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From:   Yang Shi <shy828301@gmail.com>
Date:   Wed, 15 Apr 2020 20:56:19 -0700
Message-ID: <CAHbLzkqeNLyzP21m3iL4KxE8O0MPZW_vkYozwdLCaVKNp_idnA@mail.gmail.com>
Subject: Re: possible deadlock in shmem_mfill_atomic_pte
To:     syzbot <syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>, syzkaller-bugs@googlegroups.com
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#syz test: https://github.com/yang-shi/linux.git
8f9c86c99d278d375ae24b7ea426e1662c5e4009

On Fri, Apr 10, 2020 at 10:16 PM syzbot
<syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit:    ab6f762f printk: queue wake_up_klogd irq_work only if per-..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=158a6b5de00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3010ccb0f380f660
> dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9
> compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12d3c5afe00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e7f51be00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+e27980339d305f2dbfd9@syzkaller.appspotmail.com
>
> ========================================================
> WARNING: possible irq lock inversion dependency detected
> 5.6.0-syzkaller #0 Not tainted
> --------------------------------------------------------
> syz-executor941/7000 just changed the state of lock:
> ffff88808d9b18d8 (&info->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
> ffff88808d9b18d8 (&info->lock){+.+.}-{2:2}, at: shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
> but this lock was taken by another, SOFTIRQ-safe lock in the past:
>  (&xa->xa_lock#4){..-.}-{2:2}
>
>
> and interrupts could create inverse lock ordering between them.
>
>
> other info that might help us debug this:
>  Possible interrupt unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock(&info->lock);
>                                local_irq_disable();
>                                lock(&xa->xa_lock#4);
>                                lock(&info->lock);
>   <Interrupt>
>     lock(&xa->xa_lock#4);
>
>  *** DEADLOCK ***
>
> 2 locks held by syz-executor941/7000:
>  #0: ffff88809edf10e8 (&mm->mmap_sem#2){++++}-{3:3}, at: __mcopy_atomic mm/userfaultfd.c:491 [inline]
>  #0: ffff88809edf10e8 (&mm->mmap_sem#2){++++}-{3:3}, at: mcopy_atomic+0x17a/0x1ba0 mm/userfaultfd.c:632
>  #1: ffff888098e211f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
>  #1: ffff888098e211f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: shmem_mfill_atomic_pte+0xf73/0x1e10 mm/shmem.c:2389
>
> the shortest dependencies between 2nd lock and 1st lock:
>  -> (&xa->xa_lock#4){..-.}-{2:2} {
>     IN-SOFTIRQ-W at:
>                       lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>                       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>                       _raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
>                       test_clear_page_writeback+0x2d8/0xac0 mm/page-writeback.c:2728
>                       end_page_writeback+0x212/0x390 mm/filemap.c:1317
>                       end_bio_bh_io_sync+0xb1/0x110 fs/buffer.c:3012
>                       req_bio_endio block/blk-core.c:245 [inline]
>                       blk_update_request+0x437/0x1070 block/blk-core.c:1472
>                       scsi_end_request+0x7a/0x7f0 drivers/scsi/scsi_lib.c:575
>                       scsi_io_completion+0x178/0x1be0 drivers/scsi/scsi_lib.c:959
>                       blk_done_softirq+0x2f2/0x360 block/blk-softirq.c:37
>                       __do_softirq+0x268/0x80c kernel/softirq.c:292
>                       invoke_softirq kernel/softirq.c:373 [inline]
>                       irq_exit+0x223/0x230 kernel/softirq.c:413
>                       exiting_irq arch/x86/include/asm/apic.h:546 [inline]
>                       do_IRQ+0xfb/0x1d0 arch/x86/kernel/irq.c:263
>                       ret_from_intr+0x0/0x2b
>                       orc_find arch/x86/kernel/unwind_orc.c:164 [inline]
>                       unwind_next_frame+0x20b/0x1cf0 arch/x86/kernel/unwind_orc.c:407
>                       arch_stack_walk+0xb4/0xe0 arch/x86/kernel/stacktrace.c:25
>                       stack_trace_save+0xad/0x150 kernel/stacktrace.c:123
>                       save_stack mm/kasan/common.c:49 [inline]
>                       set_track mm/kasan/common.c:57 [inline]
>                       __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
>                       __do_kmalloc mm/slab.c:3656 [inline]
>                       __kmalloc+0x24b/0x330 mm/slab.c:3665
>                       kmalloc include/linux/slab.h:560 [inline]
>                       tomoyo_realpath_from_path+0xd8/0x630 security/tomoyo/realpath.c:252
>                       tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>                       tomoyo_check_open_permission+0x1b6/0x900 security/tomoyo/file.c:771
>                       security_file_open+0x50/0xc0 security/security.c:1548
>                       do_dentry_open+0x35d/0x10b0 fs/open.c:784
>                       do_open fs/namei.c:3229 [inline]
