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BUG: workqueue leaked atomic, lock or RCU: kworker/u8:NUM[NUM] (2)

Status: moderation: reported on 2026/04/26 21:39
Subsystems: arm
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+1c62954c54045eda50cb@syzkaller.appspotmail.com
First crash: 48d, last: 48d
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
e47e5405-8883-4931-abdf-1f15072cf046 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ BUG: workqueue leaked atomic, lock or RCU: kworker/u8:NUM[NUM] (2) 2026/06/02 12:02 2026/06/02 12:02 2026/06/02 12:55 1095583bae1d2729a3b4be301cb6ddc85ced9e38
e71d3328-53bc-479e-be2e-798d11f12587 assessment-security 💥 BUG: workqueue leaked atomic, lock or RCU: kworker/u8:NUM[NUM] (2) 2026/05/24 21:50 2026/05/24 21:50 2026/05/24 23:23 c69befb30ac10e158cc9d1557b508ee3f0eca1de request failed with 500 Internal Server Error: method "ai_trajectory_log" ns "" err: spanner: code = "DeadlineExceeded", desc = "context deadline exceeded, transaction outcome unknown", requestID = "1.15002feac43365aa.1.3.336717.1" request: {AgentName:agent JobID:e71d3328-53bc-479e-be2e-798d11f12587 Span:finished tool codesearch-definition-source (2/61) in 3m47.377362595s results: SourceCode: 2564: int do_writepages(struct address_space *mapping, struct writeback_control *wbc) 2565: { 2566: int ret; 2567: struct bdi_writeback *wb; 2568: 2569: if (wbc->nr_to_write <= 0) 2570: return 0; 2571: wb = inode_to_wb_wbc(mapping->host, wbc); 2572: wb_bandwidth_estimate_start(wb); 2573: while (1) { 2574: if (mapping->a_ops->writepages) 2575: ret = mapping->a_ops->writepages(mapping, wbc); 2576: else 2577: /* deal with chardevs and other special files */ 2578: ret = 0; 2579: if (ret != -ENOMEM || wbc->sync_mode != WB_SYNC_ALL) 2580: break; 2581: 2582: /* 2583: * Lacking an allocation context or the locality or writeback 2584: * state of any of the inode's pages, throttle based on 2585: * writeback activity on the local node. It's as good a 2586: * guess as any. 2587: */ 2588: reclaim_throttle(NODE_DATA(numa_node_id()), 2589: VMSCAN_THROTTLE_WRITEBACK); 2590: } 2591: /* 2592: * Usually few pages are written by now from those we've just submitted 2593: * but if there's constant writeback being submitted, this makes sure 2594: * writeback bandwidth is updated once in a while. 2595: */ 2596: if (time_is_before_jiffies(READ_ONCE(wb->bw_time_stamp) + 2597: BANDWIDTH_INTERVAL)) 2598: wb_update_bandwidth(wb); 2599: return ret; 2600: } SourceFile: mm/page-writeback.c }
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: workqueue leaked atomic, lock or RCU: kworker/u8:NUM[NUM] batman -1 1 337d 333d 0/29 auto-obsoleted due to no activity on 2025/10/06 01:42

Sample crash report:
BUG: workqueue leaked atomic, lock or RCU: kworker/u8:7[957]
     preempt=0x00000000 lock=0->0 RCU=0->124 workfn=wb_workfn
CPU: 1 UID: 0 PID: 957 Comm: kworker/u8:7 Not tainted syzkaller #0 PREEMPT 
Hardware name: ARM-Versatile Express
Workqueue: writeback wb_workfn (flush-253:0)
Call trace: 
[<80201a14>] (dump_backtrace) from [<80201b08>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:60000013 r6:60000013 r5:8231c0d0 r4:00000000
[<80201af0>] (show_stack) from [<8021e320>] (__dump_stack lib/dump_stack.c:94 [inline])
[<80201af0>] (show_stack) from [<8021e320>] (dump_stack_lvl+0x5c/0x70 lib/dump_stack.c:120)
[<8021e2c4>] (dump_stack_lvl) from [<8021e34c>] (dump_stack+0x18/0x1c lib/dump_stack.c:129)
 r7:83012a00 r6:83801200 r5:84265554 r4:84127a00
[<8021e334>] (dump_stack) from [<802766a8>] (process_one_work+0x510/0x5a0 kernel/workqueue.c:3323)
[<80276198>] (process_one_work) from [<80277124>] (process_scheduled_works kernel/workqueue.c:3385 [inline])
[<80276198>] (process_one_work) from [<80277124>] (worker_thread+0x16c/0x318 kernel/workqueue.c:3466)
 r10:00000000 r9:84127a30 r8:833de200 r7:82a03d80 r6:83012a20 r5:83012a00
 r4:84127a00
[<80276fb8>] (worker_thread) from [<8028117c>] (kthread+0x11c/0x154 kernel/kthread.c:436)
 r10:00000000 r9:df849e88 r8:844da480 r7:84127a00 r6:80276fb8 r5:833de200
 r4:84131f40
[<80281060>] (kthread) from [<80200114>] (ret_from_fork+0x14/0x20 arch/arm/kernel/entry-common.S:137)
Exception stack(0xe0449fb0 to 0xe0449ff8)
9fa0:                                     00000000 00000000 00000000 00000000
9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80281060 r4:84131f40
------------[ cut here ]------------
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x4ac/0x638 kernel/rcu/tree_plugin.h:332, CPU#1: kworker/u8:7/957
Voluntary context switch within RCU read-side critical section!
Modules linked in:

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/22 21:37 upstream 2a4c0c11c019 0e869ba2 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm32 BUG: workqueue leaked atomic, lock or RCU: kworker/u8:NUM[NUM]
* Struck through repros no longer work on HEAD.