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Subject[syzbot] possible deadlock in f2fs_convert_inline_inode
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Hello,

syzbot found the following issue on:

HEAD commit: 764822972d64 Merge tag 'nfsd-6.2' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123f0db7880000
kernel config: https://syzkaller.appspot.com/x/.config?x=56488a108d0b7cb8
dashboard link: https://syzkaller.appspot.com/bug?extid=77204b1ec54dde7158d6
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/10cd94ab1fd0/disk-76482297.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4116972537f8/vmlinux-76482297.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4a815774b892/bzImage-76482297.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+77204b1ec54dde7158d6@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.0-syzkaller-03225-g764822972d64 #0 Not tainted
------------------------------------------------------
syz-executor.2/12276 is trying to acquire lock:
ffff888022de03b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2180 [inline]
ffff888022de03b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_lock_op fs/f2fs/f2fs.h:2223 [inline]
ffff888022de03b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_convert_inline_inode+0x481/0x8f0 fs/f2fs/inline.c:219

but task is already holding lock:
ffff88801c84e6d8 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
ffff88801c84e6d8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x276/0x1210 arch/x86/mm/fault.c:1369

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&mm->mmap_lock#2){++++}-{3:3}:
__might_fault mm/memory.c:5645 [inline]
__might_fault+0x10c/0x180 mm/memory.c:5638
_copy_to_user+0x29/0x150 lib/usercopy.c:29
copy_to_user include/linux/uaccess.h:169 [inline]
f2fs_ioc_get_encryption_pwsalt+0x2b2/0x370 fs/f2fs/file.c:2349
__f2fs_ioctl+0x1755/0xa7c0 fs/f2fs/file.c:4151
f2fs_ioctl+0x18e/0x220 fs/f2fs/file.c:4224
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #3 (&sbi->sb_lock){++++}-{3:3}:
down_write+0x94/0x220 kernel/locking/rwsem.c:1562
f2fs_down_write fs/f2fs/f2fs.h:2205 [inline]
f2fs_handle_error+0x8e/0x200 fs/f2fs/super.c:3898
check_block_count+0x440/0x4f0 fs/f2fs/segment.h:771
build_sit_entries fs/f2fs/segment.c:4432 [inline]
f2fs_build_segment_manager+0x5a30/0xa670 fs/f2fs/segment.c:5123
f2fs_fill_super+0x3a73/0x77a0 fs/f2fs/super.c:4300
mount_bdev+0x351/0x410 fs/super.c:1359
legacy_get_tree+0x109/0x220 fs/fs_context.c:610
vfs_get_tree+0x8d/0x2f0 fs/super.c:1489
do_new_mount fs/namespace.c:3145 [inline]
path_mount+0x132a/0x1e20 fs/namespace.c:3475
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3697 [inline]
__se_sys_mount fs/namespace.c:3674 [inline]
__x64_sys_mount+0x283/0x300 fs/namespace.c:3674
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&array[i].journal_rwsem){++++}-{3:3}:
down_read+0x9c/0x450 kernel/locking/rwsem.c:1509
scan_curseg_cache+0xa7/0x3b0 fs/f2fs/node.c:2401
__f2fs_build_free_nids+0x761/0xe10 fs/f2fs/node.c:2513
f2fs_build_free_nids fs/f2fs/node.c:2528 [inline]
f2fs_build_node_manager+0x2007/0x2fb0 fs/f2fs/node.c:3313
f2fs_fill_super+0x3a95/0x77a0 fs/f2fs/super.c:4306
mount_bdev+0x351/0x410 fs/super.c:1359
legacy_get_tree+0x109/0x220 fs/fs_context.c:610
vfs_get_tree+0x8d/0x2f0 fs/super.c:1489
do_new_mount fs/namespace.c:3145 [inline]
path_mount+0x132a/0x1e20 fs/namespace.c:3475
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3697 [inline]
__se_sys_mount fs/namespace.c:3674 [inline]
__x64_sys_mount+0x283/0x300 fs/namespace.c:3674
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&nm_i->nat_tree_lock){++++}-{3:3}:
down_read+0x9c/0x450 kernel/locking/rwsem.c:1509
f2fs_down_read fs/f2fs/f2fs.h:2180 [inline]
f2fs_get_node_info+0x1ac/0x1070 fs/f2fs/node.c:560
__allocate_data_block+0x180/0xbf0 fs/f2fs/data.c:1425
f2fs_map_blocks+0x1505/0x3600 fs/f2fs/data.c:1608
f2fs_preallocate_blocks fs/f2fs/file.c:4451 [inline]
f2fs_file_write_iter+0x10f0/0x3160 fs/f2fs/file.c:4654
call_write_iter include/linux/fs.h:2186 [inline]
do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:735
do_iter_write+0x182/0x700 fs/read_write.c:861
vfs_iter_write+0x74/0xa0 fs/read_write.c:902
iter_file_splice_write+0x745/0xc90 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0x114/0x180 fs/splice.c:931
splice_direct_to_actor+0x335/0x8a0 fs/splice.c:886
do_splice_direct+0x1ab/0x280 fs/splice.c:974
do_sendfile+0xb19/0x1270 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64 fs/read_write.c:1309 [inline]
__x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (
&sbi->cp_rwsem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
down_read+0x9c/0x450 kernel/locking/rwsem.c:1509
f2fs_down_read fs/f2fs/f2fs.h:2180 [inline]
f2fs_lock_op fs/f2fs/f2fs.h:2223 [inline]
f2fs_convert_inline_inode+0x481/0x8f0 fs/f2fs/inline.c:219
f2fs_vm_page_mkwrite+0x308/0x1c90 fs/f2fs/file.c:79
do_page_mkwrite+0x19b/0x680 mm/memory.c:2977
do_shared_fault mm/memory.c:4618 [inline]
do_fault mm/memory.c:4686 [inline]
handle_pte_fault mm/memory.c:4954 [inline]
__handle_mm_fault+0x2280/0x3a40 mm/memory.c:5096
handle_mm_fault+0x1cc/0x780 mm/memory.c:5217
do_user_addr_fault+0x475/0x1210 arch/x86/mm/fault.c:1428
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

