INFO: task hung in mpage_prepare_extent_to_map

Status: upstream: reported on 2026/10/17 01:46
Reported-by: syzbot+3facec67693e1944e32d@syzkaller.appspotmail.com
First crash: 1d09h, last: 1d09h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in mpage_prepare_extent_to_map 1 syz done 18606 2538d 2546d 14/29 fixed on 2019/11/29 15:48
linux-6.6 INFO: task hung in mpage_prepare_extent_to_map 1 2 8d15h 61d 0/2 upstream: reported on 2026/08/18 02:27
upstream INFO: task hung in mpage_prepare_extent_to_map (2) ext4 1 4 695d 697d 0/29 auto-obsoleted due to no activity on 2025/02/20 07:58
upstream INFO: task hung in mpage_prepare_extent_to_map (3) ext4 mm 1 3 551d 579d 0/29 auto-obsoleted due to no activity on 2025/07/14 01:35
linux-5.15 INFO: task hung in mpage_prepare_extent_to_map 1 1 74d 74d 0/3 upstream: reported on 2026/08/04 19:48

Sample crash report:
INFO: task kworker/u4:4:76 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:4    state:D stack:21936 pid:76    ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
 folio_wait_bit_common+0x877/0xfa0 mm/filemap.c:1324
 folio_wait_writeback+0xe3/0x1f0 mm/page-writeback.c:3058
 mpage_prepare_extent_to_map+0x715/0x1690 fs/ext4/inode.c:2657
 ext4_writepages+0x9da/0x2e70 fs/ext4/inode.c:2811
 do_writepages+0x3c6/0x640 mm/page-writeback.c:2491
 __writeback_single_inode+0x153/0x1170 fs/fs-writeback.c:1688
 writeback_sb_inodes+0xad5/0x17f0 fs/fs-writeback.c:1979
 wb_writeback+0x470/0xd40 fs/fs-writeback.c:2153
 wb_do_writeback fs/fs-writeback.c:2296 [inline]
 wb_workfn+0x423/0xee0 fs/fs-writeback.c:2336
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: task jbd2/sda1-8:3602 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:25872 pid:3602  ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
 __wait_on_bit+0x9b/0x2c0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x138/0x190 kernel/sched/wait_bit.c:64
 wait_on_buffer include/linux/buffer_head.h:385 [inline]
 jbd2_journal_commit_transaction+0x2f0f/0x5f30 fs/jbd2/commit.c:849
 kjournald2+0x40b/0x800 fs/jbd2/journal.c:210
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: task syz-executor:4260 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22992 pid:4260  ppid:4259   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
 __wait_on_bit+0x9b/0x2c0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x138/0x190 kernel/sched/wait_bit.c:64
 wait_on_bit_io include/linux/wait_bit.h:101 [inline]
 do_get_write_access+0x605/0xf20 fs/jbd2/transaction.c:1115
 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
 __ext4_journal_get_write_access+0x24b/0x6e0 fs/ext4/ext4_jbd2.c:235
 ext4_reserve_inode_write+0x201/0x290 fs/ext4/inode.c:5945
 __ext4_mark_inode_dirty+0x161/0x7b0 fs/ext4/inode.c:6129
 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6166
 __mark_inode_dirty+0x2e7/0xe80 fs/fs-writeback.c:2515
 generic_update_time fs/inode.c:1946 [inline]
 inode_update_time fs/inode.c:1959 [inline]
 __file_update_time+0x21d/0x240 fs/inode.c:2147
 file_update_time+0x2f3/0x370 fs/inode.c:2178
 ext4_page_mkwrite+0x1a9/0x10d0 fs/ext4/inode.c:6284
 do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3009
 wp_page_shared+0x167/0x370 mm/memory.c:3358
 handle_pte_fault mm/memory.c:5047 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x1b1b/0x3d40 mm/memory.c:5292
 do_user_addr_fault+0x58e/0xb20 arch/x86/mm/fault.c:1338
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7ff4d427cae2
RSP: 002b:00007ffd6e3bde80 EFLAGS: 00010202
RAX: 00007ff4d2078000 RBX: 000055556d84d480 RCX: 0000000000000006
RDX: 0000000000001829 RSI: 000055556d8ba878 RDI: 0000000000000040
RBP: 00007ffd6e3be380 R08: 000055556d8ba8f8 R09: 000000000000008b
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd6e3be1c0
R13: 00007ffd6e3bdfb0 R14: 585858582e7a7973 R15: 00007ffd6e3bdf00
 </TASK>
INFO: task syz.2.500:5871 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.500       state:D stack:27664 pid:5871  ppid:4275   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 wb_wait_for_completion+0x16f/0x290 fs/fs-writeback.c:191
 sync_inodes_sb+0x1c5/0xa10 fs/fs-writeback.c:2822
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 ksys_sync_helper+0x13/0xa0 kernel/power/main.c:63
 enter_state kernel/power/suspend.c:583 [inline]
