INFO: rcu detected stall in handle_mm_fault (2)

Status: upstream: reported on 2026/09/23 04:22
Reported-by: syzbot+409e7cdb8468360e73c8@syzkaller.appspotmail.com
First crash: 4d10h, last: 4d10h
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in handle_mm_fault (2) arm 1 1 638d 638d 0/29 auto-obsoleted due to no activity on 2025/03/28 01:03
upstream INFO: rcu detected stall in handle_mm_fault fs 1 1 2623d 2622d 0/29 auto-closed as invalid on 2019/10/25 14:11
linux-6.1 INFO: rcu detected stall in handle_mm_fault 1 1 1010d 1010d 0/3 auto-obsoleted due to no activity on 2024/03/30 23:28
linux-5.15 INFO: rcu detected stall in handle_mm_fault (2) missing-backport origin:upstream 1 syz, C error 6 413d 979d 0/3 upstream: reported C repro on 2024/01/22 00:21
linux-5.15 INFO: rcu detected stall in handle_mm_fault 1 1 1087d 1087d 0/3 auto-obsoleted due to no activity on 2024/01/14 02:34
upstream BUG: soft lockup in handle_mm_fault mm 1 153 1852d 1957d 0/29 closed as dup on 2021/05/19 06:00
linux-4.19 BUG: soft lockup in handle_mm_fault 1 1 1329d 1329d 0/1 upstream: reported on 2023/02/05 20:47
upstream BUG: soft lockup in handle_mm_fault (2) arm 1 84 1778d 1847d 0/29 auto-closed as invalid on 2022/02/12 04:15

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8897/1:b..l
	(detected by 0, t=10502 jiffies, g=38773, q=162 ncpus=1)
task:modprobe        state:R  running task     stack:0     pid:8897  ppid:8848   flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0xdb4/0x1a6c kernel/sched/core.c:6563
 preempt_schedule_irq+0x8c/0x1ac kernel/sched/core.c:6875
 arm64_preempt_schedule_irq+0x44/0x54 arch/arm64/kernel/entry-common.c:265
 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline]
 el1_interrupt+0x3c/0x54 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:122
 lock_is_held include/linux/lockdep.h:283 [inline]
 xa_entry include/linux/xarray.h:1199 [inline]
 xas_descend+0xdc/0x40c lib/xarray.c:204
 xas_load lib/xarray.c:242 [inline]
 xas_find+0x198/0x92c lib/xarray.c:1255
 first_map_page mm/filemap.c:3445 [inline]
 filemap_map_pages+0x1d4/0x1284 mm/filemap.c:3472
 do_fault_around mm/memory.c:4598 [inline]
 do_read_fault mm/memory.c:4624 [inline]
 do_fault mm/memory.c:4758 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x1cd0/0x3018 mm/memory.c:5292
 __do_page_fault arch/arm64/mm/fault.c:499 [inline]
 do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583
 do_translation_fault+0x94/0xc8 arch/arm64/mm/fault.c:667
 do_mem_abort+0x70/0x198 arch/arm64/mm/fault.c:804
 el0_ia+0xa4/0x1d0 arch/arm64/kernel/entry-common.c:533
 el0t_64_sync_handler+0xd8/0xf0 arch/arm64/kernel/entry-common.c:661
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
rcu: rcu_preempt kthread starved for 10502 jiffies! g38773 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:0     pid:16    ppid:2      flags:0x00000008
Call trace:
 __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0xdb4/0x1a6c kernel/sched/core.c:6563
 schedule+0xc4/0x170 kernel/sched/core.c:6639
 schedule_timeout+0x194/0x2f4 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x2b0/0x15b8 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xb0/0x300 kernel/rcu/tree.c:1905
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 8892 Comm: syz.4.1304 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : lock_release+0x4c4/0x90c arch/arm64/include/asm/irqflags.h:-1
lr : lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
lr : lock_release+0x48c/0x90c kernel/locking/lockdep.c:5700
sp : ffff8000209d7600
x29: ffff8000209d7640 x28: ffff800015316d00 x27: 0000000000000000
x26: dfff800000000000 x25: 0000000000000000 x24: ffff0000d3642678
x23: 0000000000000001 x22: ffff00019f34cd00 x21: ffffffffffffffff
x20: ffff0000d3641c00 x19: ffff00019f34cd00 x18: 0000000000000000
x17: 0000000000000000 x16: ffff800011bb65f8 x15: 0000ffffc497b7f8
x14: 0000000000000001 x13: 1ffff00002a78071 x12: 000000003552ed0d
x11: ff0080000a97caac x10: 0000000000000000 x9 : 0000000000000080
x8 : 0000000000000000 x7 : ffff8000087f03bc x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : ffff800011d1edc0 x0 : 0000000000000000
Call trace:
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
 lock_release+0x4c4/0x90c kernel/locking/lockdep.c:5701
 __might_fault+0xf0/0x124 mm/memory.c:5850
 restore_sigframe arch/arm64/kernel/signal.c:663 [inline]
 __arm64_sys_rt_sigreturn+0x2e4/0x1f1c arch/arm64/kernel/signal.c:714
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/23 04:22 linux-6.1.y 1a8763b93150 5207b90e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: rcu detected stall in handle_mm_fault
* Struck through repros no longer work on HEAD.