syzbot

 sign-in | mailing list | source | docs | 🏰
🐞 Open [1350]
≡ Subsystems
🐞 Fixed [7124]
🐞 Invalid [18843]
⬇ Missing Backports [220]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
✨ AI
💬 Send us feedback

INFO: rcu detected stall in task_numa_work (2)

Status: upstream: reported C repro on 2025/01/04 04:47
Subsystems: bpf mm
[Documentation on labels]
Reported-by: syzbot+06d48cbf3e767907cec2@syzkaller.appspotmail.com
First crash: 734d, last: 10d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
1fb2db51-03e4-418b-ba8a-550562bb9291 assessment-security 💥 INFO: rcu detected stall in task_numa_work (2) 2026/05/23 23:09 2026/05/23 23:09 2026/05/23 23:35 c69befb30ac10e158cc9d1557b508ee3f0eca1de 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/83d3f0de0bb0b972f0c3cb1ca312e0851fe23340" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General architecture-dependent options * Kprobes (KPROBES) [N/y/?] n Optimize very unlikely/likely branches (JUMP_LABEL) [Y/n/?] y Static key selftest (STATIC_KEYS_SELFTEST) [N/y/?] n Static call selftest (STATIC_CALL_SELFTEST) [N/y/?] n Enable seccomp to safely execute untrusted bytecode (SECCOMP) [Y/n/?] y Show seccomp filter cache status in /proc/pid/seccomp_cache (SECCOMP_CACHE_DEBUG) [N/y/?] n Stack Protector buffer overflow detection (STACKPROTECTOR) [Y/n/?] y Strong Stack Protector (STACKPROTECTOR_STRONG) [Y/n/?] y Link Time Optimization (LTO) > 1. None (LTO_NONE) choice[1]: 1 Enable Clang's AutoFDO build (EXPERIMENTAL) (AUTOFDO_CLANG) [N/y/?] (NEW) Error in reading or end of file. Enable Clang's Propeller build (PROPELLER_CLANG) [N/y/?] (NEW) Error in reading or end of file. Use Clang's Control Flow Integrity (CFI) (CFI_CLANG) [N/y/?] (NEW) Error in reading or end of file. Number of bits to use for ASLR of mmap base address (ARCH_MMAP_RND_BITS) [28] 28 Number of bits to use for ASLR of mmap base address for compatible applications (ARCH_MMAP_RND_COMPAT_BITS) [8] 8 MMU page size > 1. 4KiB pages (PAGE_SIZE_4KB) choice[1]: 1 Provide system calls for 32-bit time_t (COMPAT_32BIT_TIME) [Y/n/?] y Use a virtually-mapped stack (VMAP_STACK) [Y/n/?] y Support for randomizing kernel stack offset on syscall entry (RANDOMIZE_KSTACK_OFFSET) [Y/n/?] y Default state of kernel stack offset randomization (RANDOMIZE_KSTACK_OFFSET_DEFAULT) [N/y/?] n Locking event counts collection (LOCK_EVENT_COUNTS) [N/y/?] n * * Memory initialization * Initialize kernel stack variables at function entry 1. no automatic stack variable initialization (weakest) (INIT_STACK_NONE) 2. pattern-init everything (strongest) (INIT_STACK_ALL_PATTERN) > 3. zero-init everything (strongest and safest) (INIT_STACK_ALL_ZERO) choice[1-3?]: 3 Enable heap memory zeroing on allocation by default (INIT_ON_ALLOC_DEFAULT_ON) [Y/n/?] y Enable heap memory zeroing on free by default (INIT_ON_FREE_DEFAULT_ON) [N/y/?] n Enable register zeroing on function exit (ZERO_CALL_USED_REGS) [N/y/?] (NEW) Error in reading or end of file. * * Kernel hardening options * Randomize layout of sensitive kernel structures > 1. Disable structure layout randomization (RANDSTRUCT_NONE) 2. Fully randomize structure layout (RANDSTRUCT_FULL) (NEW) choice[1-2?]: Error in reading or end of file. * * Compile-time checks and compiler options * Debug information 1. Disable debug information (DEBUG_INFO_NONE) 2. Rely on the toolchain's implicit default DWARF version (DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT) > 3. Generate DWARF Version 4 debuginfo (DEBUG_INFO_DWARF4) 4. Generate DWARF Version 5 debuginfo (DEBUG_INFO_DWARF5) choice[1-4?]: 3 Reduce debugging information (DEBUG_INFO_REDUCED) [N/y/?] n Compressed Debug information > 1. Don't compress debug information (DEBUG_INFO_COMPRESSED_NONE) 2. Compress debugging information with zlib (DEBUG_INFO_COMPRESSED_ZLIB) 3. Compress debugging information with zstd (DEBUG_INFO_COMPRESSED_ZSTD) (NEW) choice[1-3?]: Error in reading or end of file. Produce split debuginfo in .dwo files (DEBUG_INFO_SPLIT) [N/y/?] n Generate BTF type information (DEBUG_INFO_BTF) [N/y/?] n Provide GDB scripts for kernel debugging (GDB_SCRIPTS) [N/y/?] n Warn for stack frames larger than (FRAME_WARN) [2048] 2048 Strip assembler-generated symbols during link (STRIP_ASM_SYMS) [N/y/?] n Install uapi headers to usr/include (HEADERS_INSTALL) [N/y/?] n Make section mismatch errors non-fatal (SECTION_MISMATCH_WARN_ONLY) [Y/n/?] y Force all function address 64B aligned (DEBUG_FORCE_FUNCTION_ALIGN_64B) [N/y/?] n Generate vmlinux.map file when linking (VMLINUX_MAP) [N/y/?] n Force weak per-cpu definitions (DEBUG_FOR
