syzbot

 sign-in | mailing list | source | docs
🐞 Open [853]
🐞 Fixed [87]
🐞 Invalid [1356]
⬇ Missing Backports [132]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in mmap_file

Status: auto-obsoleted due to no activity on 2025/04/01 14:21
Reported-by: syzbot+bbb3ed7be73ead93dd43@syzkaller.appspotmail.com
First crash: 541d, last: 541d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in mmap_file (3) 1 3 105d 276d 0/3 auto-obsoleted due to no activity on 2026/06/11 12:22
linux-5.15 INFO: rcu detected stall in mmap_file (4) 1 1 2d16h 2d16h 0/3 upstream: reported on 2026/06/14 00:35
linux-6.1 INFO: rcu detected stall in mmap_file 1 1 19d 19d 0/3 upstream: reported on 2026/05/27 21:33
linux-5.15 INFO: rcu detected stall in mmap_file (2) 1 1 386d 386d 0/3 auto-obsoleted due to no activity on 2025/09/02 23:08

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=3cb/1/0x4000000000000000 softirq=44103/44104 fqs=130 
	(detected by 1, t=10505 jiffies, g=49677, q=770)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14683 Comm: syz.3.2125 Not tainted 5.15.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:_raw_spin_unlock_irqrestore+0xd/0x130 kernel/locking/spinlock.c:193
Code: f7 65 8b 05 1d e3 b9 75 85 c0 74 02 5b c3 e8 ea ff b7 f6 5b c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41 56 41 55 41 54 53 <48> 83 e4 e0 48 83 ec 60 49 89 f7 48 89 fb 65 48 8b 04 25 28 00 00
RSP: 0018:ffffc90000007d28 EFLAGS: 00000046
RAX: 1ffff1100ea3786d RBX: ffff8880751bc368 RCX: 0000000000000001
RDX: 0000000000010000 RSI: 0000000000000046 RDI: ffff8880b8e2a200
RBP: ffffc90000007d50 R08: ffffffff816f8850 R09: fffffbfff1c14c0e
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880b8e2a200
R13: ffffffff888c5670 R14: ffff8880751bc340 R15: dffffc0000000000
FS:  00005555714d1500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f430ff0cf98 CR3: 0000000025734000 CR4: 00000000003506f0
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 __run_hrtimer kernel/time/hrtimer.c:1684 [inline]
 __hrtimer_run_queues+0x48c/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x7b/0x290 mm/kasan/generic.c:189
Code: 00 00 00 00 fc ff df 4f 8d 34 1a 4c 89 f5 4c 29 cd 48 83 fd 10 7f 26 48 85 ed 0f 84 3a 01 00 00 49 f7 d2 49 01 da 41 80 39 00 <0f> 85 c4 01 00 00 49 ff c1 49 ff c2 75 ee e9 1d 01 00 00 45 89 cf
RSP: 0018:ffffc90002ecf3f8 EFLAGS: 00000246
RAX: ffffffff81d10c01 RBX: 1ffff920005d9e90 RCX: ffffffff81d10c36
RDX: 0000000000000001 RSI: 0000000000000080 RDI: ffffc90002ecf480
RBP: 0000000000000010 R08: dffffc0000000000 R09: fffff520005d9e97
R10: fffffffffffffff7 R11: dffffc0000000001 R12: dffffc0000000000
R13: 1ffff920005d9e8c R14: fffff520005d9ea0 R15: 0000000000102dc2
 memset+0x1f/0x40 mm/kasan/shadow.c:44
 save_stack+0x86/0x1e0 mm/page_owner.c:103
 __set_page_owner+0x37/0x300 mm/page_owner.c:181
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x3b78/0x3d40 mm/page_alloc.c:4192
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5465
 vm_area_alloc_pages mm/vmalloc.c:2868 [inline]
 __vmalloc_area_node mm/vmalloc.c:2924 [inline]
 __vmalloc_node_range+0x5ab/0x8c0 mm/vmalloc.c:3029
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3165
 kcov_mmap+0x28/0x120 kernel/kcov.c:474
 call_mmap include/linux/fs.h:2179 [inline]
 mmap_file+0x5a/0xb0 mm/util.c:1092
 __mmap_region mm/mmap.c:1784 [inline]
 mmap_region+0x1035/0x1870 mm/mmap.c:2921
 do_mmap+0x78d/0xe00 mm/mmap.c:1574
 vm_mmap_pgoff+0x1ca/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x559/0x780 mm/mmap.c:1623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f72620ddd63
Code: f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 41 89 ca 41 f7 c1 ff 0f 00 00 75 14 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 25 c3 0f 1f 40 00 48 c7 c0 a8 ff ff ff 64 c7
RSP: 002b:00007ffda3c05938 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f72622ce2d8 RCX: 00007f72620ddd63
RDX: 0000000000000003 RSI: 0000000000400000 RDI: 00007f725faeb000
RBP: 00007f72622ce240 R08: 00000000000000db R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f72622ce240 R14: 0000000000000003 R15: 0000000000000076
 </TASK>
rcu: rcu_preempt kthread starved for 9830 jiffies! g49677 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:26816 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 4745 Comm: kworker/u4:12 Not tainted 5.15.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline]
RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline]
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xa91/0xd90 kernel/smp.c:969
Code: 0f b6 04 03 84 c0 0f 85 84 00 00 00 45 8b 7d 00 44 89 fe 83 e6 01 31 ff e8 3c d6 0b 00 41 83 e7 01 75 07 e8 d1 d2 0b 00 eb 41 <f3> 90 48 b8 00 00 00 00 00 fc ff df 0f b6 04 03 84 c0 75 11 41 f7
RSP: 0018:ffffc90002fde500 EFLAGS: 00000293
RAX: ffffffff8174b234 RBX: 1ffff110171c8541 RCX: ffff88802aaed940
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90002fde640 R08: ffffffff8174b204 R09: ffffed10171c7679
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000
R13: ffff8880b8e42a08 R14: ffff8880b8f3b380 R15: 0000000000000001
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1135
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:87 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:900 [inline]
 flush_tlb_mm_range+0x2a5/0x4a0 arch/x86/mm/tlb.c:986
 flush_tlb_page arch/x86/include/asm/tlbflush.h:239 [inline]
 ptep_clear_flush+0x112/0x150 mm/pgtable-generic.c:97
 page_mkclean_one+0x428/0x7b0 mm/rmap.c:938
 rmap_walk_file+0x3f8/0x600 mm/rmap.c:2378
 rmap_walk mm/rmap.c:2396 [inline]
 page_mkclean+0x330/0x490 mm/rmap.c:1006
 clear_page_dirty_for_io+0x3ce/0xa60 mm/page-writeback.c:2749
 mpage_submit_page+0x90/0x230 fs/ext4/inode.c:2092
 mpage_process_page_bufs+0x6c8/0x8b0 fs/ext4/inode.c:2226
 mpage_prepare_extent_to_map+0xc9d/0x1150 fs/ext4/inode.c:2654
 ext4_writepages+0xcd0/0x3d10 fs/ext4/inode.c:2782
 do_writepages+0x481/0x730 mm/page-writeback.c:2386
 __writeback_single_inode+0x15b/0xe30 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930
 __writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001
 wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106
 wb_check_old_data_flush fs/fs-writeback.c:2206 [inline]
 wb_do_writeback fs/fs-writeback.c:2259 [inline]
 wb_workfn+0xc55/0x1130 fs/fs-writeback.c:2288
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/22 14:21 linux-5.15.y 91786f140358 b4fbdbd4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in mmap_file
* Struck through repros no longer work on HEAD.