other info that might help us debug this:

Chain exists of:
&sbi->cp_rwsem --> &sbi->sb_lock --> &mm->mmap_lock#2

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&mm->mmap_lock#2);
lock(&sbi->sb_lock);
lock(&mm->mmap_lock#2);
lock(&sbi->cp_rwsem);

*** DEADLOCK ***

1 lock held by syz-executor.2/12276:
#0: ffff88801c84e6d8 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88801c84e6d8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x276/0x1210 arch/x86/mm/fault.c:1369

stack backtrace:
CPU: 1 PID: 12276 Comm: syz-executor.2 Not tainted 6.1.0-syzkaller-03225-g764822972d64 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
down_read+0x9c/0x450 kernel/locking/rwsem.c:1509
f2fs_down_read fs/f2fs/f2fs.h:2180 [inline]
f2fs_lock_op fs/f2fs/f2fs.h:2223 [inline]
f2fs_convert_inline_inode+0x481/0x8f0 fs/f2fs/inline.c:219
f2fs_vm_page_mkwrite+0x308/0x1c90 fs/f2fs/file.c:79
do_page_mkwrite+0x19b/0x680 mm/memory.c:2977
do_shared_fault mm/memory.c:4618 [inline]
do_fault mm/memory.c:4686 [inline]
handle_pte_fault mm/memory.c:4954 [inline]
__handle_mm_fault+0x2280/0x3a40 mm/memory.c:5096
handle_mm_fault+0x1cc/0x780 mm/memory.c:5217
do_user_addr_fault+0x475/0x1210 arch/x86/mm/fault.c:1428
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x7f9fd622bd79
Code: 48 8b 04 24 48 85 c0 74 17 48 8b 54 24 18 48 0f ca 48 89 54 24 18 48 83 f8 01 0f 85 9b 02 00 00 48 8b 44 24 10 48 8b 54 24 18 <48> 89 10 e9 c2 fd ff ff 48 8b 44 24 10 0f b7 10 48 8b 04 24 48 85
RSP: 002b:00007fff19a9e770 EFLAGS: 00010246
RAX: 00000000200002c0 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000020000100 RSI: 0000000000000000 RDI: 000055555586e2e8
RBP: 00007fff19a9e868 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f9fd5e10898 R11: 0000000000000246 R12: 00000000001aa76f
R13: 00007fff19a9e890 R14: 00007f9fd63abf80 R15: 0000000000000032
</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@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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