Re: [syzbot] [mm?] INFO: task hung in write_cache_pages (2)
From: Huang, Ying
Date: Thu Mar 02 2023 - 18:44:36 EST
Yang Shi <shy828301@xxxxxxxxx> writes:
> On Wed, Mar 1, 2023 at 4:36 PM syzbot
> <syzbot+0adf31ecbba886ab504f@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: 489fa31ea873 Merge branch 'work.misc' of git://git.kernel...
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1034fef8c80000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=cbfa7a73c540248d
>> dashboard link: https://syzkaller.appspot.com/bug?extid=0adf31ecbba886ab504f
>> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16dc6960c80000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16f39d50c80000
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/8121ff3f8044/disk-489fa31e.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/ba8296ba1bf7/vmlinux-489fa31e.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/6459f50e23f3/bzImage-489fa31e.xz
>> mounted in repro: https://storage.googleapis.com/syzbot-assets/845f6538108c/mount_1.gz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+0adf31ecbba886ab504f@xxxxxxxxxxxxxxxxxxxxxxxxx
>>
>> INFO: task kworker/u4:0:9 blocked for more than 143 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:kworker/u4:0 state:D stack:21720 pid:9 ppid:2 flags:0x00004000
>> Workqueue: writeback wb_workfn (flush-7:0)
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_lock include/linux/pagemap.h:952 [inline]
>> write_cache_pages+0x58f/0x1450 mm/page-writeback.c:2440
>> mpage_writepages+0x107/0x1d0 fs/mpage.c:653
>> do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
>> __writeback_single_inode+0x1c4/0x15e0 fs/fs-writeback.c:1600
>> writeback_sb_inodes+0x92c/0x1360 fs/fs-writeback.c:1891
>> __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:1962
>> wb_writeback+0x51c/0x1080 fs/fs-writeback.c:2067
>> wb_check_background_flush fs/fs-writeback.c:2133 [inline]
>> wb_do_writeback fs/fs-writeback.c:2221 [inline]
>> wb_workfn+0xd80/0x1100 fs/fs-writeback.c:2248
>> process_one_work+0x915/0x13a0 kernel/workqueue.c:2390
>> worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
>> kthread+0x270/0x300 kernel/kthread.c:376
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>> </TASK>
>> INFO: task kworker/u4:2:41 blocked for more than 143 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:kworker/u4:2 state:D stack:20480 pid:41 ppid:2 flags:0x00004000
>> Workqueue: writeback wb_workfn (flush-7:5)
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_lock include/linux/pagemap.h:952 [inline]
>> write_cache_pages+0x58f/0x1450 mm/page-writeback.c:2440
>> mpage_writepages+0x107/0x1d0 fs/mpage.c:653
>> do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
>> __writeback_single_inode+0x1c4/0x15e0 fs/fs-writeback.c:1600
>> writeback_sb_inodes+0x92c/0x1360 fs/fs-writeback.c:1891
>> __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:1962
>> wb_writeback+0x51c/0x1080 fs/fs-writeback.c:2067
>> wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
>> wb_do_writeback fs/fs-writeback.c:2220 [inline]
>> wb_workfn+0xccb/0x1100 fs/fs-writeback.c:2248
>> process_one_work+0x915/0x13a0 kernel/workqueue.c:2390
>> worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
>> kthread+0x270/0x300 kernel/kthread.c:376
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>> </TASK>
>> INFO: task kworker/u4:4:75 blocked for more than 144 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:kworker/u4:4 state:D stack:25088 pid:75 ppid:2 flags:0x00004000
>> Workqueue: writeback wb_workfn (flush-7:1)
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_lock include/linux/pagemap.h:952 [inline]
>> write_cache_pages+0x58f/0x1450 mm/page-writeback.c:2440
>> mpage_writepages+0x107/0x1d0 fs/mpage.c:653
>> do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
