syzbot


INFO: rcu detected stall in vm_mmap_pgoff

Status: upstream: reported on 2025/07/16 16:43
Reported-by: syzbot+68741367f552e50af6bc@syzkaller.appspotmail.com
First crash: 179d, last: 13d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in vm_mmap_pgoff mm 1 107 3d18h 518d 0/29 upstream: reported on 2024/08/11 07:12
linux-6.1 INFO: rcu detected stall in vm_mmap_pgoff 1 19 46d 568d 0/3 upstream: reported on 2024/06/22 04:29

Sample crash report:
sched: RT throttling activated
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6487/2:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=15345, q=532 ncpus=2)
task:syz.2.137       state:R  running task     stack:25768 pid:6487  ppid:5766   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_is_held_type+0x13e/0x190 kernel/locking/lockdep.c:5830
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90004bef668 EFLAGS: 00000206
RAX: f02ca96c7d324600 RBX: ffff8880278c8000 RCX: f02ca96c7d324600
RDX: ffff8880278c8000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f80
RBP: 0000000000000001 R08: ffff8880278c8000 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000002 R12: 0000000000000001
R13: 0000000000000246 R14: ffffffff8cd2ff20 R15: ffff8880278c8b08
 xa_entry include/linux/xarray.h:1216 [inline]
 xas_find+0x5b1/0xab0 lib/xarray.c:1267
 next_uptodate_folio+0x33/0xae0 mm/filemap.c:3481
 filemap_map_pages+0x228/0x1950 mm/filemap.c:3620
 do_fault_around mm/memory.c:4595 [inline]
 do_read_fault mm/memory.c:4628 [inline]
 do_fault mm/memory.c:4775 [inline]
 do_pte_missing mm/memory.c:3689 [inline]
 handle_pte_fault mm/memory.c:5047 [inline]
 __handle_mm_fault mm/memory.c:5188 [inline]
 handle_mm_fault+0x379b/0x4920 mm/memory.c:5353
 faultin_page mm/gup.c:868 [inline]
 __get_user_pages+0x5ea/0x1470 mm/gup.c:1167
 populate_vma_page_range+0x2b6/0x370 mm/gup.c:1593
 __mm_populate+0x24c/0x380 mm/gup.c:1696
 mm_populate include/linux/mm.h:3383 [inline]
 vm_mmap_pgoff+0x2e7/0x400 mm/util.c:561
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f33f258f749
RSP: 002b:00007f33f3468038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f33f27e6090 RCX: 00007f33f258f749
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f33f2613f91 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33f27e6128 R14: 00007f33f27e6090 R15: 00007ffca33b4d88
 </TASK>
rcu: rcu_preempt kthread starved for 10350 jiffies! g15345 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:26760 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148
Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d 23 bb 40 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56
RSP: 0000:ffffc90000187de0 EFLAGS: 000002c2
RAX: 06a4308b412f7400 RBX: ffffffff8161881b RCX: 06a4308b412f7400
RDX: 0000000000000001 RSI: ffffffff8aaabce0 RDI: ffffffff8afc6f80
RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65
R10: dffffc0000000000 R11: ffffed10171e6d66 R12: ffffffff8e4a2128
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff1100364e780
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c4b279dcc8 CR3: 000000002cefe000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:170 [inline]
 do_idle+0x1eb/0x510 kernel/sched/idle.c:282
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/29 14:12 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
2025/10/19 11:20 linux-6.6.y 0bbbd97a442d 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
2025/09/10 07:49 linux-6.6.y fe9731e10004 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
2025/09/06 11:51 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
2025/08/20 00:50 linux-6.6.y bb9c90ab9c5a 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
2025/07/16 16:43 linux-6.6.y 9247f4e6573a 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in vm_mmap_pgoff
* Struck through repros no longer work on HEAD.