possible deadlock in get_user_pages_unlocked (2)

* possible deadlock in get_user_pages_unlocked (2)
@ 2019-06-01  6:08 syzbot
  2019-06-04 21:19 ` syzbot
  2019-06-05  1:16 ` syzbot
  0 siblings, 2 replies; 4+ messages in thread
From: syzbot @ 2019-06-01  6:08 UTC (permalink / raw)
  To: akpm, aneesh.kumar, dan.j.williams, ira.weiny, jhubbard,
	keith.busch, linux-kernel, linux-mm, rppt, sfr, syzkaller-bugs

Hello,

syzbot found the following crash on:

HEAD commit:    3c09c195 Add linux-next specific files for 20190531
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13b36b9aa00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6cfb24468280cd5c
dashboard link: https://syzkaller.appspot.com/bug?extid=e1374b2ec8f6a25ab2e5
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e1374b2ec8f6a25ab2e5@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc2-next-20190531 #4 Not tainted
------------------------------------------------------
syz-executor.5/29536 is trying to acquire lock:
0000000031b33a56 (&mm->mmap_sem#2){++++}, at:  
get_user_pages_unlocked+0xfc/0x4a0 mm/gup.c:1174

but task is already holding lock:
00000000e8d693f5 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock  
include/linux/fs.h:798 [inline]
00000000e8d693f5 (&sb->s_type->i_mutex_key#10){++++}, at:  
ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#10){++++}:
        down_write+0x38/0xa0 kernel/locking/rwsem.c:66
        inode_lock include/linux/fs.h:778 [inline]
        process_measurement+0x15ae/0x15e0  
security/integrity/ima/ima_main.c:228
        ima_file_mmap+0x11a/0x130 security/integrity/ima/ima_main.c:370
        security_file_mprotect+0xd5/0x100 security/security.c:1430
        do_mprotect_pkey+0x537/0xa30 mm/mprotect.c:550
        __do_sys_pkey_mprotect mm/mprotect.c:590 [inline]
        __se_sys_pkey_mprotect mm/mprotect.c:587 [inline]
        __x64_sys_pkey_mprotect+0x97/0xf0 mm/mprotect.c:587
        do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&mm->mmap_sem#2){++++}:
        lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300
        down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24
        get_user_pages_unlocked+0xfc/0x4a0 mm/gup.c:1174
        __gup_longterm_unlocked mm/gup.c:2193 [inline]
        get_user_pages_fast+0x43f/0x530 mm/gup.c:2245
        iov_iter_get_pages+0x2c2/0xf80 lib/iov_iter.c:1287
        dio_refill_pages fs/direct-io.c:171 [inline]
        dio_get_page fs/direct-io.c:215 [inline]
        do_direct_IO fs/direct-io.c:983 [inline]
        do_blockdev_direct_IO+0x3f7b/0x8e00 fs/direct-io.c:1336
        __blockdev_direct_IO+0xa1/0xca fs/direct-io.c:1422
        ext4_direct_IO_write fs/ext4/inode.c:3782 [inline]
        ext4_direct_IO+0xaa7/0x1bb0 fs/ext4/inode.c:3909
        generic_file_direct_write+0x20a/0x4a0 mm/filemap.c:3110
        __generic_file_write_iter+0x2ee/0x630 mm/filemap.c:3293
        ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266
        call_write_iter include/linux/fs.h:1870 [inline]
        new_sync_write+0x4d3/0x770 fs/read_write.c:483
        __vfs_write+0xe1/0x110 fs/read_write.c:496
        vfs_write+0x268/0x5d0 fs/read_write.c:558
        ksys_write+0x14f/0x290 fs/read_write.c:611
        __do_sys_write fs/read_write.c:623 [inline]
        __se_sys_write fs/read_write.c:620 [inline]
        __x64_sys_write+0x73/0xb0 fs/read_write.c:620
        do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
        entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&sb->s_type->i_mutex_key#10);
                                lock(&mm->mmap_sem#2);
                                lock(&sb->s_type->i_mutex_key#10);
   lock(&mm->mmap_sem#2);

  *** DEADLOCK ***

3 locks held by syz-executor.5/29536:
  #0: 000000007070e315 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110  
fs/file.c:801
  #1: 000000001278f3d0 (sb_writers#3){.+.+}, at: file_start_write  
include/linux/fs.h:2836 [inline]
  #1: 000000001278f3d0 (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0  
fs/read_write.c:557
  #2: 00000000e8d693f5 (&sb->s_type->i_mutex_key#10){++++}, at:  
inode_trylock include/linux/fs.h:798 [inline]
  #2: 00000000e8d693f5 (&sb->s_type->i_mutex_key#10){++++}, at:  
ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232

stack backtrace:
CPU: 0 PID: 29536 Comm: syz-executor.5 Not tainted 5.2.0-rc2-next-20190531  
#4
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+0x172/0x1f0 lib/dump_stack.c:113
  print_circular_bug.cold+0x1cc/0x28f kernel/locking/lockdep.c:1566
  check_prev_add kernel/locking/lockdep.c:2311 [inline]
  check_prevs_add kernel/locking/lockdep.c:2419 [inline]
  validate_chain kernel/locking/lockdep.c:2801 [inline]
  __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3790
  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4300
  down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24
  get_user_pages_unlocked+0xfc/0x4a0 mm/gup.c:1174
  __gup_longterm_unlocked mm/gup.c:2193 [inline]
  get_user_pages_fast+0x43f/0x530 mm/gup.c:2245
  iov_iter_get_pages+0x2c2/0xf80 lib/iov_iter.c:1287
  dio_refill_pages fs/direct-io.c:171 [inline]
  dio_get_page fs/direct-io.c:215 [inline]
  do_direct_IO fs/direct-io.c:983 [inline]
  do_blockdev_direct_IO+0x3f7b/0x8e00 fs/direct-io.c:1336
  __blockdev_direct_IO+0xa1/0xca fs/direct-io.c:1422
  ext4_direct_IO_write fs/ext4/inode.c:3782 [inline]
  ext4_direct_IO+0xaa7/0x1bb0 fs/ext4/inode.c:3909
  generic_file_direct_write+0x20a/0x4a0 mm/filemap.c:3110
  __generic_file_write_iter+0x2ee/0x630 mm/filemap.c:3293
  ext4_file_write_iter+0x332/0x1070 fs/ext4/file.c:266
  call_write_iter include/linux/fs.h:1870 [inline]
  new_sync_write+0x4d3/0x770 fs/read_write.c:483
  __vfs_write+0xe1/0x110 fs/read_write.c:496
  vfs_write+0x268/0x5d0 fs/read_write.c:558
  ksys_write+0x14f/0x290 fs/read_write.c:611
  __do_sys_write fs/read_write.c:623 [inline]
  __se_sys_write fs/read_write.c:620 [inline]
  __x64_sys_write+0x73/0xb0 fs/read_write.c:620
  do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f65e9a0fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279
RDX: 000000010000000d RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000075bfc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f65e9a106d4
R13: 00000000004c8e8a R14: 00000000004dfae0 R15: 00000000ffffffff

---
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