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[syzbot] Monthly bpf report (May 2026) 0 (1) 2026/05/18 04:32
[syzbot] Monthly bpf report (Feb 2026) 0 (1) 2026/02/06 14:30
[syzbot] [mm?] INFO: rcu detected stall in task_numa_work (2) 0 (1) 2025/01/04 04:47
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in task_numa_work mm 1 2 1004d 1005d 0/29 auto-obsoleted due to no activity on 2023/11/28 14:56
linux-6.1 INFO: rcu detected stall in task_numa_work 1 1 725d 725d 0/3 auto-obsoleted due to no activity on 2024/09/12 14:33
linux-4.19 BUG: soft lockup in task_numa_work 1 1 1640d 1640d 0/1 auto-closed as invalid on 2022/04/01 16:00
▶ ▼ Last patch testing requests (7)
Created Duration User Patch Repo Result
2026/04/22 07:11 49m retest repro net-next report log
2026/02/11 06:29 32m retest repro net-next report log
2026/02/11 06:24 21m retest repro net-next report log
2025/12/03 05:24 59m retest repro net-next report log
2025/09/23 23:39 25m retest repro net-next report log
2025/07/15 22:47 21m retest repro net-next report log
2025/01/16 00:14 21m retest repro net-next report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2025/05/06 10:23 12h04m bisect fix net-next error job log
2025/03/24 01:15 3h15m bisect fix net-next OK (0) job log log
2025/02/19 22:41 3h31m bisect fix net-next OK (0) job log log

Sample crash report:
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5865/2:b..l
rcu: 	(detected by 0, t=10503 jiffies, g=7645, q=122 ncpus=2)
task:syz-executor118 state:R  running task     stack:19936 pid:5865  tgid:5865  ppid:5860   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7078
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5853
Code: 2b 00 74 08 4c 89 f7 e8 9a 23 8b 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc9000408f3c0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000811e84 RCX: ffff88807ef5c6d8
RDX: dffffc0000000000 RSI: ffffffff8c0aa960 RDI: ffffffff8c5faee0
RBP: ffffc9000408f510 R08: ffffffff942bc887 R09: 1ffffffff2857910
R10: dffffc0000000000 R11: fffffbfff2857911 R12: 1ffff92000811e80
R13: dffffc0000000000 R14: ffffc9000408f420 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 rcu_read_lock include/linux/rcupdate.h:849 [inline]
 is_bpf_text_address+0x46/0x2a0 kernel/bpf/core.c:772
 kernel_text_address+0xa7/0xe0 kernel/extable.c:125
 __kernel_text_address+0xd/0x40 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0xfd/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 save_stack+0xfb/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x76/0x430 mm/page_owner.c:297
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xd3f/0x1010 mm/page_alloc.c:2657
 discard_slab mm/slub.c:2688 [inline]
 __put_partials+0x160/0x1c0 mm/slub.c:3157
 put_cpu_partial+0x17c/0x250 mm/slub.c:3232
 __slab_free+0x290/0x380 mm/slub.c:4483
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_kmalloc+0x23/0xb0 mm/kasan/common.c:385
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 task_numa_work+0xad5/0x14b0 kernel/sched/fair.c:3407
 task_work_run+0x24f/0x310 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faf0e7f728a
RSP: 002b:00007ffc20bea148 EFLAGS: 00000286
 ORIG_RAX: 0000000000000106
RAX: 0000000000000000 RBX: 000000000000004a RCX: 00007faf0e7f728a
RDX: 00007ffc20bea170 RSI: 00007ffc20bea200 RDI: 00000000ffffff9c
RBP: 00007ffc20bea200 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000286 R12: 00007ffc20beb270
R13: 000055557d6a56c0 R14: 00007ffc20beb2b0 R15: 000000000000000d
 </TASK>
rcu: rcu_preempt kthread starved for 7869 jiffies! g7645 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:26264 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2045
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2247
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.13.0-rc3-syzkaller-00762-g9268abe611b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:get_current arch/x86/include/asm/current.h:49 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216
Code: 8b 3d 74 8f 8f 0c 48 89 de 5b e9 63 f0 5a 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 00 d6 03 00 65 8b 15 00 62 64 7e 81 e2 00 01 ff 00
RSP: 0018:ffffc90000156db8 EFLAGS: 00000246
RAX: ffffffff8a91fc9d RBX: 00000000000048e0 RCX: ffff88801cad5a00
