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possible deadlock in __do_page_fault (2)




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=100a5f26a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6cfb24468280cd5c
dashboard link: https://syzkaller.appspot.com/bug?extid=606e524a3ca9617cf8c0
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+606e524a3ca9617cf8c0@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc2-next-20190531 #4 Not tainted
------------------------------------------------------
syz-executor.1/28460 is trying to acquire lock:
000000007749dcbb (&mm->mmap_sem#2){++++}, at: do_user_addr_fault arch/x86/mm/fault.c:1407 [inline] 000000007749dcbb (&mm->mmap_sem#2){++++}, at: __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1522

but task is already holding lock:
000000000005b591 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:798 [inline] 000000000005b591 (&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
       do_user_addr_fault arch/x86/mm/fault.c:1407 [inline]
       __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1522
       do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1553
       page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156
       fault_in_pages_readable include/linux/pagemap.h:600 [inline]
       iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426
       generic_perform_write+0x186/0x520 mm/filemap.c:3197
       __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336
       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.1/28460:
#0: 00000000f0dc03f3 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: 000000001d3176fb (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2836 [inline] #1: 000000001d3176fb (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 #2: 000000000005b591 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:798 [inline] #2: 000000000005b591 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x246/0x1070 fs/ext4/file.c:232

stack backtrace:
CPU: 1 PID: 28460 Comm: syz-executor.1 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
 do_user_addr_fault arch/x86/mm/fault.c:1407 [inline]
 __do_page_fault+0x9e9/0xda0 arch/x86/mm/fault.c:1522
 do_page_fault+0x71/0x57d arch/x86/mm/fault.c:1553
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1156
RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:600 [inline]
RIP: 0010:iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:426
Code: 89 f6 41 88 57 e0 e8 48 e5 3c fe 45 85 f6 74 c1 e9 70 fe ff ff e8 b9 e3 3c fe 0f 1f 00 0f ae e8 44 89 f0 48 8b 8d 68 ff ff ff <8a> 11 89 c3 0f 1f 00 41 88 57 d0 31 ff 89 de e8 15 e5 3c fe 85 db
RSP: 0018:ffff88803dde7918 EFLAGS: 00010212
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000002008a17f
RDX: 000000000003eb3f RSI: ffffffff833406b7 RDI: 0000000000000007
RBP: ffff88803dde79b8 R08: ffff8880a83d03c0 R09: 0000000000000004
R10: ffffed1015d26be7 R11: ffff8880ae935f3b R12: 0000000000001000
R13: 0000000000001000 R14: 0000000000000000 R15: ffff88803dde7990
 generic_perform_write+0x186/0x520 mm/filemap.c:3197
 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3336
 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:00007f506babec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279
RDX: 00000000fffffcad RSI: 0000000020000180 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f506babf6d4
R13: 00000000004c8838 R14: 00000000004df120 R15: 00000000ffffffff


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