====================================================== WARNING: possible circular locking dependency detected 4.14.151+ #0 Not tainted ------------------------------------------------------ syz-executor.4/10666 is trying to acquire lock: (&mm->mmap_sem){++++}, at: [<0000000024b1ec27>] __do_page_fault+0x8a4/0xbb0 arch/x86/mm/fault.c:1356 but task is already holding lock: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000f93668f9>] inode_lock include/linux/fs.h:724 [inline] (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000f93668f9>] generic_file_write_iter+0x99/0x650 mm/filemap.c:3282 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:724 [inline] shmem_fallocate+0x150/0xae0 mm/shmem.c:2904 ashmem_shrink_scan drivers/staging/android/ashmem.c:453 [inline] ashmem_shrink_scan+0x1ca/0x4f0 drivers/staging/android/ashmem.c:437 ashmem_ioctl+0x2b4/0xd20 drivers/staging/android/ashmem.c:795 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 ashmem_mmap+0x4c/0x450 drivers/staging/android/ashmem.c:369 call_mmap include/linux/fs.h:1803 [inline] mmap_region+0x7d9/0xfb0 mm/mmap.c:1736 do_mmap+0x548/0xb80 mm/mmap.c:1512 do_mmap_pgoff include/linux/mm.h:2220 [inline] vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1564 [inline] SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1520 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&mm->mmap_sem){++++}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 down_read+0x37/0xa0 kernel/locking/rwsem.c:24 __do_page_fault+0x8a4/0xbb0 arch/x86/mm/fault.c:1356 page_fault+0x22/0x50 arch/x86/entry/entry_64.S:1122 fault_in_pages_readable include/linux/pagemap.h:614 [inline] iov_iter_fault_in_readable+0x29c/0x350 lib/iov_iter.c:421 generic_perform_write+0x158/0x460 mm/filemap.c:3122 __generic_file_write_iter+0x32e/0x550 mm/filemap.c:3257 generic_file_write_iter+0x36f/0x650 mm/filemap.c:3285 call_write_iter include/linux/fs.h:1798 [inline] do_iter_readv_writev+0x379/0x580 fs/read_write.c:679 do_iter_write fs/read_write.c:958 [inline] do_iter_write+0x152/0x550 fs/read_write.c:939 vfs_writev+0x146/0x2d0 fs/read_write.c:1003 do_pwritev+0x189/0x230 fs/read_write.c:1092 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#10); lock(ashmem_mutex); lock(&sb->s_type->i_mutex_key#10); lock(&mm->mmap_sem); *** DEADLOCK *** 2 locks held by syz-executor.4/10666: #0: (sb_writers#6){.+.+}, at: [<00000000580a18b7>] file_start_write include/linux/fs.h:2746 [inline] #0: (sb_writers#6){.+.+}, at: [<00000000580a18b7>] vfs_writev+0x240/0x2d0 fs/read_write.c:1002 #1: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000f93668f9>] inode_lock include/linux/fs.h:724 [inline] #1: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<00000000f93668f9>] generic_file_write_iter+0x99/0x650 mm/filemap.c:3282 stack backtrace: CPU: 0 PID: 10666 Comm: syz-executor.4 Not tainted 4.14.151+ #0 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xca/0x134 lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 down_read+0x37/0xa0 kernel/locking/rwsem.c:24 __do_page_fault+0x8a4/0xbb0 arch/x86/mm/fault.c:1356 page_fault+0x22/0x50 arch/x86/entry/entry_64.S:1122 RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:614 [inline] RIP: 0010:iov_iter_fault_in_readable+0x29c/0x350 lib/iov_iter.c:421 RSP: 0018:ffff8881b43bf8d8 EFLAGS: 00010212 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00000000000074f2 RDX: ffffffff81bac256 RSI: ffffc900000b2000 RDI: ffff8881b43bfd68 RBP: 1ffff11036877f1c R08: 0000000000001000 R09: fffff94000bd913c R10: fffff94000bd913b R11: ffffea0005ec89df R12: 0000000000001000 R13: 0000000000000000 R14: 0000000020008a3a R15: ffff8881b43bfd60 generic_perform_write+0x158/0x460 mm/filemap.c:3122 __generic_file_write_iter+0x32e/0x550 mm/filemap.c:3257 generic_file_write_iter+0x36f/0x650 mm/filemap.c:3285 call_write_iter include/linux/fs.h:1798 [inline] do_iter_readv_writev+0x379/0x580 fs/read_write.c:679 do_iter_write fs/read_write.c:958 [inline] do_iter_write+0x152/0x550 fs/read_write.c:939 vfs_writev+0x146/0x2d0 fs/read_write.c:1003 do_pwritev+0x189/0x230 fs/read_write.c:1092 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45a219 RSP: 002b:00007f88ea9d8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219 RDX: 0000000000000001 RSI: 0000000020000340 RDI: 0000000000000006 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000081805 R11: 0000000000000246 R12: 00007f88ea9d96d4 R13: 00000000004c7b90 R14: 00000000004ddba0 R15: 00000000ffffffff