syzbot


INFO: rcu detected stall in shmem_fault (2)

Status: upstream: reported on 2024/12/17 16:40
Reported-by: syzbot+ed7102c3fd41447141e8@syzkaller.appspotmail.com
First crash: 188d, last: 11d
Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in shmem_fault (4) kernel 1 905d 905d 0/29 auto-obsoleted due to no activity on 2023/04/08 07:17
linux-5.15 INFO: rcu detected stall in shmem_fault (2) 12 1d03h 384d 0/3 upstream: reported on 2024/06/03 20:13
upstream INFO: rcu detected stall in shmem_fault mm 13 2288d 2448d 0/29 closed as dup on 2019/01/02 16:58
linux-6.6 INFO: rcu detected stall in shmem_fault 1 6d20h 6d20h 0/2 upstream: reported on 2025/06/16 23:06
linux-6.1 INFO: rcu detected stall in shmem_fault 7 316d 381d 0/3 auto-obsoleted due to no activity on 2024/11/18 20:23
upstream INFO: rcu detected stall in shmem_fault (5) cgroups mm 3 675d 695d 23/29 fixed on 2023/10/12 12:48
linux-5.15 INFO: rcu detected stall in shmem_fault 1 660d 660d 0/3 auto-obsoleted due to no activity on 2023/12/11 11:17
upstream INFO: rcu detected stall in shmem_fault (3) fs mm 4 1154d 1154d 0/29 auto-closed as invalid on 2022/06/25 08:10
upstream INFO: rcu detected stall in shmem_fault (2) cgroups mm 1 2028d 2028d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in shmem_fault (6) mm C 116 1d00h 277d 0/29 upstream: reported C repro on 2024/09/19 14:28

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4426/1:b..l
	(detected by 0, t=10502 jiffies, g=11653, q=142 ncpus=2)
task:syz.1.19        state:R  running task     stack:25248 pid:4426  ppid:4254   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_is_watching+0x63/0xa0 kernel/rcu/tree.c:722
Code: 89 f7 e8 60 48 67 00 48 c7 c3 a8 57 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 2f 8b 03 65 ff 0d 55 68 97 7e <74> 0c 83 e0 04 c1 e8 02 5b 41 5e 41 5f c3 e8 b2 79 95 ff eb ed 48
RSP: 0018:ffffc9000532f4f0 EFLAGS: 00000286
RAX: 0000000000072f44 RBX: ffff8880b8e357a8 RCX: da668651909d9f00
RDX: ffff888027591dc0 RSI: ffffffff8abf1340 RDI: ffffffff8abf1300
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff2117049
R10: fffffbfff2117049 R11: 1ffffffff2117048 R12: 0000000000000cc0
R13: dffffc0000000000 R14: ffffffff8c3d0970 R15: dffffc0000000000
 rcu_read_lock include/linux/rcupdate.h:792 [inline]
 blk_cgroup_congested+0x54/0x220 block/blk-cgroup.c:2012
 __cgroup_throttle_swaprate+0x6d/0x1a0 mm/swapfile.c:3671
 cgroup_throttle_swaprate include/linux/swap.h:662 [inline]
 folio_throttle_swaprate include/linux/swap.h:671 [inline]
 shmem_add_to_page_cache+0x9c1/0x1c00 mm/shmem.c:717
 shmem_get_folio_gfp+0x158b/0x3400 mm/shmem.c:1971
 shmem_fault+0x1be/0x7b0 mm/shmem.c:2156
 __do_fault+0x13b/0x4e0 mm/memory.c:4280
 do_read_fault mm/memory.c:4631 [inline]
 do_fault mm/memory.c:4760 [inline]
 handle_pte_fault mm/memory.c:5031 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x28ca/0x3e70 mm/memory.c:5294
 faultin_page mm/gup.c:1026 [inline]
 __get_user_pages+0x3ff/0xeb0 mm/gup.c:1250
 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607
 __mm_populate+0x248/0x370 mm/gup.c:1721
 mm_populate include/linux/mm.h:2823 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff384b8e929
RSP: 002b:00007ff3849de038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007ff384db6160 RCX: 00007ff384b8e929
RDX: b635773f06ebbeef RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007ff384c10b39 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ff384db6160 R15: 00007ffeb4764558
 </TASK>
rcu: rcu_preempt kthread starved for 10534 jiffies! g11653 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:26496 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:timer_delete_sync+0x181/0x2a0 kernel/time/timer.c:1456
Code: d5 75 10 00 4d 89 ef 48 85 db 49 bd 00 00 00 00 00 fc ff df 75 07 e8 be 75 10 00 eb 06 e8 b7 75 10 00 fb 65 8b 1d 87 0e 92 7e <89> de 81 e6 00 00 0f 00 31 ff e8 00 79 10 00 81 e3 00 00 0f 00 74
RSP: 0018:ffffc90000157b00 EFLAGS: 00000293
RAX: ffffffff817060b9 RBX: 0000000080000000 RCX: ffff88813fe95940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000157bb0 R08: dffffc0000000000 R09: fffffbfff1bfd0b6
R10: fffffbfff1bfd0b6 R11: 1ffffffff1bfd0b5 R12: 1ffff9200002af60
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc90000157be0
 del_timer_sync include/linux/timer.h:198 [inline]
 schedule_timeout+0x164/0x280 kernel/time/timer.c:1966
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:736
Code: 48 89 df e8 47 d4 b8 f7 e9 4c ff ff ff e8 bd 15 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 66 90 0f 00 2d 17 24 4d 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c607d88 EFLAGS: 000002c6
RAX: c557afacb3db2600 RBX: ffffffff8a197f77 RCX: c557afacb3db2600
RDX: 0000000000000001 RSI: ffffffff8a6bffe0 RDI: ffffffff8abf1360
RBP: ffffffff8c607ec0 R08: dffffc0000000000 R09: ffffed10171c6af6
R10: ffffed10171c6af6 R11: 1ffff110171c6af5 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8c6bc680 R15: 1ffffffff1bfd0f6
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3985cb CR3: 000000007caa5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1fc/0x570 kernel/sched/idle.c:303
 cpu_startup_entry+0x3f/0x60 kernel/sched/idle.c:401
 rest_init+0x2dc/0x300 init/main.c:733
 arch_call_rest_init+0xa/0xa init/main.c:893
 start_kernel+0x490/0x539 init/main.c:1140
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/12 14:27 linux-6.1.y 58485ff1a74f 98683f8f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2025/05/20 05:39 linux-6.1.y 325285d9fc86 b84f0537 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2025/03/22 01:04 linux-6.1.y 344a09659766 c6512ef7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2025/03/21 07:31 linux-6.1.y 344a09659766 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2025/03/12 11:58 linux-6.1.y 6ae7ac5c4251 ee70e6db .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2025/01/13 20:48 linux-6.1.y c63962be84ef 249ceea9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
2024/12/17 16:40 linux-6.1.y 52f863f820fd f93b2b55 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in shmem_fault
* Struck through repros no longer work on HEAD.