Message-ID: <000000000000c3329c05fe4f8aa0@google.com>
Date:   Sat, 17 Jun 2023 02:01:07 -0700
From:   syzbot <syzbot+c0e3db4f9cd6e05cadd3@...kaller.appspotmail.com>
To:     chao@...nel.org, jaegeuk@...nel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: [syzbot] [f2fs?] possible deadlock in f2fs_file_mmap

Hello,

syzbot found the following issue on:

HEAD commit:    b16049b21162 Add linux-next specific files for 20230614
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=134b968d280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d103d5f9125e9fe9
dashboard link: https://syzkaller.appspot.com/bug?extid=c0e3db4f9cd6e05cadd3
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1620a663280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1327629b280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a21dda01fc71/disk-b16049b2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f31e3fc32b7a/vmlinux-b16049b2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3967bcf93010/bzImage-b16049b2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8deff423ac75/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c0e3db4f9cd6e05cadd3@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc6-next-20230614-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor407/5033 is trying to acquire lock:
ffff888076c40a28 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:768 [inline]
ffff888076c40a28 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: f2fs_file_mmap+0x154/0x290 fs/f2fs/file.c:527

but task is already holding lock:
ffff8880787d3768 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:110 [inline]
ffff8880787d3768 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x158/0x3b0 mm/util.c:541

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       down_read+0x9c/0x480 kernel/locking/rwsem.c:1520
       mmap_read_lock include/linux/mmap_lock.h:142 [inline]
       do_user_addr_fault+0xb3d/0x1210 arch/x86/mm/fault.c:1391
       handle_page_fault arch/x86/mm/fault.c:1534 [inline]
       exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
       fault_in_readable+0x129/0x210 mm/gup.c:1928
       fault_in_iov_iter_readable+0x252/0x2c0 lib/iov_iter.c:216
       f2fs_preallocate_blocks fs/f2fs/file.c:4508 [inline]
       f2fs_file_write_iter+0x516/0x2500 fs/f2fs/file.c:4744
       call_write_iter include/linux/fs.h:1865 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x960/0xd70 fs/read_write.c:584
       ksys_write+0x122/0x250 fs/read_write.c:637
       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 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3142 [inline]
       check_prevs_add kernel/locking/lockdep.c:3261 [inline]
       validate_chain kernel/locking/lockdep.c:3876 [inline]
       __lock_acquire+0x2e9d/0x5e20 kernel/locking/lockdep.c:5144
       lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5761
       down_write+0x92/0x200 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:768 [inline]
       f2fs_file_mmap+0x154/0x290 fs/f2fs/file.c:527
       call_mmap include/linux/fs.h:1870 [inline]
       mmap_region+0x99c/0x2770 mm/mmap.c:2675
       do_mmap+0x850/0xee0 mm/mmap.c:1367
       vm_mmap_pgoff+0x1a2/0x3b0 mm/util.c:543
       ksys_mmap_pgoff+0x42b/0x5b0 mm/mmap.c:1413
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&sb->s_type->i_mutex_key#15);
                               lock(&mm->mmap_lock);
  lock(&sb->s_type->i_mutex_key#15);

 *** DEADLOCK ***

1 lock held by syz-executor407/5033:
 #0: ffff8880787d3768 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:110 [inline]
 #0: ffff8880787d3768 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x158/0x3b0 mm/util.c:541

stack backtrace:
CPU: 1 PID: 5033 Comm: syz-executor407 Not tainted 6.4.0-rc6-next-20230614-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 check_noncircular+0x2df/0x3b0 kernel/locking/lockdep.c:2195
 check_prev_add kernel/locking/lockdep.c:3142 [inline]
 check_prevs_add kernel/locking/lockdep.c:3261 [inline]
 validate_chain kernel/locking/lockdep.c:3876 [inline]
 __lock_acquire+0x2e9d/0x5e20 kernel/locking/lockdep.c:5144
 lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5761
 down_write+0x92/0x200 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:768 [inline]
 f2fs_file_mmap+0x154/0x290 fs/f2fs/file.c:527
 call_mmap include/linux/fs.h:1870 [inline]
 mmap_region+0x99c/0x2770 mm/mmap.c:2675
 do_mmap+0x850/0xee0 mm/mmap.c:1367
 vm_mmap_pgoff+0x1a2/0x3b0 mm/util.c:543
 ksys_mmap_pgoff+0x42b/0x5b0 mm/mmap.c:1413
 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
RIP: 0033:0x7f5f44cdf4d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5f3dc292f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f5f44d696f8 RCX: 00007f5f44cdf4d9
RDX: 000000000000000b RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 00007f5f44d696f0 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 00007f5f44d696fc
R13: 656d6974797a616c R14: 746e657478656f6e R15: 0000000000022000
 </TASK>


---
This report is generated by a bot. It may contain errors.
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