RDX: ffff88801cad5a00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880b203a173 R08: ffffffff8a91fc92 R09: ffffffff8a91fa99
R10: 0000000000000003 R11: ffff88801cad5a00 R12: 0000000000000000
R13: ffff8881426b0800 R14: ffff888034f80e08 R15: ffff8881426b0818
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcd0e05e580 CR3: 000000000e736000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 br_flood+0x2cd/0x680 net/bridge/br_forward.c:232
 br_handle_frame_finish+0x18d2/0x2000 net/bridge/br_input.c:220
 br_nf_hook_thresh+0x472/0x590
 br_nf_pre_routing_finish_ipv6+0xaa0/0xdd0
 NF_HOOK include/linux/netfilter.h:314 [inline]
 br_nf_pre_routing_ipv6+0x379/0x770 net/bridge/br_netfilter_ipv6.c:184
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:282 [inline]
 br_handle_frame+0x9f3/0x1530 net/bridge/br_input.c:433
 __netif_receive_skb_core+0x14eb/0x4690 net/core/dev.c:5566
 __netif_receive_skb_one_core net/core/dev.c:5670 [inline]
 __netif_receive_skb+0x12f/0x650 net/core/dev.c:5785
 process_backlog+0x662/0x15b0 net/core/dev.c:6117
 __napi_poll+0xcb/0x490 net/core/dev.c:6883
 napi_poll net/core/dev.c:6952 [inline]
 net_rx_action+0x89b/0x1240 net/core/dev.c:7074
 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561
 run_ksoftirqd+0xca/0x130 kernel/softirq.c:950
 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (25):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/31 04:27 net-next 9268abe611b0 d3ccff63 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in task_numa_work
2026/01/27 17:54 upstream fcb70a56f4d8 9a514c2f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in task_numa_work
2025/11/05 17:34 upstream 1c353dc8d962 a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in task_numa_work
2025/10/11 09:36 upstream 0739473694c4 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in task_numa_work
2025/08/02 18:30 upstream 038d61fd6422 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in task_numa_work
2025/06/01 03:09 upstream 4cb6c8af8591 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in task_numa_work
2025/01/19 14:02 upstream fda5e3f28400 f2cb035c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in task_numa_work
2025/01/18 22:46 upstream fda5e3f28400 f2cb035c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in task_numa_work
2025/01/01 22:22 upstream 56e6a3499e14 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in task_numa_work
2024/12/27 20:21 upstream d6ef8b40d075 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in task_numa_work
2024/10/27 16:51 upstream 850925a8133c 65e8686b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in task_numa_work
2024/10/21 23:45 upstream 42f7652d3eb5 a93682b3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: rcu detected stall in task_numa_work
2024/08/31 20:00 upstream 1934261d8974 1eda0d14 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in task_numa_work
2024/06/24 04:29 upstream 7c16f0a4ed1c edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: rcu detected stall in task_numa_work
2024/06/23 13:45 upstream 5f583a3162ff edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in task_numa_work
2024/05/26 12:03 upstream c13320499ba0 a10a183e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: rcu detected stall in task_numa_work
2026/05/20 18:14 net dc416e32baae 62fb93a2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in task_numa_work
2026/03/12 12:24 net 87f7dff3ec75 4efadf07 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in task_numa_work
2024/11/21 06:22 net 66418447d27b 4b25d554 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: rcu detected stall in task_numa_work
2026/05/17 22:52 net-next 627ac78f2741 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in task_numa_work
2024/12/20 12:42 net-next b73e56f16250 1d58202c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in task_numa_work
2024/12/18 16:17 net-next c1bad69f8baf 1432fc84 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in task_numa_work
2024/12/06 18:25 net-next 51db5c894300 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in task_numa_work
2025/10/18 14:58 linux-next 93f3bab4310d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in task_numa_work
2024/09/30 05:51 linux-next cea5425829f7 ba29ff75 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in task_numa_work
* Struck through repros no longer work on HEAD.