====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc3-syzkaller #0 Not tainted ------------------------------------------------------ khugepaged/1143 is trying to acquire lock: ffff888096e9e248 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock include/linux/fs.h:791 [inline] ffff888096e9e248 (&sb->s_type->i_mutex_key#13){+.+.}, at: shmem_fallocate+0x15a/0xd40 mm/shmem.c:2736 but task is already holding lock: ffffffff89c510e0 (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part.0+0x0/0x30 include/linux/uaccess.h:173 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}: __fs_reclaim_acquire mm/page_alloc.c:4073 [inline] fs_reclaim_acquire.part.0+0x24/0x30 mm/page_alloc.c:4084 fs_reclaim_acquire mm/page_alloc.c:4670 [inline] prepare_alloc_pages mm/page_alloc.c:4667 [inline] __alloc_pages_nodemask+0x52d/0x910 mm/page_alloc.c:4719 alloc_pages_vma+0xdd/0x620 mm/mempolicy.c:2174 shmem_alloc_page+0xc0/0x180 mm/shmem.c:1499 shmem_alloc_and_acct_page+0x165/0x990 mm/shmem.c:1524 shmem_getpage_gfp+0x56d/0x29b0 mm/shmem.c:1838 shmem_getpage mm/shmem.c:154 [inline] shmem_write_begin+0x105/0x1e0 mm/shmem.c:2488 generic_perform_write+0x23b/0x540 mm/filemap.c:3287 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3416 generic_file_write_iter+0x420/0x68e mm/filemap.c:3448 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sb->s_type->i_mutex_key#13){+.+.}: check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3954 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4484 down_write+0x93/0x150 kernel/locking/rwsem.c:1534 inode_lock include/linux/fs.h:791 [inline] shmem_fallocate+0x15a/0xd40 mm/shmem.c:2736 ashmem_shrink_scan drivers/staging/android/ashmem.c:490 [inline] ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:465 do_shrink_slab+0x40f/0xad0 mm/vmscan.c:512 shrink_slab mm/vmscan.c:673 [inline] shrink_slab+0x19a/0x680 mm/vmscan.c:646 shrink_node_memcgs mm/vmscan.c:2676 [inline] shrink_node+0x46a/0x1ad0 mm/vmscan.c:2780 shrink_zones mm/vmscan.c:2983 [inline] do_try_to_free_pages+0x3ba/0x14f0 mm/vmscan.c:3036 try_to_free_pages+0x2dc/0x970 mm/vmscan.c:3275 __perform_reclaim mm/page_alloc.c:4113 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4134 [inline] __alloc_pages_slowpath+0x97e/0x2900 mm/page_alloc.c:4537 __alloc_pages_nodemask+0x646/0x910 mm/page_alloc.c:4751 __alloc_pages include/linux/gfp.h:496 [inline] __alloc_pages_node include/linux/gfp.h:509 [inline] khugepaged_alloc_page+0xa7/0x170 mm/khugepaged.c:785 collapse_huge_page+0x13e/0x41f0 mm/khugepaged.c:974 khugepaged_scan_pmd mm/khugepaged.c:1232 [inline] khugepaged_scan_mm_slot mm/khugepaged.c:2002 [inline] khugepaged_do_scan mm/khugepaged.c:2083 [inline] khugepaged+0x3604/0x44e0 mm/khugepaged.c:2128 kthread+0x361/0x430 kernel/kthread.c:255 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#13); lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#13); *** DEADLOCK *** 2 locks held by khugepaged/1143: #0: ffffffff89c510e0 (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part.0+0x0/0x30 include/linux/uaccess.h:173 #1: ffffffff89c2c788 (shrinker_rwsem){++++}, at: shrink_slab mm/vmscan.c:663 [inline] #1: ffffffff89c2c788 (shrinker_rwsem){++++}, at: shrink_slab+0xe6/0x680 mm/vmscan.c:646 stack backtrace: CPU: 0 PID: 1143 Comm: khugepaged Not tainted 5.6.0-rc3-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+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1684 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1808 check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3954 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4484 down_write+0x93/0x150 kernel/locking/rwsem.c:1534 inode_lock include/linux/fs.h:791 [inline] shmem_fallocate+0x15a/0xd40 mm/shmem.c:2736 ashmem_shrink_scan drivers/staging/android/ashmem.c:490 [inline] ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:465 do_shrink_slab+0x40f/0xad0 mm/vmscan.c:512 shrink_slab mm/vmscan.c:673 [inline] shrink_slab+0x19a/0x680 mm/vmscan.c:646 shrink_node_memcgs mm/vmscan.c:2676 [inline] shrink_node+0x46a/0x1ad0 mm/vmscan.c:2780 shrink_zones mm/vmscan.c:2983 [inline] do_try_to_free_pages+0x3ba/0x14f0 mm/vmscan.c:3036 try_to_free_pages+0x2dc/0x970 mm/vmscan.c:3275 __perform_reclaim mm/page_alloc.c:4113 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4134 [inline] __alloc_pages_slowpath+0x97e/0x2900 mm/page_alloc.c:4537 __alloc_pages_nodemask+0x646/0x910 mm/page_alloc.c:4751 __alloc_pages include/linux/gfp.h:496 [inline] __alloc_pages_node include/linux/gfp.h:509 [inline] khugepaged_alloc_page+0xa7/0x170 mm/khugepaged.c:785 collapse_huge_page+0x13e/0x41f0 mm/khugepaged.c:974 khugepaged_scan_pmd mm/khugepaged.c:1232 [inline] khugepaged_scan_mm_slot mm/khugepaged.c:2002 [inline] khugepaged_do_scan mm/khugepaged.c:2083 [inline] khugepaged+0x3604/0x44e0 mm/khugepaged.c:2128 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352