramfs compressed using XZ (RD_XZ) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZO (RD_LZO) [Y/n/?] y Support initial ramdisk/ramfs compressed using LZ4 (RD_LZ4) [Y/n/?] y Support initial ramdisk/ramfs compressed using ZSTD (RD_ZSTD) [Y/n/?] y Boot config support (BOOT_CONFIG) [N/y/?] n Preserve cpio archive mtimes in initramfs (INITRAMFS_PRESERVE_MTIME) [Y/n/?] y Compiler optimization level > 1. Optimize for performance (-O2) (CC_OPTIMIZE_FOR_PERFORMANCE) 2. Optimize for size (-Os) (CC_OPTIMIZE_FOR_SIZE) choice[1-2?]: 1 Enable madvise/fadvise syscalls (ADVISE_SYSCALLS) [Y/n/?] y Enable membarrier() system call (MEMBARRIER) [Y/?] y Enable kcmp() system call (KCMP) [Y/?] y Enable rseq() system call (RSEQ) [Y/n/?] y Enable debugging of rseq() system call (DEBUG_RSEQ) [N/y/?] n Enable cachestat() system call (CACHESTAT_SYSCALL) [Y/n/?] y PC/104 support (PC104) [N/y/?] n Load all symbols for debugging/ksymoops (KALLSYMS) [Y/?] y Test the basic functions and performance of kallsyms (KALLSYMS_SELFTEST) [N/y/?] n Include all symbols in kallsyms (KALLSYMS_ALL) [Y/?] y Profiling support (PROFILING) [Y/n/?] y Rust support (RUST) [N/y/?] (NE

▶ ▼ Discussions (1)

Title	Replies (including bot)	Last reply
[syzbot] [kernel?] INFO: rcu detected stall in kthread_worker_fn (2)	0 (1)	2025/03/13 09:29

▶ ▼ Similar bugs (1)

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: rcu detected stall in kthread_worker_fn kernel	1				12	570d	794d	0/29	auto-obsoleted due to no activity on 2025/02/16 10:22

▶ ▼ Last patch testing requests (10)


Created	Duration	User	Patch	Repo	Result
2026/06/10 05:09	38m	retest repro		upstream	log
2026/06/10 05:08	24m	retest repro		upstream	log
2026/04/13 13:21	17m	retest repro		upstream	report log
2026/02/02 10:44	20m	retest repro		upstream	report log
2025/11/30 03:39	20m	retest repro		upstream	report log
2025/11/18 08:39	1h11m	retest repro		upstream	report log
2025/09/21 02:41	25m	retest repro		upstream	report log
2025/09/09 06:53	21m	retest repro		upstream	report log
2025/06/27 02:35	1h14m	retest repro		upstream	report log
2025/04/05 02:19	28m	retest repro		upstream	report log

▶ ▼ Fix bisection attempts (4)


Created	Duration	User	Patch	Repo	Result
2026/02/18 07:55	1m	bisect fix		upstream	error job log
2025/12/15 08:39	2h35m	bisect fix		upstream	OK (0) job log log
2025/07/12 19:27	5h19m	bisect fix		upstream	OK (0) job log log
2025/05/21 17:41	2h51m	bisect fix		upstream	OK (0) job log log

Sample crash report:

