INFO: rcu detected stall in blkdev_write

ID	Workflow	Result	Correct	Bug	Created	Started	Finished	Revision	Error
175dead3	assessment-security	DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌	❓	INFO: rcu detected stall in blkdev_write_iter (2)	2026/05/22 23:25	2026/05/22 23:25	2026/05/23 00:31	df8ac09c

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	INFO: rcu detected stall in blkdev_write_iter cgroups mm block	1				3	464d	586d	0/29	auto-obsoleted due to no activity on 2025/07/23 16:46

Kernel

Title

Rank 🛈

upstream

INFO: rcu detected stall in blkdev_write_iter cgroups mm block

464d

586d

0/29

auto-obsoleted due to no activity on 2025/07/23 16:46

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P16659/2:b..l P16655/1:b..l rcu: (detected by 1, t=10502 jiffies, g=152465, q=1520 ncpus=2) task:syz.2.2228 state:R running task stack:26376 pid:16655 tgid:16654 ppid:5832 task_flags:0x400140 flags:0x00080002 Call Trace: <TASK> context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 fb 24 2e 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 c6 be f7 0e 0f 82 a4 02 00 00 8b 35 2e f2 f7 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 24 2e 12 0f 85 ed 02 00 00 48 83 c4 RSP: 0018:ffffc900037971d0 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8df26864 RDI: ffffffff8c1bf100 RBP: ffffffff8e7e6de0 R08: 00000000e75d0f49 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905 alloc_buffer_head+0x21/0x140 fs/buffer.c:2934 folio_alloc_buffers+0x274/0x820 fs/buffer.c:832 create_empty_buffers+0x3a/0x660 fs/buffer.c:1581 folio_create_buffers+0x13b/0x1a0 fs/buffer.c:1692 __block_write_begin_int+0x393/0x19c0 fs/buffer.c:2016 iomap_write_begin+0x1664/0x2340 fs/iomap/buffered-io.c:1014 iomap_write_iter fs/iomap/buffered-io.c:1144 [inline] iomap_file_buffered_write+0x48b/0xac0 fs/iomap/buffered-io.c:1225 blkdev_buffered_write block/fops.c:735 [inline] blkdev_write_iter+0x575/0xd70 block/fops.c:801 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbe3ef9c819 RSP: 002b:00007fbe3fde2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fbe3f215fa0 RCX: 00007fbe3ef9c819 RDX: 0000000080000000 RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007fbe3f032c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbe3f216038 R14: 00007fbe3f215fa0 R15: 00007fff5ad93078 </TASK> task:syz.2.2228 state:R running task stack:25192 pid:16659 tgid:16654 ppid:5832 task_flags:0x20440140 flags:0x00080003 Call Trace: <TASK> context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 fb 24 2e 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 c6 be f7 0e 0f 82 a4 02 00 00 8b 35 2e f2 f7 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 24 2e 12 0f 85 ed 02 00 00 48 83 c4 RSP: 0018:ffffc90003a56950 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff8df26864 RDI: ffffffff8c1bf100 RBP: ffffffff8e7e6de0 R08: 00000000ea80e6f5 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:838 [inline] class_rcu_constructor include/linux/rcupdate.h:1181 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556 slab_free_hook mm/slub.c:2650 [inline] slab_free mm/slub.c:6246 [inline] kmem_cache_free+0x433/0x6c0 mm/slub.c:6373 mempool_free+0xde/0x130 mm/mempool.c:711 bio_put_percpu_cache block/bio.c:822 [inline] bio_put+0x34f/0x5b0 block/bio.c:841 mpage_read_end_io+0x34e/0x830 fs/mpage.c:53 bio_endio+0x78f/0x8f0 block/bio.c:1794 blk_update_request+0x741/0x1380 block/blk-mq.c:1016 blk_mq_end_request+0x5b/0x420 block/blk-mq.c:1178 blk_mq_complete_request block/blk-mq.c:1356 [inline] blk_mq_complete_request+0x8b/0xb0 block/blk-mq.c:1353 nullb_complete_cmd drivers/block/null_blk/main.c:1412 [inline] null_handle_cmd drivers/block/null_blk/main.c:1464 [inline] null_queue_rq+0xb48/0xfb0 drivers/block/null_blk/main.c:1703 null_queue_rqs+0xe9/0x2f0 drivers/block/null_blk/main.c:1717 __blk_mq_flush_list block/blk-mq.c:2858 [inline] __blk_mq_flush_list+0x9a/0xc0 