>> __writeback_single_inode+0x1c4/0x15e0 fs/fs-writeback.c:1600
>> writeback_sb_inodes+0x92c/0x1360 fs/fs-writeback.c:1891
>> __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:1962
>> wb_writeback+0x51c/0x1080 fs/fs-writeback.c:2067
>> wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
>> wb_do_writeback fs/fs-writeback.c:2220 [inline]
>> wb_workfn+0xccb/0x1100 fs/fs-writeback.c:2248
>> process_one_work+0x915/0x13a0 kernel/workqueue.c:2390
>> worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
>> kthread+0x270/0x300 kernel/kthread.c:376
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>> </TASK>
>> INFO: task syz-executor359:5222 blocked for more than 144 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:26576 pid:5222 ppid:5113 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
>> rwsem_down_read_slowpath+0x5f4/0x950 kernel/locking/rwsem.c:1086
>> __down_read_common+0x61/0x2c0 kernel/locking/rwsem.c:1250
>> mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
>> RIP: 0033:0x7fd6f371b888
>> RSP: 002b:00007ffd6fdf2398 EFLAGS: 00010206
>> RAX: 00007fd6f374ebd0 RBX: 00007fd6f374d1a8 RCX: 0000000000000001
>> RDX: 00007fd6f3688d30 RSI: 0000000000000000 RDI: 00007fd6f374ebd0
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000010
>> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>> R13: 0000000000000001 R14: 00007fd6f37543e0 R15: 0000000000000001
>> </TASK>
>> INFO: task syz-executor359:5223 blocked for more than 144 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:24840 pid:5223 ppid:5113 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_lock include/linux/pagemap.h:952 [inline]
>> write_cache_pages+0x58f/0x1450 mm/page-writeback.c:2440
>> mpage_writepages+0x107/0x1d0 fs/mpage.c:653
>> do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
>> filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:390
>> __filemap_fdatawrite_range mm/filemap.c:423 [inline]
>> file_write_and_wait_range+0x20f/0x300 mm/filemap.c:781
>> __generic_file_fsync+0x72/0x190 fs/libfs.c:1132
>> fat_file_fsync+0x7e/0x190 fs/fat/file.c:191
>> generic_write_sync include/linux/fs.h:2452 [inline]
>> generic_file_write_iter+0x2a1/0x310 mm/filemap.c:4090
>> call_write_iter include/linux/fs.h:1851 [inline]
>> new_sync_write fs/read_write.c:491 [inline]
>> vfs_write+0x7b2/0xbb0 fs/read_write.c:584
>> ksys_write+0x1a0/0x2c0 fs/read_write.c:637
>> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
>> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fd6f36ca719
>> RSP: 002b:00007fd6f36762f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 00007fd6f374f7a0 RCX: 00007fd6f36ca719
>> RDX: 000000000208e24b RSI: 0000000020000080 RDI: 0000000000000004
>> RBP: 00007fd6f371c604 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd6f371c0e0
>> R13: 0000000020000a80 R14: 0030656c69662f2e R15: 00007fd6f374f7a8
>> </TASK>
>> INFO: task syz-executor359:5229 blocked for more than 144 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:26504 pid:5229 ppid:5113 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_wait_writeback+0xec/0x1f0 mm/page-writeback.c:3127
>> migrate_folio_unmap mm/migrate.c:1192 [inline]
>> migrate_pages_batch mm/migrate.c:1685 [inline]
>> migrate_pages+0x2d50/0x6610 mm/migrate.c:1973
>
> The migration has locked the page, but is waiting for writeback. The
> writeback is waiting for the page lock...
>
> I recalled Huge reported the same bug. There is a patch to solve it,
> but may be not shown in linus's tree yet. And It seems like the
> reproducer is dirtying some files on loop device and calling mbind at
> the same time. This does match the reproducer mentioned by Hugh.
Yes. We have fixed a bug report similar. The fix patchset is as
follows,
https://lore.kernel.org/linux-mm/20230224141145.96814-1-ying.huang@xxxxxxxxx/
It will take some time for it to land in Linus's tree.
