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Tue, 21 Oct 2025 20:00:31 -0700 (PDT) Date: Tue, 21 Oct 2025 20:00:31 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68f848cf.a70a0220.3bf6c6.000e.GAE@google.com> Subject: [syzbot] [mm?] INFO: rcu detected stall in shmem_file_write_iter (3) From: syzbot To: akpm@linux-foundation.org, hannes@cmpxchg.org, jackmanb@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, surenb@google.com, syzkaller-bugs@googlegroups.com, vbabka@suse.cz, ziy@nvidia.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: i4oh9in7nfp7p9ya1h8mjhacsenidgfr X-Rspamd-Queue-Id: A5A0416000A X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761102032-554304 X-HE-Meta: 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 OR13ep+p 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 4s4qzaE3 tb/TtD1GtOmCIrQDjabYTka8FkPT2eOvynQ1olR4SmTXV8ve+8eMpVLLBgIf+SeziatW+0jWoQ2ap/RTBdIKeMomHdp9fE9Ad39eY6qfD9z5Qhrv4JzurhRy7XqD6pJNzqf2JJg1JvFerS6jaPK+Cy1GbHA2XQb4yeegxclR1T7MJ49gzQcjIG1t43+8FhycSfB6vbxUdNS4VOZ5JYcAP5gb9DUctMq6DaA7s6KtQ5DrEP5yRIORX6CmA/n872KfcwkFUwHFSEeSaJLzINXllvdd5hBKfE31AnJjfT1QmIha/vZRm4CUYUfyBGgQ+uf0sb0G+AMA9CSJUOq6jpI9AgOzF36q6AhyNO4edeRVWOP4cBzbSgqQlsc+QJne3PeLfVDNwamzTMqlHyVbfnJLHNzdyqa2jfNPLtF+ffNs0Q3nPIRCFnsuDSXdmvliia6wyNwM6l1EB7eeiI9nrC+N2+knFkbytg6NP9bGImOWE+/cBtKLuHRnKLgvRa6XzLyY X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello, syzbot found the following issue on: HEAD commit: f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=123fede2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=9ad7b090a18654a7 dashboard link: https://syzkaller.appspot.com/bug?extid=f172d48953db0cf91855 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/37fd0378c30b/disk-f406055c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f26ca5f11670/vmlinux-f406055c.xz kernel image: https://storage.googleapis.com/syzbot-assets/145dd878db42/bzImage-f406055c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f172d48953db0cf91855@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9351/3:b..l P5822/1:b..l P9346/1:b..l rcu: (detected by 1, t=10502 jiffies, g=30189, q=343 ncpus=2) task:syz.4.823 state:R running task stack:25608 pid:9346 tgid:9345 ppid:5831 task_flags:0x400040 flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7256 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5872 Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 fb bc f3 10 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc900188bef98 EFLAGS: 00000206 RAX: 8c7b37c73e5bc200 RBX: 0000000000000000 RCX: 8c7b37c73e5bc200 RDX: 0000000000000000 RSI: ffffffff8d9d1f00 RDI: ffffffff8bc07de0 RBP: ffffffff8173cd25 R08: 0000000000000000 R09: ffffffff8173cd25 R10: dffffc0000000000 R11: ffffffff81ac6cd0 R12: 0000000000000002 R13: ffffffff8e13d2e0 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] class_rcu_constructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf5/0x1f0 mm/page_owner.c:156 __set_page_owner+0x8d/0x4a0 mm/page_owner.c:329 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850 prep_new_page mm/page_alloc.c:1858 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2435 shmem_alloc_folio mm/shmem.c:1871 [inline] shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1910 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2533 shmem_get_folio mm/shmem.c:2639 [inline] shmem_write_begin+0xf7/0x2b0 mm/shmem.c:3289 generic_perform_write+0x2c5/0x900 mm/filemap.c:4242 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3464 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f32a238da7f RSP: 002b:00007f32a31d6df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f32a238da7f RDX: 0000000001000000 RSI: 00007f3298000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000004431 R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003 R13: 00007f32a31d6ef0 R14: 00007f32a31d6eb0 R15: 00007f3298000000 task:syz-executor state:R running task stack:20904 pid:5822 tgid:5822 ppid:5817 task_flags:0x400140 flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] copy_pte_range mm/memory.c:1329 [inline] copy_pmd_range+0x7630/0x7f00 mm/memory.c:1389 copy_pud_range mm/memory.c:1426 [inline] copy_p4d_range mm/memory.c:1450 [inline] copy_page_range+0xc14/0x1270 mm/memory.c:1538 dup_mmap+0xf4c/0x1b10 mm/mmap.c:1834 dup_mm kernel/fork.c:1489 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1541 copy_process+0x1706/0x3c00 kernel/fork.c:2181 kernel_clone+0x21e/0x840 kernel/fork.c:2609 __do_sys_clone kernel/fork.c:2750 [inline] __se_sys_clone kernel/fork.c:2734 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2734 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f07d7f85713 RSP: 002b:00007ffca17e20f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f07d7f85713 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000555592a5e7d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000495e1 R15: 00007ffca17e2290 task:syz.0.826 state:R running task stack:25624 pid:9351 tgid:9348 ppid:5832 task_flags:0x400040 flags:0x00080001 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7113 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7137 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] filemap_map_pages+0x1621/0x1c60 mm/filemap.c:3858 do_fault_around mm/memory.c:5656 [inline] do_read_fault mm/memory.c:5689 [inline] do_fault mm/memory.c:5832 [inline] do_pte_missing mm/memory.c:4361 [inline] handle_pte_fault mm/memory.c:6177 [inline] __handle_mm_fault+0x347e/0x5400 mm/memory.c:6318 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6487 faultin_page mm/gup.c:1126 [inline] __get_user_pages+0x165c/0x2a00 mm/gup.c:1428 populate_vma_page_range+0x29f/0x3a0 mm/gup.c:1860 __mm_populate+0x24c/0x380 mm/gup.c:1963 mm_populate include/linux/mm.h:3471 [inline] vm_mmap_pgoff+0x387/0x4d0 mm/util.c:586 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faa11f8efc9 RSP: 002b:00007faa12e69038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007faa121e6090 RCX: 00007faa11f8efc9 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007faa12011f91 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 00007faa121e6128 R14: 00007faa121e6090 R15: 00007ffc1db85d48 rcu: rcu_preempt kthread starved for 10330 jiffies! g30189 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:27288 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 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 10/02/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: 5e c3 c3 f5 cc cc cc 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 33 b1 1b 00 f3 0f 1e fa fb f4 33 c3 c3 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000197de0 EFLAGS: 000002c6 RAX: 82b01eb804bc8c00 RBX: ffffffff8196bc07 RCX: 82b01eb804bc8c00 RDX: 0000000000000001 RSI: ffffffff8d7e8bf1 RDI: ffffffff8bc07de0 RBP: ffffc90000197f10 R08: ffff8880b8732fdb R09: 1ffff110170e65fb R10: dffffc0000000000 R11: ffffed10170e65fc R12: ffffffff8f9e1e70 R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110038d5b58 FS: 0000000000000000(0000) GS:ffff888125e0b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6547b7915e CR3: 00000000306ab000 CR4: 0000000000350ef0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:190 [inline] do_idle+0x1e7/0x510 kernel/sched/idle.c:330 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x147 --- This report is generated by a bot. 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