====================================================== WARNING: possible circular locking dependency detected 5.7.0-rc2-syzkaller #0 Not tainted ------------------------------------------------------ khugepaged/1146 is trying to acquire lock: ffff88803f4088d0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:797 [inline] ffff88803f4088d0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}, at: shmem_fallocate+0xef/0xdb0 mm/shmem.c:2734 but task is already holding lock: ffffffff893175b0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:3797 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 __fs_reclaim_acquire+0x20/0x30 mm/page_alloc.c:4142 fs_reclaim_acquire mm/page_alloc.c:4153 [inline] prepare_alloc_pages+0x21d/0x4a0 mm/page_alloc.c:4739 __alloc_pages_nodemask+0xbc/0x5e0 mm/page_alloc.c:4791 alloc_pages_vma+0x4dd/0xd10 mm/mempolicy.c:2258 shmem_alloc_page mm/shmem.c:1486 [inline] shmem_alloc_and_acct_page+0x40e/0xbe0 mm/shmem.c:1511 shmem_getpage_gfp+0x1580/0x3120 mm/shmem.c:1828 shmem_getpage mm/shmem.c:154 [inline] shmem_write_begin+0xcd/0x1a0 mm/shmem.c:2486 generic_perform_write+0x23b/0x4e0 mm/filemap.c:3302 __generic_file_write_iter+0x22b/0x4e0 mm/filemap.c:3431 generic_file_write_iter+0x4a6/0x650 mm/filemap.c:3463 call_write_iter include/linux/fs.h:1907 [inline] new_sync_write fs/read_write.c:484 [inline] __vfs_write+0x54c/0x710 fs/read_write.c:497 vfs_write+0x274/0x580 fs/read_write.c:559 ksys_write+0x11b/0x220 fs/read_write.c:612 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2c30 kernel/locking/lockdep.c:4355 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 down_write+0x55/0x130 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:797 [inline] shmem_fallocate+0xef/0xdb0 mm/shmem.c:2734 ashmem_shrink_scan+0x367/0x4a0 drivers/staging/android/ashmem.c:490 do_shrink_slab+0x36f/0x5c0 mm/vmscan.c:512 shrink_slab+0x188/0x2b0 mm/vmscan.c:673 shrink_node_memcgs+0x414/0x5e0 mm/vmscan.c:2673 shrink_node+0xb66/0x19c0 mm/vmscan.c:2777 shrink_zones+0x27c/0x8d0 mm/vmscan.c:2980 do_try_to_free_pages+0x229/0xc30 mm/vmscan.c:3033 try_to_free_pages+0x328/0xb60 mm/vmscan.c:3272 __perform_reclaim mm/page_alloc.c:4182 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4203 [inline] __alloc_pages_slowpath+0xe72/0x2290 mm/page_alloc.c:4609 __alloc_pages_nodemask+0x3c2/0x5e0 mm/page_alloc.c:4822 __alloc_pages include/linux/gfp.h:504 [inline] __alloc_pages_node include/linux/gfp.h:517 [inline] khugepaged_alloc_page+0xd2/0x180 mm/khugepaged.c:782 collapse_huge_page mm/khugepaged.c:971 [inline] khugepaged_scan_pmd mm/khugepaged.c:1251 [inline] khugepaged_scan_mm_slot+0x1a9b/0x63c0 mm/khugepaged.c:2019 khugepaged_do_scan+0x22f/0x590 mm/khugepaged.c:2100 khugepaged+0xa5/0x7b0 mm/khugepaged.c:2145 kthread+0x353/0x380 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#16); lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#16); *** DEADLOCK *** 2 locks held by khugepaged/1146: #0: ffffffff893175b0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:3797 #1: ffffffff8930f510 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xa8/0x2b0 mm/vmscan.c:663 stack backtrace: CPU: 1 PID: 1146 Comm: khugepaged Not tainted 5.7.0-rc2-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+0x1e9/0x30e lib/dump_stack.c:118 print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1722 check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1846 check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2c30 kernel/locking/lockdep.c:4355 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4934 down_write+0x55/0x130 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:797 [inline] shmem_fallocate+0xef/0xdb0 mm/shmem.c:2734 ashmem_shrink_scan+0x367/0x4a0 drivers/staging/android/ashmem.c:490 do_shrink_slab+0x36f/0x5c0 mm/vmscan.c:512 shrink_slab+0x188/0x2b0 mm/vmscan.c:673 shrink_node_memcgs+0x414/0x5e0 mm/vmscan.c:2673 shrink_node+0xb66/0x19c0 mm/vmscan.c:2777 shrink_zones+0x27c/0x8d0 mm/vmscan.c:2980 do_try_to_free_pages+0x229/0xc30 mm/vmscan.c:3033 try_to_free_pages+0x328/0xb60 mm/vmscan.c:3272 __perform_reclaim mm/page_alloc.c:4182 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4203 [inline] __alloc_pages_slowpath+0xe72/0x2290 mm/page_alloc.c:4609 __alloc_pages_nodemask+0x3c2/0x5e0 mm/page_alloc.c:4822 __alloc_pages include/linux/gfp.h:504 [inline] __alloc_pages_node include/linux/gfp.h:517 [inline] khugepaged_alloc_page+0xd2/0x180 mm/khugepaged.c:782 collapse_huge_page mm/khugepaged.c:971 [inline] khugepaged_scan_pmd mm/khugepaged.c:1251 [inline] khugepaged_scan_mm_slot+0x1a9b/0x63c0 mm/khugepaged.c:2019 khugepaged_do_scan+0x22f/0x590 mm/khugepaged.c:2100 khugepaged+0xa5/0x7b0 mm/khugepaged.c:2145 kthread+0x353/0x380 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352