audit: type=1800 audit(1546544132.316:30): pid=7499 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0
======================================================
WARNING: possible circular locking dependency detected
4.20.0+ #7 Not tainted
------------------------------------------------------
syz-executor673/7657 is trying to acquire lock:
000000003b5eb535 (&mm->mmap_sem){++++}, at: do_user_addr_fault arch/x86/mm/fault.c:1426 [inline]
000000003b5eb535 (&mm->mmap_sem){++++}, at: __do_page_fault+0x9c2/0xd60 arch/x86/mm/fault.c:1541
but task is already holding lock:
00000000972faa88 (&sb->s_type->i_mutex_key#12){+.+.}, at: inode_lock include/linux/fs.h:757 [inline]
00000000972faa88 (&sb->s_type->i_mutex_key#12){+.+.}, at: generic_file_write_iter+0xe5/0x6a0 mm/filemap.c:3358
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&sb->s_type->i_mutex_key#12){+.+.}:
down_write+0x8a/0x130 kernel/locking/rwsem.c:70
inode_lock include/linux/fs.h:757 [inline]
shmem_fallocate+0x168/0x1200 mm/shmem.c:2633
ashmem_shrink_scan drivers/staging/android/ashmem.c:455 [inline]
ashmem_shrink_scan+0x239/0x630 drivers/staging/android/ashmem.c:439
ashmem_ioctl+0x38a/0x12c0 drivers/staging/android/ashmem.c:797
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (ashmem_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
ashmem_mmap+0x55/0x520 drivers/staging/android/ashmem.c:361
call_mmap include/linux/fs.h:1867 [inline]
mmap_region+0xde5/0x1ca0 mm/mmap.c:1786
do_mmap+0xa09/0x1220 mm/mmap.c:1559
do_mmap_pgoff include/linux/mm.h:2378 [inline]
vm_mmap_pgoff+0x20b/0x2b0 mm/util.c:350
ksys_mmap_pgoff+0x4f8/0x650 mm/mmap.c:1609
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
__x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&mm->mmap_sem){++++}:
lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841
down_read+0x8d/0x120 kernel/locking/rwsem.c:24
do_user_addr_fault arch/x86/mm/fault.c:1426 [inline]
__do_page_fault+0x9c2/0xd60 arch/x86/mm/fault.c:1541
do_page_fault+0xe6/0x7d8 arch/x86/mm/fault.c:1572
page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
fault_in_pages_readable include/linux/pagemap.h:611 [inline]
iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:425
generic_perform_write+0x202/0x6b0 mm/filemap.c:3198
__generic_file_write_iter+0x25e/0x630 mm/filemap.c:3333
generic_file_write_iter+0x34e/0x6a0 mm/filemap.c:3361
call_write_iter include/linux/fs.h:1862 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x764/0xb40 fs/read_write.c:487
vfs_write+0x20c/0x580 fs/read_write.c:549
ksys_write+0x105/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Chain exists of:
&mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#12
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sb->s_type->i_mutex_key#12);
lock(ashmem_mutex);
lock(&sb->s_type->i_mutex_key#12);
lock(&mm->mmap_sem);
*** DEADLOCK ***
2 locks held by syz-executor673/7657:
#0: 00000000da3eb5bf (sb_writers#5){.+.+}, at: file_start_write include/linux/fs.h:2815 [inline]
#0: 00000000da3eb5bf (sb_writers#5){.+.+}, at: vfs_write+0x429/0x580 fs/read_write.c:548
#1: 00000000972faa88 (&sb->s_type->i_mutex_key#12){+.+.}, at: inode_lock include/linux/fs.h:757 [inline]
#1: 00000000972faa88 (&sb->s_type->i_mutex_key#12){+.+.}, at: generic_file_write_iter+0xe5/0x6a0 mm/filemap.c:3358
stack backtrace:
CPU: 0 PID: 7657 Comm: syz-executor673 Not tainted 4.20.0+ #7
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+0x1db/0x2d0 lib/dump_stack.c:113
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1224
check_prev_add kernel/locking/lockdep.c:1866 [inline]
check_prevs_add kernel/locking/lockdep.c:1979 [inline]
validate_chain kernel/locking/lockdep.c:2350 [inline]
__lock_acquire+0x3014/0x4a30 kernel/locking/lockdep.c:3338
lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841
down_read+0x8d/0x120 kernel/locking/rwsem.c:24
do_user_addr_fault arch/x86/mm/fault.c:1426 [inline]
__do_page_fault+0x9c2/0xd60 arch/x86/mm/fault.c:1541
do_page_fault+0xe6/0x7d8 arch/x86/mm/fault.c:1572
page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:611 [inline]
RIP: 0010:iov_iter_fault_in_readable+0x377/0x450 lib/iov_iter.c:425
Code: 89 f6 41 88 57 e0 e8 38 d8 f3 fd 45 85 f6 74 c1 e9 70 fe ff ff e8 a9 d6 f3 fd 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 05 d8 f3 fd 85 db
RSP: 0018:ffff8880888d78a8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000020e90c3f
RDX: 0000000000000000 RSI: ffffffff838dbfc7 RDI: 0000000000000007
RBP: ffff8880888d7948 R08: ffff88808e4b0640 R09: fffff9400041f2ef
R10: fffff9400041f2ee R11: ffffea00020f9777 R12: 0000000000001000
R13: 0000000000001000 R14: 0000000000000000 R15: ffff8880888d7920
generic_perform_write+0x202/0x6b0 mm/filemap.c:3198
__generic_file_write_iter+0x25e/0x630 mm/filemap.c:3333
generic_file_write_iter+0x34e/0x6a0 mm/filemap.c:3361
call_write_iter include/linux/fs.h:1862 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x764/0xb40 fs/read_write.c:487
vfs_write+0x20c/0x580 fs/read_write.c:549
ksys_write+0x105/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446359
Code: e8 2c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f676804eda8 EFLAGS: 00000297 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006dac28 RCX: 0000000000446359
RDX: 00000000fffffe43 RSI: 0000000020000c40 RDI: 0000000000000004
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 00000000006dac2c
R13: 3ed592df9946286b R14: dfdd4f11168a8b2b R15: 00000000006dad2c