 pm_suspend+0x1b4/0x9a0 kernel/power/suspend.c:626
 state_store+0x202/0x290 kernel/power/main.c:639
 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2271 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc0c619e559
RSP: 002b:00007fc0c6f9e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc0c6425fa0 RCX: 00007fc0c619e559
RDX: 0000000000000006 RSI: 0000200000000440 RDI: 0000000000000003
RBP: 00007fc0c6235ab8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc0c6426038 R14: 00007fc0c6425fa0 R15: 00007fff9dc9df68
 </TASK>
INFO: task syz.0.524:5956 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.524       state:D stack:26256 pid:5956  ppid:4272   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
 __wait_on_bit+0x9b/0x2c0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x138/0x190 kernel/sched/wait_bit.c:64
 wait_on_bit_io include/linux/wait_bit.h:101 [inline]
 do_get_write_access+0x605/0xf20 fs/jbd2/transaction.c:1115
 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
 __ext4_journal_get_write_access+0x24b/0x6e0 fs/ext4/ext4_jbd2.c:235
 ext4_reserve_inode_write+0x201/0x290 fs/ext4/inode.c:5945
 __ext4_mark_inode_dirty+0x161/0x7b0 fs/ext4/inode.c:6129
 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6166
 __mark_inode_dirty+0x2e7/0xe80 fs/fs-writeback.c:2515
 generic_update_time fs/inode.c:1946 [inline]
 inode_update_time fs/inode.c:1959 [inline]
 __file_update_time+0x21d/0x240 fs/inode.c:2147
 file_update_time+0x2f3/0x370 fs/inode.c:2178
 ext4_page_mkwrite+0x1a9/0x10d0 fs/ext4/inode.c:6284
 do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3009
 do_shared_fault mm/memory.c:4694 [inline]
 do_fault mm/memory.c:4762 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x199c/0x3d40 mm/memory.c:5292
 do_user_addr_fault+0x58e/0xb20 arch/x86/mm/fault.c:1338
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fc12ae72c09
RSP: 002b:00007ffd21fe81e0 EFLAGS: 00010202
RAX: 0000001b2fb24000 RBX: 0000000000000000 RCX: 00000000003ffde8
RDX: 0000001b2fb23ffc RSI: 00000000003ffde8 RDI: 00007fc12bd55700
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007fc12b212000
R10: 00007fc12bd55700 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000008e68 R14: ffffffff812f8b30 R15: 00007fc12bd55720
 </TASK>
INFO: task syz.5.528:5975 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.528       state:D stack:26256 pid:5975  ppid:4780   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
 bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
 __wait_on_bit+0x9b/0x2c0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x138/0x190 kernel/sched/wait_bit.c:64
 wait_on_bit_io include/linux/wait_bit.h:101 [inline]
 do_get_write_access+0x605/0xf20 fs/jbd2/transaction.c:1115
 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
 __ext4_journal_get_write_access+0x24b/0x6e0 fs/ext4/ext4_jbd2.c:235
 ext4_reserve_inode_write+0x201/0x290 fs/ext4/inode.c:5945
 __ext4_mark_inode_dirty+0x161/0x7b0 fs/ext4/inode.c:6129
 ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6166
 __mark_inode_dirty+0x2e7/0xe80 fs/fs-writeback.c:2515
 generic_update_time fs/inode.c:1946 [inline]
 inode_update_time fs/inode.c:1959 [inline]
 __file_update_time+0x21d/0x240 fs/inode.c:2147
 file_update_time+0x2f3/0x370 fs/inode.c:2178
 ext4_page_mkwrite+0x1a9/0x10d0 fs/ext4/inode.c:6284
 do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3009
 do_shared_fault mm/memory.c:4694 [inline]
 do_fault mm/memory.c:4762 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x199c/0x3d40 mm/memory.c:5292
 do_user_addr_fault+0x58e/0xb20 arch/x86/mm/fault.c:1338
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f709a272c09
RSP: 002b:00007ffec2da27e0 EFLAGS: 00010202
RAX: 0000001b2e524000 RBX: 0000000000000000 RCX: 00000000003ffde8
RDX: 0000001b2e523ffc RSI: 00000000003ffde8 RDI: 00007f709b155700
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f709a612000
R10: 00007f709b155700 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000bf4 R14: ffffffff812f8a4c R15: 00007f709b155720
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d92e230 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d92ea50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669
3 locks held by kworker/u4:4/76:
 #0: ffff88814369c938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90001597d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff88814dd6ac18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x213/0x2e70 fs/ext4/inode.c:2717
2 locks held by getty/4029:
 #0: ffff888031254098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by syz-executor/4260:
 #0: ffff88807a59d3d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff88807a59d3d8 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff88807a59d3d8 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1897 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:2001 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6283
 #2: ffff88814dd6c990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
7 locks held by syz.2.500/5871:
 #0: ffff888029a16ae8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
 #1: ffff888078080460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
 #2: ffff8880288b1888 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1d8/0x520 fs/kernfs/file.c:343
 #3: ffff88801a279748 (kn->active#82){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #3: ffff88801a279748 (kn->active#82){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x520 fs/kernfs/file.c:344
 #4: ffffffff8d7e2aa8 (system_transition_mutex){+.+.}-{3:3}, at: enter_state kernel/power/suspend.c:575 [inline]
 #4: ffffffff8d7e2aa8 (system_transition_mutex){+.+.}-{3:3}, at: pm_suspend+0x11c/0x9a0 kernel/power/suspend.c:626
 #5: ffff88814dd680e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #6: ffff888028714820 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #6: ffff888028714820 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2820
3 locks held by syz.0.524/5956:
 #0: ffff88807d35f1d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff88807d35f1d8 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff88807d35f1d8 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1897 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:2001 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6283
 #2: ffff88814dd6c990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
3 locks held by syz.5.528/5975:
 #0: ffff888072f508d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff888072f508d8 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff888072f508d8 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1897 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:2001 [inline]
 #1: ffff88814dd68558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6283
 #2: ffff88814dd6c990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9 Comm: kworker/u4:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:mark_held_locks kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__trace_hardirqs_on_caller kernel/locking/lockdep.c:4320 [inline]
RIP: 0010:lockdep_hardirqs_on_prepare+0x23e/0x7c0 kernel/locking/lockdep.c:4387
Code: 20 a9 00 00 04 00 74 34 25 00 00 03 00 83 f8 01 ba 03 00 00 00 83 da 00 48 89 df 4c 89 fe e8 b9 f6 00 00 48 8d b3 d8 0a 00 00 <48> ba 00 00 00 00 00 fc ff df 85 c0 0f 84 ec 01 00 00 41 0f b6 04
RSP: 0018:ffffc900000e7960 EFLAGS: 00000086
RAX: 0000000000000001 RBX: ffff88813fe60000 RCX: ffffffff8164beb4
RDX: 0000000000000000 RSI: ffff88813fe60ad8 RDI: ffffffff91934320
RBP: ffffc900000e7a08 R08: ffffffff91934327 R09: 1ffffffff2326864
R10: dffffc0000000000 R11: fffffbfff2326865 R12: ffff88813fe60b50
R13: 0000000000000002 R14: 1ffff11027fcc15b R15: ffff88813fe60b30
FS:  0000000000000000(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005632412f6660 CR3: 000000007cc5f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 trace_hardirqs_on+0x34/0x40 kernel/trace/trace_preemptirq.c:49
 ___slab_alloc+0x369/0x1240 mm/slub.c:3069
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 kmem_cache_alloc_node+0x134/0x310 mm/slub.c:3404
 __alloc_skb+0xf9/0x7d0 net/core/skbuff.c:505
 alloc_skb include/linux/skbuff.h:1303 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x24f/0xa80 drivers/net/netdevsim/dev.c:851
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 01:45 linux-6.1.y 79807e970724 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in mpage_prepare_extent_to_map
* Struck through repros no longer work on HEAD.