Re: [syzbot] [mm?] possible deadlock in vma_prepare

[Liam R. Howlett]

* syzbot <syzbot+f25246115d09ea7e956b@xxxxxxxxxxxxxxxxxxxxxxxxx> [241013 14:19]:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    33ce24234fca Add linux-next specific files for 20241008
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17670f07980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4750ca93740b938d
> dashboard link: https://syzkaller.appspot.com/bug?extid=f25246115d09ea7e956b
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ee8dc2df0c57/disk-33ce2423.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/dc473c0fa06e/vmlinux-33ce2423.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/4671f1ca2e61/bzImage-33ce2423.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f25246115d09ea7e956b@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ima: No TPM chip found, activating TPM-bypass!
> Loading compiled-in module X.509 certificates
> Loaded X.509 cert 'Build time autogenerated kernel key: 5a5c91671060ad0cbe3fbddde7d37e27f262e8ee'
> ima: Allocated hash algorithm: sha256
> ima: No architecture policies found
> evm: Initialising EVM extended attributes:
> evm: security.selinux (disabled)
> evm: security.SMACK64 (disabled)
> evm: security.SMACK64EXEC (disabled)
> evm: security.SMACK64TRANSMUTE (disabled)
> evm: security.SMACK64MMAP (disabled)
> evm: security.apparmor
> evm: security.ima
> evm: security.capability
> evm: HMAC attrs: 0x1
> PM:   Magic number: 12:674:139
> video4linux video39: hash matches
> nfc nfc1: hash matches
> block ram4: hash matches
> acpi device:10: hash matches
> printk: legacy console [netcon0] enabled
> netconsole: network logging started
> gtp: GTP module loaded (pdp ctx size 128 bytes)
> rdma_rxe: loaded
> cfg80211: Loading compiled-in X.509 certificates for regulatory database
> Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
> Loaded X.509 cert 'wens: 61c038651aabdcf94bd0ac7ff06c7248db18c600'
> clk: Disabling unused clocks
> ALSA device list:
>   #0: Dummy 1
>   #1: Loopback 1
>   #2: Virtual MIDI Card 1
> md: Waiting for all devices to be available before autodetect
> md: If you don't use raid, use raid=noautodetect
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> EXT4-fs (sda1): mounted filesystem b4773fba-1738-4da0-8a90-0fe043d0a496 ro with ordered data mode. Quota mode: none.
> VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
> devtmpfs: mounted
> Freeing unused kernel image (initmem) memory: 26724K
> Write protecting the kernel read-only data: 219136k
> Freeing unused kernel image (rodata/data gap) memory: 1100K
> x86/mm: Checked W+X mappings: passed, no W+X pages found.
> x86/mm: Checking user space page tables
> x86/mm: Checked W+X mappings: passed, no W+X pages found.
> Failed to set sysctl parameter 'max_rcu_stall_to_panic=1': parameter not found
> Run /sbin/init as init process
> 
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.12.0-rc2-next-20241008-syzkaller #0 Not tainted
> ------------------------------------------------------
> init/1 is trying to acquire lock:
> ffff88802fece5c8 (&anon_vma->rwsem){++++}-{3:3}, at: anon_vma_lock_write include/linux/rmap.h:121 [inline]
> ffff88802fece5c8 (&anon_vma->rwsem){++++}-{3:3}, at: vma_prepare+0x26c/0x4c0 mm/vma.c:181
> 
> but task is already holding lock:
> ffff888025b4d608 (&mapping->i_mmap_rwsem){+.+.}-{3:3}, at: i_mmap_lock_write include/linux/fs.h:507 [inline]
> ffff888025b4d608 (&mapping->i_mmap_rwsem){+.+.}-{3:3}, at: vma_prepare+0x13e/0x4c0 mm/vma.c:167
> 
> which lock already depends on the new lock.
> 
> 
> the existing dependency chain (in reverse order) is:
> 
> -> #2 (&mapping->i_mmap_rwsem){+.+.}-{3:3}:
>        lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
>        down_write+0x99/0x220 kernel/locking/rwsem.c:1577
>        i_mmap_lock_write include/linux/fs.h:507 [inline]
>        dma_resv_lockdep+0x4ec/0x8e0 drivers/dma-buf/dma-resv.c:794
>        do_one_initcall+0x248/0x880 init/main.c:1266
>        do_initcall_level+0x157/0x210 init/main.c:1328
>        do_initcalls+0x3f/0x80 init/main.c:1344
>        kernel_init_freeable+0x435/0x5d0 init/main.c:1577
>        kernel_init+0x1d/0x2b0 init/main.c:1466
>        ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> 
> -> #1 (fs_reclaim){+.+.}-{0:0}:
>        lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
>        __fs_reclaim_acquire mm/page_alloc.c:3870 [inline]
>        fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3884
>        might_alloc include/linux/sched/mm.h:327 [inline]
>        prepare_alloc_pages+0x147/0x5d0 mm/page_alloc.c:4529
>        __alloc_pages_noprof+0x166/0x6c0 mm/page_alloc.c:4758
>        alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
>        pagetable_alloc_noprof include/linux/mm.h:2898 [inline]
>        pmd_alloc_one_noprof include/asm-generic/pgalloc.h:138 [inline]
>        __pmd_alloc+0x91/0x620 mm/memory.c:6342
>        pmd_alloc include/linux/mm.h:2861 [inline]
>        alloc_new_pmd mm/mremap.c:96 [inline]
>        move_page_tables+0x1c37/0x1f80 mm/mremap.c:610
>        relocate_vma_down+0x3ff/0x630 mm/mmap.c:2308
>        setup_arg_pages+0x668/0xc10 fs/exec.c:810
>        load_elf_binary+0xb7d/0x2710 fs/binfmt_elf.c:1014
>        search_binary_handler fs/exec.c:1752 [inline]
>        exec_binprm fs/exec.c:1794 [inline]
>        bprm_execve+0xaf8/0x1770 fs/exec.c:1845
>        kernel_execve+0x931/0xa50 fs/exec.c:2012
>        try_to_run_init_process init/main.c:1394 [inline]
>        kernel_init+0xed/0x2b0 init/main.c:1522
>        ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> 
> -> #0 (&anon_vma->rwsem){++++}-{3:3}:
>        check_prev_add kernel/locking/lockdep.c:3161 [inline]
>        check_prevs_add kernel/locking/lockdep.c:3280 [inline]
>        validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
>        __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
>        lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
>        down_write+0x99/0x220 kernel/locking/rwsem.c:1577
>        anon_vma_lock_write include/linux/rmap.h:121 [inline]
>        vma_prepare+0x26c/0x4c0 mm/vma.c:181
>        __split_vma+0x9b7/0xc50 mm/vma.c:419
>        split_vma mm/vma.c:460 [inline]
>        vma_modify+0x153a/0x1a80 mm/vma.c:1433
>        vma_modify_flags+0x3a9/0x420 mm/vma.c:1451
>        mprotect_fixup+0x45a/0xaa0 mm/mprotect.c:664
>        do_mprotect_pkey+0x8e0/0xd80 mm/mprotect.c:838
>        __do_sys_mprotect mm/mprotect.c:859 [inline]
>        __se_sys_mprotect mm/mprotect.c:856 [inline]
>        __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:856
>        do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>        do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>        entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> other info that might help us debug this:
> 
> Chain exists of:
>   &anon_vma->rwsem --> fs_reclaim --> &mapping->i_mmap_rwsem
> 
>  Possible unsafe locking scenario:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(&mapping->i_mmap_rwsem);
>                                lock(fs_reclaim);
>                                lock(&mapping->i_mmap_rwsem);
>   lock(&anon_vma->rwsem);
> 
>  *** DEADLOCK ***