>                       path_openat+0x2790/0x38b0 fs/namei.c:3346
>                       do_filp_open+0x191/0x3a0 fs/namei.c:3373
>                       do_sys_openat2+0x463/0x770 fs/open.c:1148
>                       do_sys_open fs/open.c:1164 [inline]
>                       ksys_open include/linux/syscalls.h:1386 [inline]
>                       __do_sys_open fs/open.c:1170 [inline]
>                       __se_sys_open fs/open.c:1168 [inline]
>                       __x64_sys_open+0x1af/0x1e0 fs/open.c:1168
>                       do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>                       entry_SYSCALL_64_after_hwframe+0x49/0xb3
>     INITIAL USE at:
>                      lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>                      __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
>                      _raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167
>                      spin_lock_irq include/linux/spinlock.h:378 [inline]
>                      __add_to_page_cache_locked+0x53d/0xc70 mm/filemap.c:855
>                      add_to_page_cache_lru+0x17f/0x4d0 mm/filemap.c:921
>                      do_read_cache_page+0x209/0xd00 mm/filemap.c:2755
>                      read_mapping_page include/linux/pagemap.h:397 [inline]
>                      read_part_sector+0xd8/0x2d0 block/partitions/core.c:643
>                      adfspart_check_ICS+0x45/0x640 block/partitions/acorn.c:360
>                      check_partition block/partitions/core.c:140 [inline]
>                      blk_add_partitions+0x3ce/0x1240 block/partitions/core.c:571
>                      bdev_disk_changed+0x446/0x5d0 fs/block_dev.c:1544
>                      __blkdev_get+0xb2b/0x13d0 fs/block_dev.c:1647
>                      register_disk block/genhd.c:763 [inline]
>                      __device_add_disk+0x95f/0x1040 block/genhd.c:853
>                      add_disk include/linux/genhd.h:294 [inline]
>                      brd_init+0x349/0x42a drivers/block/brd.c:533
>                      do_one_initcall+0x14b/0x350 init/main.c:1157
>                      do_initcall_level+0x101/0x14c init/main.c:1230
>                      do_initcalls+0x59/0x9b init/main.c:1246
>                      kernel_init_freeable+0x2fa/0x418 init/main.c:1450
>                      kernel_init+0xd/0x290 init/main.c:1357
>                      ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>   }
>   ... key      at: [<ffffffff8b5afa68>] xa_init_flags.__key+0x0/0x10
>   ... acquired at:
>    lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>    _raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
>    shmem_uncharge+0x34/0x4c0 mm/shmem.c:341
>    __split_huge_page+0xda8/0x1900 mm/huge_memory.c:2613
>    split_huge_page_to_list+0x10a4/0x15f0 mm/huge_memory.c:2886
>    split_huge_page include/linux/huge_mm.h:204 [inline]
>    shmem_punch_compound+0x17d/0x1c0 mm/shmem.c:814
>    shmem_undo_range+0x5da/0x1d00 mm/shmem.c:870
>    shmem_truncate_range mm/shmem.c:980 [inline]
>    shmem_setattr+0x4e3/0x8a0 mm/shmem.c:1039
>    notify_change+0xad5/0xfb0 fs/attr.c:336
>    do_truncate fs/open.c:64 [inline]
>    do_sys_ftruncate+0x55f/0x690 fs/open.c:195
>    do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>    entry_SYSCALL_64_after_hwframe+0x49/0xb3
>
> -> (&info->lock){+.+.}-{2:2} {
>    HARDIRQ-ON-W at:
>                     lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>                     __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
>                     _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
>                     spin_lock include/linux/spinlock.h:353 [inline]
>                     shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
>                     shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
>                     mfill_atomic_pte mm/userfaultfd.c:449 [inline]
>                     __mcopy_atomic mm/userfaultfd.c:582 [inline]
>                     mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
>                     userfaultfd_copy fs/userfaultfd.c:1743 [inline]
>                     userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
>                     vfs_ioctl fs/ioctl.c:47 [inline]
>                     ksys_ioctl fs/ioctl.c:763 [inline]
>                     __do_sys_ioctl fs/ioctl.c:772 [inline]
>                     __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
>                     do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>                     entry_SYSCALL_64_after_hwframe+0x49/0xb3
>    SOFTIRQ-ON-W at:
>                     lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>                     __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
>                     _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
>                     spin_lock include/linux/spinlock.h:353 [inline]
>                     shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
>                     shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
