random: sshd: uninitialized urandom read (32 bytes read, 110 bits of entropy available)
random: sshd: uninitialized urandom read (32 bytes read, 115 bits of entropy available)
IPVS: Creating netns size=2552 id=1

======================================================
[ INFO: possible circular locking dependency detected ]
4.4.119-g855ea74 #28 Not tainted
-------------------------------------------------------
syz-executor0/3807 is trying to acquire lock:
 (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<ffffffff81463321>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816

but task is already holding lock:
 (ashmem_mutex){+.+.+.}, at: [<ffffffff82c61e36>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff8376a07b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8376a07b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
       [<ffffffff82c61283>] ashmem_mmap+0x53/0x400 drivers/staging/android/ashmem.c:366
       [<ffffffff814b0e0f>] mmap_region+0x94f/0x1250 mm/mmap.c:1664
       [<ffffffff814b1c0d>] do_mmap+0x4fd/0x9d0 mm/mmap.c:1441
       [<ffffffff8147008e>] do_mmap_pgoff include/linux/mm.h:1915 [inline]
       [<ffffffff8147008e>] vm_mmap_pgoff+0x16e/0x1c0 mm/util.c:296
       [<ffffffff814afddf>] SYSC_mmap_pgoff mm/mmap.c:1491 [inline]
       [<ffffffff814afddf>] SyS_mmap_pgoff+0x33f/0x560 mm/mmap.c:1449
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff83774fea>] sysenter_flags_fixed+0xd/0x17

       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff814956aa>] __might_fault+0x14a/0x1d0 mm/memory.c:3810
       [<ffffffff8155aac2>] copy_to_user arch/x86/include/asm/uaccess.h:760 [inline]
       [<ffffffff8155aac2>] filldir+0x162/0x2d0 fs/readdir.c:180
       [<ffffffff815981ae>] dir_emit_dot include/linux/fs.h:3070 [inline]
       [<ffffffff815981ae>] dir_emit_dots include/linux/fs.h:3081 [inline]
       [<ffffffff815981ae>] dcache_readdir+0x11e/0x7b0 fs/libfs.c:150
       [<ffffffff8155a708>] iterate_dir+0x1c8/0x420 fs/readdir.c:42
       [<ffffffff8155b3fa>] SYSC_getdents fs/readdir.c:215 [inline]
       [<ffffffff8155b3fa>] SyS_getdents+0x14a/0x270 fs/readdir.c:196
       [<ffffffff8377365f>] entry_SYSCALL_64_fastpath+0x1c/0x98

       [<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
       [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
       [<ffffffff8376a07b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff8376a07b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
       [<ffffffff81463321>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
       [<ffffffff8151c722>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
       [<ffffffff82c61ec7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
       [<ffffffff8151e69b>] vfs_llseek fs/read_write.c:260 [inline]
       [<ffffffff8151e69b>] SYSC_lseek fs/read_write.c:285 [inline]
       [<ffffffff8151e69b>] SyS_lseek fs/read_write.c:276 [inline]
       [<ffffffff8151e69b>] C_SYSC_lseek fs/read_write.c:297 [inline]
       [<ffffffff8151e69b>] compat_SyS_lseek+0xeb/0x170 fs/read_write.c:295
       [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
       [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
       [<ffffffff83774fea>] sysenter_flags_fixed+0xd/0x17

other info that might help us debug this:

Chain exists of:
 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz-executor0/3807:
 #0:  (ashmem_mutex){+.+.+.}, at: [<ffffffff82c61e36>] ashmem_llseek+0x56/0x1f0 drivers/staging/android/ashmem.c:330

stack backtrace:
CPU: 1 PID: 3807 Comm: syz-executor0 Not tainted 4.4.119-g855ea74 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 7b61b7e5bd8cbb17 ffff8801c5757a58 ffffffff81d0402d
 ffffffff851a0010 ffffffff851a9b50 ffffffff851bee80 ffff8801d8c150f8
 ffff8801d8c14800 ffff8801c5757aa0 ffffffff81233ba1 ffff8801d8c150f8
Call Trace:
 [<ffffffff81d0402d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0402d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81233ba1>] print_circular_bug+0x271/0x310 kernel/locking/lockdep.c:1226
 [<ffffffff8123ab2f>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff8123ab2f>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff8123ab2f>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff8123ab2f>] __lock_acquire+0x371f/0x4b50 kernel/locking/lockdep.c:3213
 [<ffffffff8123d7ce>] lock_acquire+0x15e/0x460 kernel/locking/lockdep.c:3592
 [<ffffffff8376a07b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff8376a07b>] mutex_lock_nested+0xbb/0x850 kernel/locking/mutex.c:621
 [<ffffffff81463321>] shmem_file_llseek+0xf1/0x240 mm/shmem.c:1816
 [<ffffffff8151c722>] vfs_llseek+0xa2/0xd0 fs/read_write.c:260
 [<ffffffff82c61ec7>] ashmem_llseek+0xe7/0x1f0 drivers/staging/android/ashmem.c:342
 [<ffffffff8151e69b>] vfs_llseek fs/read_write.c:260 [inline]
 [<ffffffff8151e69b>] SYSC_lseek fs/read_write.c:285 [inline]
 [<ffffffff8151e69b>] SyS_lseek fs/read_write.c:276 [inline]
 [<ffffffff8151e69b>] C_SYSC_lseek fs/read_write.c:297 [inline]
 [<ffffffff8151e69b>] compat_SyS_lseek+0xeb/0x170 fs/read_write.c:295
 [<ffffffff81006d91>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d91>] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459
 [<ffffffff83774fea>] sys