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=bbfc/1/0x4000000000000000 softirq=14781/14781 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=11189, q=106 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 20 Comm: rcu_exp_gp_kthr Not tainted 6.14.0-rc7-syzkaller-00137-g5fc319360819 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:469 [inline]
RIP: 0010:lock_is_held_type+0xf5/0x190 kernel/locking/lockdep.c:5924
Code: ee e8 cf 5a 25 f9 eb cb 31 db eb 1e 41 83 fe ff 74 13 31 c0 f6 43 22 03 0f 95 c0 31 db 44 39 f0 0f 94 c3 eb 05 bb 01 00 00 00 <48> c7 c7 00 c6 2a 8c e8 7f 1a 00 00 b8 ff ff ff ff 65 0f c1 05 62
RSP: 0018:ffffc90000007c28 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffff88801d69da00
RDX: ffff88801d69da00 RSI: ffff888027cac300 RDI: ffff88801d69e4f0
RBP: 0000000000000000 R08: ffffffff8a05262b R09: fffff52000000f7c
R10: dffffc0000000000 R11: fffff52000000f7c R12: 0000000000000046
R13: ffff88801d69da00 R14: 00000000ffffffff R15: ffff888027cac300
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000600 CR3: 000000002f914000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 lock_is_held include/linux/lockdep.h:249 [inline]
 advance_sched+0xcd/0xca0 net/sched/sch_taprio.c:925
 __run_hrtimer kernel/time/hrtimer.c:1801 [inline]
 __hrtimer_run_queues+0x59d/0xd30 kernel/time/hrtimer.c:1865
 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1927
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x112/0x420 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xd8/0x140 kernel/locking/spinlock.c:194
Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 4e 59 1d f6 f6 44 24 21 02 75 52 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> b3 bc 83 f5 65 8b 05 a4 0f f8 73 85 c0 74 43 48 c7 04 24 0e 36
RSP: 0018:ffffc90000197820 EFLAGS: 00000206
RAX: 85548c2d7975cc00 RBX: 1ffff92000032f08 RCX: ffffffff9a654903
RDX: dffffc0000000000 RSI: ffffffff8c2ab3a0 RDI: 0000000000000001
RBP: ffffc900001978b0 R08: ffffffff903cfb77 R09: 1ffffffff2079f6e
R10: dffffc0000000000 R11: fffffbfff2079f6f R12: dffffc0000000000
R13: 1ffff92000032f04 R14: ffffc90000197840 R15: 0000000000000246
 debug_object_assert_init+0x2dd/0x4b0 lib/debugobjects.c:1009
 debug_timer_assert_init kernel/time/timer.c:845 [inline]
 debug_assert_init kernel/time/timer.c:890 [inline]
 __try_to_del_timer_sync+0x29/0x390 kernel/time/timer.c:1499
 __timer_delete_sync+0x245/0x310 kernel/time/timer.c:1662
 del_timer_sync include/linux/timer.h:185 [inline]
 schedule_timeout+0x162/0x290 kernel/time/sleep_timeout.c:100
 synchronize_rcu_expedited_wait_once kernel/rcu/tree_exp.h:543 [inline]
 synchronize_rcu_expedited_wait kernel/rcu/tree_exp.h:656 [inline]
 rcu_exp_wait_wake kernel/rcu/tree_exp.h:685 [inline]
 rcu_exp_sel_wait_wake+0x779/0x1dc0 kernel/rcu/tree_exp.h:719
 kthread_worker_fn+0x4f9/0xb70 kernel/kthread.c:1010
 kthread+0x7ab/0x920 kernel/kthread.c:464
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g11189 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=3110
rcu: rcu_preempt kthread starved for 10502 jiffies! g11189 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:26104 pid:18    tgid:18    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2024
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2226
 kthread+0x7ab/0x920 kernel/kthread.c:464
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Crashes (18):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2025/03/21 06:14	upstream	5fc319360819	62330552	.config	console log	report	syz / log			[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2025/03/09 09:16	upstream	b7c90e3e717a	163f510d	.config	console log	report	syz / log			[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-smack-root	INFO: rcu detected stall in kthread_worker_fn
2026/05/17 05:57	upstream	6916d5703ddf	de5aae85	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2026/05/07 08:11	upstream	5862221fdded	f250db59	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2026/04/23 08:45	upstream	2a4c0c11c019	b10da5ec	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2026/04/22 20:15	upstream	6596a02b2078	4595e353	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2025/12/28 17:14	upstream	d26143bb38e2	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2025/10/27 20:12	upstream	fd57572253bc	fd2207e7	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2025/08/26 06:16	upstream	fab1beda7597	bf27483f	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn
2025/06/12 11:09	upstream	2c4a1f3fe03e	98683f8f	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce	INFO: rcu detected stall in kthread_worker_fn
2025/04/16 10:27	upstream	1a1d569a75f3	23b969b7	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-selinux-root	INFO: rcu detected stall in kthread_worker_fn
2025/03/11 01:25	upstream	4d872d51bc9d	16256247	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-selinux-root	INFO: rcu detected stall in kthread_worker_fn
2025/03/02 18:55	upstream	1973160c90d7	c3901742	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-smack-root	INFO: rcu detected stall in kthread_worker_fn
2026/05/26 13:11	net-next	3baa7ba4ab98	a3e47276	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	INFO: rcu detected stall in kthread_worker_fn
2026/01/19 06:53	net-next	b4e486e2c46f	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	INFO: rcu detected stall in kthread_worker_fn
2026/01/12 12:44	net-next	60d8484c4cec	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	INFO: rcu detected stall in kthread_worker_fn
2026/01/11 15:12	net-next	60d8484c4cec	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	INFO: rcu detected stall in kthread_worker_fn
2025/10/13 20:15	linux-next	52ba76324a9d	b6605ba8	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-linux-next-kasan-gce-root	INFO: rcu detected stall in kthread_worker_fn

* ~~Struck through~~ repros no longer work on HEAD.