Best Regards,
Huang, Ying
>> do_mbind mm/mempolicy.c:1338 [inline]
>> kernel_mbind mm/mempolicy.c:1485 [inline]
>> __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> __se_sys_mbind+0x75a/0x9c0 mm/mempolicy.c:1555
>> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
>> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fd6f36ca719
>> RSP: 002b:00007fd6eb3552e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
>> RAX: ffffffffffffffda RBX: 00007fd6f374f7b0 RCX: 00007fd6f36ca719
>> RDX: 0000000000000000 RSI: 0000000000800000 RDI: 0000000020001000
>> RBP: 00007fd6f371c604 R08: 0000000000000000 R09: 0000000000000002
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd6f371c0e0
>> R13: 0000000020000a80 R14: 0030656c69662f2e R15: 00007fd6f374f7b8
>> </TASK>
>> INFO: task syz-executor359:5296 blocked for more than 145 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:27008 pid:5296 ppid:5112 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
>> rwsem_down_read_slowpath+0x5f4/0x950 kernel/locking/rwsem.c:1086
>> __down_read_common+0x61/0x2c0 kernel/locking/rwsem.c:1250
>> mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
>> RIP: 0033:0x7fd6f371b888
>> RSP: 002b:00007ffd6fdf2398 EFLAGS: 00010206
>> RAX: 00007fd6f374ebd0 RBX: 00007fd6f374d1a8 RCX: 0000000000000001
>> RDX: 00007fd6f3688d30 RSI: 0000000000000000 RDI: 00007fd6f374ebd0
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000010
>> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>> R13: 0000000000000001 R14: 00007fd6f37543e0 R15: 0000000000000001
>> </TASK>
>> INFO: task syz-executor359:5298 blocked for more than 145 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:24840 pid:5298 ppid:5112 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_lock include/linux/pagemap.h:952 [inline]
>> write_cache_pages+0x58f/0x1450 mm/page-writeback.c:2440
>> mpage_writepages+0x107/0x1d0 fs/mpage.c:653
>> do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
>> filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:390
>> __filemap_fdatawrite_range mm/filemap.c:423 [inline]
>> file_write_and_wait_range+0x20f/0x300 mm/filemap.c:781
>> __generic_file_fsync+0x72/0x190 fs/libfs.c:1132
>> fat_file_fsync+0x7e/0x190 fs/fat/file.c:191
>> generic_write_sync include/linux/fs.h:2452 [inline]
>> generic_file_write_iter+0x2a1/0x310 mm/filemap.c:4090
>> call_write_iter include/linux/fs.h:1851 [inline]
>> new_sync_write fs/read_write.c:491 [inline]
>> vfs_write+0x7b2/0xbb0 fs/read_write.c:584
>> ksys_write+0x1a0/0x2c0 fs/read_write.c:637
>> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
>> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fd6f36ca719
>> RSP: 002b:00007fd6f36762f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 00007fd6f374f7a0 RCX: 00007fd6f36ca719
>> RDX: 000000000208e24b RSI: 0000000020000080 RDI: 0000000000000004
>> RBP: 00007fd6f371c604 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd6f371c0e0
>> R13: 0000000020000a80 R14: 0030656c69662f2e R15: 00007fd6f374f7a8
>> </TASK>
>> INFO: task syz-executor359:5304 blocked for more than 145 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:26504 pid:5304 ppid:5112 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> io_schedule+0x8c/0x100 kernel/sched/core.c:8884
>> folio_wait_bit_common+0x86c/0x12b0 mm/filemap.c:1301
>> folio_wait_writeback+0xec/0x1f0 mm/page-writeback.c:3127
>> migrate_folio_unmap mm/migrate.c:1192 [inline]
>> migrate_pages_batch mm/migrate.c:1685 [inline]
>> migrate_pages+0x2d50/0x6610 mm/migrate.c:1973
>> do_mbind mm/mempolicy.c:1338 [inline]
>> kernel_mbind mm/mempolicy.c:1485 [inline]
>> __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> __se_sys_mbind+0x75a/0x9c0 mm/mempolicy.c:1555
>> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
>> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fd6f36ca719
>> RSP: 002b:00007fd6eb3552e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
>> RAX: ffffffffffffffda RBX: 00007fd6f374f7b0 RCX: 00007fd6f36ca719
>> RDX: 0000000000000000 RSI: 0000000000800000 RDI: 0000000020001000
>> RBP: 00007fd6f371c604 R08: 0000000000000000 R09: 0000000000000002
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd6f371c0e0
>> R13: 0000000020000a80 R14: 0030656c69662f2e R15: 00007fd6f374f7b8
>> </TASK>
>> INFO: task syz-executor359:5460 blocked for more than 146 seconds.
>> Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor359 state:D stack:26520 pid:5460 ppid:5115 flags:0x00004004
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5304 [inline]
>> __schedule+0x17d8/0x4990 kernel/sched/core.c:6622
>> schedule+0xc3/0x180 kernel/sched/core.c:6698
>> schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
>> rwsem_down_read_slowpath+0x5f4/0x950 kernel/locking/rwsem.c:1086
>> __down_read_common+0x61/0x2c0 kernel/locking/rwsem.c:1250
>> mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
>> RIP: 0033:0x7fd6f371b888
>> RSP: 002b:00007ffd6fdf2398 EFLAGS: 00010206
>> RAX: 00007fd6f374ebd0 RBX: 00007fd6f374d1a8 RCX: 0000000000000001
>> RDX: 00007fd6f3688d30 RSI: 0000000000000000 RDI: 00007fd6f374ebd0
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000010
>> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
>> R13: 0000000000000001 R14: 00007fd6f37543e0 R15: 0000000000000001
>> </TASK>
>> Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings
>>
>> Showing all locks held in the system:
>> 3 locks held by kworker/u4:0/9:
>> #0: ffff8881451bb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc900000e7d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> #2: ffff88807dfe20e0 (&type->s_umount_key#43){++++}-{3:3}, at: trylock_super+0x1f/0xf0 fs/super.c:414
>> 1 lock held by rcu_tasks_kthre/12:
>> #0: ffffffff8d127cf0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510
>> 1 lock held by rcu_tasks_trace/13:
>> #0: ffffffff8d1284f0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510
>> 1 lock held by khungtaskd/28:
>> #0: ffffffff8d127b20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
>> 3 locks held by kworker/u4:2/41:
>> #0: ffff8881451bb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc90000b27d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> #2: ffff88801d8680e0 (&type->s_umount_key#43){++++}-{3:3}, at: trylock_super+0x1f/0xf0 fs/super.c:414
>> 3 locks held by kworker/u4:4/75:
>> #0: ffff8881451bb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc900020efd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> #2: ffff88802c2640e0 (&type->s_umount_key#43){++++}-{3:3}, at: trylock_super+0x1f/0xf0 fs/super.c:414
>> 2 locks held by kworker/1:2/2494:
>> #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc9000a86fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> 2 locks held by getty/4750:
>> #0: ffff88814a0e2098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:244
>> #1: ffffc900015802f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6ab/0x1db0 drivers/tty/n_tty.c:2177
>> 1 lock held by syz-executor359/5222:
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> 2 locks held by syz-executor359/5223:
>> #0: ffff888021e0f768 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x254/0x2f0 fs/file.c:1046
>> #1: ffff88802c264460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580
>> 1 lock held by syz-executor359/5229:
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1312 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1485 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> #0: ffff88807d1df698 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x47d/0x9c0 mm/mempolicy.c:1555
>> 1 lock held by syz-executor359/5296:
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> 2 locks held by syz-executor359/5298:
>> #0: ffff88807e2b0fe8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x254/0x2f0 fs/file.c:1046
>> #1: ffff88807dfe2460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580
>> 1 lock held by syz-executor359/5304:
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1312 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1485 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> #0: ffff88802cd0ae98 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x47d/0x9c0 mm/mempolicy.c:1555
>> 1 lock held by syz-executor359/5460:
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> 2 locks held by syz-executor359/5461:
>> #0: ffff88801da66ae8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x254/0x2f0 fs/file.c:1046
>> #1: ffff888148d0a460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580
>> 1 lock held by syz-executor359/5467:
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1312 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1485 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> #0: ffff888022485298 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x47d/0x9c0 mm/mempolicy.c:1555
>> 1 lock held by syz-executor359/5570:
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> 2 locks held by syz-executor359/5571:
>> #0: ffff88807838a5e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x254/0x2f0 fs/file.c:1046
>> #1: ffff88801d868460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580
>> 1 lock held by syz-executor359/5575:
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1312 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1485 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> #0: ffff88807d295298 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x47d/0x9c0 mm/mempolicy.c:1555
>> 1 lock held by syz-executor359/5572:
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1358 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1498 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x558/0x8a0 arch/x86/mm/fault.c:1554
>> 2 locks held by syz-executor359/5573:
>> #0: ffff888026d84d68 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x254/0x2f0 fs/file.c:1046
>> #1: ffff88807b6ac460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x26d/0xbb0 fs/read_write.c:580
>> 1 lock held by syz-executor359/5576:
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: do_mbind mm/mempolicy.c:1312 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: kernel_mbind mm/mempolicy.c:1485 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: __do_sys_mbind mm/mempolicy.c:1559 [inline]
>> #0: ffff88807d1dc098 (&mm->mmap_lock){++++}-{3:3}, at: __se_sys_mbind+0x47d/0x9c0 mm/mempolicy.c:1555
>> 3 locks held by kworker/u4:3/5614:
>> #0: ffff8881451bb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc90004defd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> #2: ffff88807b6ac0e0 (&type->s_umount_key#43){++++}-{3:3}, at: trylock_super+0x1f/0xf0 fs/super.c:414
>> 3 locks held by kworker/u4:5/6087:
>> #0: ffff8881451bb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x77f/0x13a0
>> #1: ffffc900055b7d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7c6/0x13a0 kernel/workqueue.c:2365
>> #2: ffff888148d0a0e0 (&type->s_umount_key#43){++++}-{3:3}, at: trylock_super+0x1f/0xf0 fs/super.c:414
>> 1 lock held by syz-executor359/12461:
>> #0: ffffffff8d12d1f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:293 [inline]
>> #0: ffffffff8d12d1f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a3/0x890 kernel/rcu/tree_exp.h:989
>>
>> =============================================
>>
>> NMI backtrace for cpu 0
>> CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
>> Call Trace:
>> <TASK>
>> __dump_stack lib/dump_stack.c:88 [inline]
>> dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
>> nmi_cpu_backtrace+0x4e5/0x560 lib/nmi_backtrace.c:113
>> nmi_trigger_cpumask_backtrace+0x1b4/0x410 lib/nmi_backtrace.c:62
>> trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
>> check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
>> watchdog+0x1024/0x1070 kernel/hung_task.c:379
>> kthread+0x270/0x300 kernel/kthread.c:376
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>> </TASK>
>> Sending NMI from CPU 0 to CPUs 1:
>> NMI backtrace for cpu 1
>> CPU: 1 PID: 6343 Comm: kworker/u4:9 Not tainted 6.2.0-syzkaller-10827-g489fa31ea873 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
>> Workqueue: events_unbound toggle_allocation_gate
>> RIP: 0010:rcu_sync_is_idle include/linux/rcu_sync.h:36 [inline]
>> RIP: 0010:percpu_up_read include/linux/percpu-rwsem.h:105 [inline]
>> RIP: 0010:cpus_read_unlock+0x5f/0x130 kernel/cpu.c:322
>> Code: 85 db 74 1b e8 c2 4f 20 00 89 c3 31 ff 89 c6 e8 87 23 39 00 85
> db 74 5b e8 ce 1f 39 00 eb 05 e8 c7 1f 39 00 8b 1d 41 be a8 0b <31> ff
> 89 de e8 68 23 39 00 85 db 0f 85 8c 00 00 00 e8 ab 1f 39 00
>> RSP: 0018:ffffc90005757b70 EFLAGS: 00000293
>> RAX: ffffffff81538cb2 RBX: 0000000000000000 RCX: ffff888028643a80
>> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
>> RBP: ffffc90005757c50 R08: ffffffff81538ca9 R09: fffffbfff1ce8d2e
>> R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
>> R13: 1ffff1104779cc03 R14: 0000000000000000 R15: 1ffff92000aeaf70
>> FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007ffd6fdf0bb8 CR3: 000000000cf30000 CR4: 00000000003506e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>> <TASK>
>> toggle_allocation_gate+0xb5/0x250 mm/kfence/core.c:799
>> process_one_work+0x915/0x13a0 kernel/workqueue.c:2390
>> worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
>> kthread+0x270/0x300 kernel/kthread.c:376
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>> </TASK>
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>> syzbot can test patches for this issue, for details see:
>> https://goo.gl/tpsmEJ#testing-patches
>>