====================================================== WARNING: possible circular locking dependency detected 5.8.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ kswapd0/1674 is trying to acquire lock: ffff88804b4e9610 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:800 [inline] ffff88804b4e9610 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: shmem_fallocate+0x153/0xd90 mm/shmem.c:2707 but task is already holding lock: ffffffff89c6c260 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:5016 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4183 [inline] fs_reclaim_acquire mm/page_alloc.c:4194 [inline] prepare_alloc_pages mm/page_alloc.c:4780 [inline] __alloc_pages_nodemask+0x3d1/0x930 mm/page_alloc.c:4832 alloc_pages_vma+0xdd/0x720 mm/mempolicy.c:2255 shmem_alloc_page+0x11f/0x1f0 mm/shmem.c:1502 shmem_alloc_and_acct_page+0x161/0x8a0 mm/shmem.c:1527 shmem_getpage_gfp+0x511/0x2450 mm/shmem.c:1823 shmem_getpage mm/shmem.c:153 [inline] shmem_write_begin+0xf9/0x1d0 mm/shmem.c:2459 generic_perform_write+0x20a/0x4f0 mm/filemap.c:3318 __generic_file_write_iter+0x24b/0x610 mm/filemap.c:3447 generic_file_write_iter+0x3a6/0x5c0 mm/filemap.c:3479 call_write_iter include/linux/fs.h:1908 [inline] new_sync_write+0x422/0x650 fs/read_write.c:503 vfs_write+0x59d/0x6b0 fs/read_write.c:578 ksys_write+0x12d/0x250 fs/read_write.c:631 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2acb/0x56e0 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:800 [inline] shmem_fallocate+0x153/0xd90 mm/shmem.c:2707 ashmem_shrink_scan.part.0+0x2e9/0x490 drivers/staging/android/ashmem.c:490 ashmem_shrink_scan+0x6c/0xa0 drivers/staging/android/ashmem.c:473 do_shrink_slab+0x3c6/0xab0 mm/vmscan.c:518 shrink_slab+0x16f/0x5c0 mm/vmscan.c:679 shrink_node_memcgs mm/vmscan.c:2658 [inline] shrink_node+0x519/0x1b60 mm/vmscan.c:2770 kswapd_shrink_node mm/vmscan.c:3517 [inline] balance_pgdat+0x72f/0x10d0 mm/vmscan.c:3675 kswapd+0x5a5/0xe70 mm/vmscan.c:3932 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#15); lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#15); *** DEADLOCK *** 2 locks held by kswapd0/1674: #0: ffffffff89c6c260 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:5016 #1: ffffffff89c46a90 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xc7/0x5c0 mm/vmscan.c:669 stack backtrace: CPU: 0 PID: 1674 Comm: kswapd0 Not tainted 5.8.0-rc5-syzkaller #0 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+0x18f/0x20d lib/dump_stack.c:118 check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827 check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2acb/0x56e0 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:800 [inline] shmem_fallocate+0x153/0xd90 mm/shmem.c:2707 ashmem_shrink_scan.part.0+0x2e9/0x490 drivers/staging/android/ashmem.c:490 ashmem_shrink_scan+0x6c/0xa0 drivers/staging/android/ashmem.c:473 do_shrink_slab+0x3c6/0xab0 mm/vmscan.c:518 shrink_slab+0x16f/0x5c0 mm/vmscan.c:679 shrink_node_memcgs mm/vmscan.c:2658 [inline] shrink_node+0x519/0x1b60 mm/vmscan.c:2770 kswapd_shrink_node mm/vmscan.c:3517 [inline] balance_pgdat+0x72f/0x10d0 mm/vmscan.c:3675 kswapd+0x5a5/0xe70 mm/vmscan.c:3932 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293