Interesting, fs_reclaim was giving me issues with the ordering of locks
in my other work for vma locks & i_mmap_rwsem and the mmap fixed
changes.

> 
> 2 locks held by init/1:
>  #0: ffff88802e138198 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline]
>  #0: ffff88802e138198 (&mm->mmap_lock){++++}-{3:3}, at: do_mprotect_pkey+0x21b/0xd80 mm/mprotect.c:740
>  #1: ffff888025b4d608 (&mapping->i_mmap_rwsem){+.+.}-{3:3}, at: i_mmap_lock_write include/linux/fs.h:507 [inline]
>  #1: ffff888025b4d608 (&mapping->i_mmap_rwsem){+.+.}-{3:3}, at: vma_prepare+0x13e/0x4c0 mm/vma.c:167
> 
> stack backtrace:
> CPU: 0 UID: 0 PID: 1 Comm: init Not tainted 6.12.0-rc2-next-20241008-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
>  print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
>  check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
>  check_prev_add kernel/locking/lockdep.c:3161 [inline]
>  check_prevs_add kernel/locking/lockdep.c:3280 [inline]
>  validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
>  __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
>  lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
>  down_write+0x99/0x220 kernel/locking/rwsem.c:1577
>  anon_vma_lock_write include/linux/rmap.h:121 [inline]
>  vma_prepare+0x26c/0x4c0 mm/vma.c:181
>  __split_vma+0x9b7/0xc50 mm/vma.c:419
>  split_vma mm/vma.c:460 [inline]
>  vma_modify+0x153a/0x1a80 mm/vma.c:1433
>  vma_modify_flags+0x3a9/0x420 mm/vma.c:1451
>  mprotect_fixup+0x45a/0xaa0 mm/mprotect.c:664
>  do_mprotect_pkey+0x8e0/0xd80 mm/mprotect.c:838
>  __do_sys_mprotect mm/mprotect.c:859 [inline]
>  __se_sys_mprotect mm/mprotect.c:856 [inline]
>  __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:856
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f7347f7dbb7
> Code: 00 00 00 b8 0b 00 00 00 0f 05 48 3d 01 f0 ff ff 73 01 c3 48 8d 0d b9 46 01 00 f7 d8 89 01 48 83 c8 ff c3 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8d 0d 99 46 01 00 f7 d8 89 01 48 83
> RSP: 002b:00007ffde248d688 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
> RAX: ffffffffffffffda RBX: 00007f7347f5a5c0 RCX: 00007f7347f7dbb7
> RDX: 0000000000000001 RSI: 0000000000004000 RDI: 00007f7347e84000
> RBP: 00007ffde248d7a0 R08: 00007ffde2480000 R09: 00007f7347f91ab0
> R10: 00007f7347ceaab8 R11: 0000000000000206 R12: 00007f7347f5a5c0
> R13: 00007f7347f85eda R14: 00007f7347e87bf8 R15: 00007f7347e87b70
>  </TASK>
> 
> 
> ---
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