block/blk-mq.c:2854 blk_mq_dispatch_queue_requests+0x184/0x7c0 block/blk-mq.c:2903 blk_mq_flush_plug_list+0x1f2/0x600 block/blk-mq.c:2991 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug+0x5c/0xa0 block/blk-core.c:1257 read_pages+0x5f7/0xdf0 mm/readahead.c:176 page_cache_ra_order+0x76b/0xf10 mm/readahead.c:521 page_cache_async_ra+0x7bb/0xd30 mm/readahead.c:700 do_async_mmap_readahead mm/filemap.c:3441 [inline] filemap_fault+0xf77/0x2e90 mm/filemap.c:3540 __do_fault+0x10b/0x440 mm/memory.c:5458 do_read_fault mm/memory.c:5893 [inline] do_fault+0xa99/0x1750 mm/memory.c:6027 do_pte_missing mm/memory.c:4550 [inline] handle_pte_fault mm/memory.c:6411 [inline] __handle_mm_fault+0x187d/0x2a00 mm/memory.c:6549 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718 faultin_page mm/gup.c:1126 [inline] __get_user_pages+0x1178/0x32a0 mm/gup.c:1428 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1860 __mm_populate+0x107/0x3a0 mm/gup.c:1963 mm_populate include/linux/mm.h:4135 [inline] vm_mmap_pgoff+0x37f/0x470 mm/util.c:586 ksys_mmap_pgoff+0x3cb/0x610 mm/mmap.c:606 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbe3ef9c819 RSP: 002b:00007fbe3fda0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007fbe3f216180 RCX: 00007fbe3ef9c819 RDX: 0000000000000ffb RSI: 0000000000810006 RDI: 0000000000000000 RBP: 00007fbe3f032c91 R08: 0000000000000003 R09: 0000000000000000 R10: 0008000000008011 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbe3f216218 R14: 00007fbe3f216180 R15: 00007fff5ad93078 </TASK> rcu: rcu_preempt kthread starved for 1231 jiffies! g152465 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:27920 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: <TASK> context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7282 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: f6 8b 02 e9 83 42 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 23 7b 17 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000197df0 EFLAGS: 00000242 RAX: 000000000085ed45 RBX: ffff88801eaa8000 RCX: ffffffff8b941045 RDX: 0000000000000000 RSI: ffffffff8df4bca9 RDI: ffffffff8c1bf100 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed10170a67ad R10: ffff8880b8533d6b R11: 0000000000000000 R12: 0000000000000001 R13: ffffed1003d55000 R14: 0000000000000001 R15: ffffffff90dbea10 FS: 0000000000000000(0000) GS:ffff8881243fb000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe84cebedd0 CR3: 0000000075abc000 CR4: 00000000003526f0 Call Trace: <TASK> arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline] default_idle+0x9/0x10 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x464/0x590 kernel/sched/idle.c:352 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x148 </TASK>

Crashes (6):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Assets (help?)	Manager	Title
2026/04/17 20:20	upstream	43cfbdda5af6	24ecfc1e	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-qemu-gce-upstream-auto	INFO: rcu detected stall in blkdev_write_iter
2026/03/22 18:46	upstream	113ae7b4decc	5b92003d	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-qemu-gce-upstream-auto	INFO: rcu detected stall in blkdev_write_iter
2025/12/28 00:26	upstream	c53f467229a7	d6526ea3	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-selinux-root	INFO: rcu detected stall in blkdev_write_iter
2025/12/08 07:10	upstream	67a454e6b1c6	d6526ea3	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-selinux-root	INFO: rcu detected stall in blkdev_write_iter
2025/09/20 16:26	upstream	cd89d487374c	67c37560	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-qemu-gce-upstream-auto	INFO: rcu detected stall in blkdev_write_iter
2025/11/25 06:45	linux-next	422f3140bbcb	64219f15	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci-upstream-linux-next-kasan-gce-root	INFO: rcu detected stall in blkdev_write_iter

Crashes (6):

Assets (help?)