>                     mfill_atomic_pte mm/userfaultfd.c:449 [inline]
>                     __mcopy_atomic mm/userfaultfd.c:582 [inline]
>                     mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
>                     userfaultfd_copy fs/userfaultfd.c:1743 [inline]
>                     userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
>                     vfs_ioctl fs/ioctl.c:47 [inline]
>                     ksys_ioctl fs/ioctl.c:763 [inline]
>                     __do_sys_ioctl fs/ioctl.c:772 [inline]
>                     __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
>                     do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>                     entry_SYSCALL_64_after_hwframe+0x49/0xb3
>    INITIAL USE at:
>                    lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>                    __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
>                    _raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167
>                    spin_lock_irq include/linux/spinlock.h:378 [inline]
>                    shmem_getpage_gfp+0x2160/0x3120 mm/shmem.c:1882
>                    shmem_getpage mm/shmem.c:154 [inline]
>                    shmem_write_begin+0xcd/0x1a0 mm/shmem.c:2483
>                    generic_perform_write+0x23b/0x4e0 mm/filemap.c:3302
>                    __generic_file_write_iter+0x22b/0x4e0 mm/filemap.c:3431
>                    generic_file_write_iter+0x4a6/0x650 mm/filemap.c:3463
>                    call_write_iter include/linux/fs.h:1907 [inline]
>                    new_sync_write fs/read_write.c:484 [inline]
>                    __vfs_write+0x54c/0x710 fs/read_write.c:497
>                    vfs_write+0x274/0x580 fs/read_write.c:559
>                    ksys_write+0x11b/0x220 fs/read_write.c:612
>                    do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>                    entry_SYSCALL_64_after_hwframe+0x49/0xb3
>  }
>  ... key      at: [<ffffffff8b59f840>] shmem_get_inode.__key+0x0/0x10
>  ... acquired at:
>    mark_lock_irq kernel/locking/lockdep.c:3585 [inline]
>    mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:3935
>    mark_usage kernel/locking/lockdep.c:3852 [inline]
>    __lock_acquire+0xb95/0x2b90 kernel/locking/lockdep.c:4298
>    lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>    __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
>    _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
>    spin_lock include/linux/spinlock.h:353 [inline]
>    shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
>    shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
>    mfill_atomic_pte mm/userfaultfd.c:449 [inline]
>    __mcopy_atomic mm/userfaultfd.c:582 [inline]
>    mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
>    userfaultfd_copy fs/userfaultfd.c:1743 [inline]
>    userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
>    vfs_ioctl fs/ioctl.c:47 [inline]
>    ksys_ioctl fs/ioctl.c:763 [inline]
>    __do_sys_ioctl fs/ioctl.c:772 [inline]
>    __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
>    do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>    entry_SYSCALL_64_after_hwframe+0x49/0xb3
>
>
> stack backtrace:
> CPU: 1 PID: 7000 Comm: syz-executor941 Not tainted 5.6.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1e9/0x30e lib/dump_stack.c:118
>  print_irq_inversion_bug+0xb67/0xe90 kernel/locking/lockdep.c:3447
>  check_usage_backwards+0x13f/0x240 kernel/locking/lockdep.c:3499
>  mark_lock_irq kernel/locking/lockdep.c:3585 [inline]
>  mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:3935
>  mark_usage kernel/locking/lockdep.c:3852 [inline]
>  __lock_acquire+0xb95/0x2b90 kernel/locking/lockdep.c:4298
>  lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
>  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
>  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
>  spin_lock include/linux/spinlock.h:353 [inline]
>  shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
>  shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
>  mfill_atomic_pte mm/userfaultfd.c:449 [inline]
>  __mcopy_atomic mm/userfaultfd.c:582 [inline]
>  mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
>  userfaultfd_copy fs/userfaultfd.c:1743 [inline]
>  userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
>  vfs_ioctl fs/ioctl.c:47 [inline]
>  ksys_ioctl fs/ioctl.c:763 [inline]
>  __do_sys_ioctl fs/ioctl.c:772 [inline]
>  __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
>  do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
>  entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x444399
> Code: 0d d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffd0974a4a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444399
> RDX: 00000000200a0fe0 RSI: 00000000c028aa03 RDI: 0000000000000004
> RBP: 00000000006cf018 R08: 00000000004002e0 R09: 00000000004002e0
> R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000402000
> R13: 0000000000402090 R14: 0000000000000000 R15: 0000000000000000
>
>