INFO: task kworker/u4:1:144 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:1 state:D stack:21728 pid: 144 ppid: 2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_bit_io include/linux/wait_bit.h:101 [inline] do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251 __ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235 ext4_mb_mark_diskspace_used+0x1c9/0x14e0 fs/ext4/mballoc.c:3871 ext4_mb_new_blocks+0x11ab/0x47c0 fs/ext4/mballoc.c:5806 ext4_ext_map_blocks+0x17d1/0x63d0 fs/ext4/extents.c:4372 ext4_map_blocks+0x97f/0x1a50 fs/ext4/inode.c:675 mpage_map_one_extent fs/ext4/inode.c:2410 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2463 [inline] ext4_writepages+0x124a/0x2d40 fs/ext4/inode.c:2831 do_writepages+0x493/0x700 mm/page-writeback.c:2386 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657 writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011 wb_writeback+0x45e/0xbc0 fs/fs-writeback.c:2116 wb_check_old_data_flush fs/fs-writeback.c:2216 [inline] wb_do_writeback fs/fs-writeback.c:2269 [inline] wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 INFO: task jbd2/sda1-8:3521 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:jbd2/sda1-8 state:D stack:25776 pid: 3521 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_buffer include/linux/buffer_head.h:390 [inline] jbd2_journal_commit_transaction+0x2f0b/0x5c30 fs/jbd2/commit.c:848 kjournald2+0x45a/0x900 fs/jbd2/journal.c:213 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 INFO: task syz-executor:4174 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:22864 pid: 4174 ppid: 4173 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_bit_io include/linux/wait_bit.h:101 [inline] do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251 __ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235 ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866 __ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 wp_page_shared+0x163/0x6c0 mm/memory.c:3259 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7fdb0c391123 RSP: 002b:00007fff55419f30 EFLAGS: 00010216 RAX: 00007fdb07120f74 RBX: 00007fff5541a060 RCX: 0000000000000000 RDX: 00007fdb07120f70 RSI: 0000000000000008 RDI: 00007fff5541a060 RBP: 00000000000003e6 R08: 0000000000000000 R09: 0000000000000000 R10: 00007fff5541a040 R11: 0000000000000000 R12: 0000000000000000 R13: 000000000000008c R14: ffffffffffffff74 R15: 0000000000000000 INFO: task syz.3.588:6354 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.3.588 state:D stack:27696 pid: 6354 ppid: 4187 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_bit_io include/linux/wait_bit.h:101 [inline] do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251 __ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235 ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866 __ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 do_shared_fault mm/memory.c:4328 [inline] do_fault mm/memory.c:4396 [inline] handle_pte_fault mm/memory.c:4650 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1e47/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7f6dafbcf740 RSP: 002b:00007ffd6e7ee520 EFLAGS: 00010202 RAX: 0000001b32924000 RBX: 0000000000000000 RCX: 00000000003ffde8 RDX: 0000001b32923ffc RSI: 00000000003ffde8 RDI: 00007f6db0ab2700 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f6daff6f000 R10: 00007f6db0ab2700 R11: 0000000000000000 R12: 0000000000000000 R13: 000000000000907a R14: ffffffff819d3f44 R15: 00007f6db0ab2720 INFO: task syz.5.590:6358 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.5.590 state:D stack:27536 pid: 6358 ppid: 4837 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_bit_io include/linux/wait_bit.h:101 [inline] do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251 __ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235 ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866 __ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 wp_page_shared+0x163/0x6c0 mm/memory.c:3259 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7f3035a30740 RSP: 002b:00007ffc7b541950 EFLAGS: 00010206 RAX: 0000001b32d23f8c RBX: ffffffffffffff8c RCX: ffffffff819d3802 RDX: 0000001b32d23f88 RSI: 0000000000000004 RDI: 00007f3036913720 RBP: 0000000000000000 R08: 00007f3035dce000 R09: 00007f3035dd0000 R10: 00000000819d3806 R11: 0000000000000005 R12: 0000000000000000 R13: 00000000000062bb R14: ffffffff819d3f44 R15: 00007f3036913720 INFO: task syz.4.591:6360 blocked for more than 145 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.4.591 state:D stack:27440 pid: 6360 ppid: 4195 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 io_schedule+0x7c/0xd0 kernel/sched/core.c:8503 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209 __wait_on_bit kernel/sched/wait_bit.c:49 [inline] out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64 wait_on_bit_io include/linux/wait_bit.h:101 [inline] do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251 __ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235 ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866 __ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922 wp_page_shared+0x163/0x6c0 mm/memory.c:3259 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7ff8c0417806 RSP: 002b:00007ffe1e6df8f0 EFLAGS: 00010202 RAX: 0000001b32a23f90 RBX: ffffffff812c42d5 RCX: 0000000000000004 RDX: 0000001b32624220 RSI: 0000000000000004 RDI: 00007ff8c12fa720 RBP: 0000000000000000 R08: 00007ff8c07b5000 R09: 00007ff8c07b7000 R10: 00000000812c42d9 R11: 0000000000000005 R12: 00007ff8c07cb038 R13: 0000000000000ca4 R14: ffffffff812c4b2f R15: 00007ff8c12fa720 Showing all locks held in the system: 1 lock held by khungtaskd/27: #0: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 6 locks held by kworker/u4:1/144: #0: ffff888141f80138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1 #1: ffffc9000168fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285 #2: ffff88814cec20e0 (&type->s_umount_key#32){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418 #3: ffff88814cec4c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x213/0x2d40 fs/ext4/inode.c:2691 #4: ffff88814cec6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 #5: ffff8880747b5238 (&ei->i_data_sem){++++}-{3:3}, at: ext4_map_blocks+0x8c4/0x1a50 fs/ext4/inode.c:668 4 locks held by kworker/0:2/1106: #0: ffff8880b903a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:475 #1: ffff8880b9027888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4c3/0x810 kernel/sched/psi.c:882 #2: ffff8880b90280d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:946 #3: ffff8880789e28e0 (&nsim_trap_data->trap_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #3: ffff8880789e28e0 (&nsim_trap_data->trap_lock){+.+.}-{2:2}, at: nsim_dev_trap_report drivers/net/netdevsim/dev.c:707 [inline] #3: ffff8880789e28e0 (&nsim_trap_data->trap_lock){+.+.}-{2:2}, at: nsim_dev_trap_report_work+0x198/0xab0 drivers/net/netdevsim/dev.c:762 2 locks held by getty/3944: #0: ffff88802beaf098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158 3 locks held by syz-executor/4174: #0: ffff888079dc6a28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff888079dc6a28 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296 #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194 #2: ffff88814cec6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 2 locks held by kworker/u4:6/4303: #0: ffff8880b913a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:475 #1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x517/0x810 kernel/sched/psi.c:891 2 locks held by syz-executor/5522: #0: ffff888075e800e0 (&type->s_umount_key#105){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365 #1: ffffffff8c571728 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x4f/0x1a0 fs/nfsd/nfssvc.c:634 3 locks held by syz.3.588/6354: #0: ffff88802c6c1628 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff88802c6c1628 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296 #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194 #2: ffff88814cec6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 3 locks held by syz.5.590/6358: #0: ffff888022f6dc28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff888022f6dc28 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296 #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194 #2: ffff88814cec6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 3 locks held by syz.4.591/6360: #0: ffff88802c6c2428 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline] #0: ffff88802c6c2428 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296 #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline] #1: ffff88814cec2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194 #2: ffff88814cec6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline] watchdog+0xe1b/0xe60 kernel/hung_task.c:369 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 31 Comm: kcompactd1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:fill_contig_page_info mm/vmstat.c:1078 [inline] RIP: 0010:extfrag_for_order+0xe5/0x380 mm/vmstat.c:1126 Code: 48 0f 42 c8 48 89 4c 24 38 49 8d be d8 02 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 74 05 e8 b2 29 16 00 49 8b 86 d8 02 00 00 <4c> 8d 3c c3 b1 03 44 28 e1 48 d3 e0 31 c9 83 fd 04 48 0f 42 c8 48 RSP: 0018:ffffc90000e6fab8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88823fff82d8 RBP: 0000000000000009 R08: ffff88823fffcc4b R09: 1ffff11047fff989 R10: dffffc0000000000 R11: ffffed1047fff98a R12: 0000000000000009 R13: dffffc0000000000 R14: ffff88823fff8000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055bfb8bb2660 CR3: 000000007e6a9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fragmentation_score_zone mm/compaction.c:1990 [inline] fragmentation_score_zone_weighted mm/compaction.c:2007 [inline] fragmentation_score_node mm/compaction.c:2027 [inline] should_proactive_compact_node mm/compaction.c:2054 [inline] kcompactd+0xcde/0x1ff0 mm/compaction.c:2979 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287