syzbot


possible deadlock in nilfs_bmap_clear

Status: upstream: reported on 2022/11/17 14:29
Reported-by: syzbot+4a885c3a7a60d6be3583@syzkaller.appspotmail.com
First crash: 9d11h, last: 9d11h

Sample crash report:
============================================
WARNING: possible recursive locking detected
6.1.0-rc5-syzkaller-00044-gcc675d22e422 #0 Not tainted
--------------------------------------------
syz-executor.4/18478 is trying to acquire lock:
ffff888076ad93f8 (&bmap->b_sem){++++}-{3:3}, at: nilfs_bmap_clear+0x25/0x90 fs/nilfs2/bmap.c:311

but task is already holding lock:
ffff88808d5900c0 (&bmap->b_sem){++++}-{3:3}, at: nilfs_bmap_insert+0x9d/0x390 fs/nilfs2/bmap.c:146

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&bmap->b_sem);
  lock(&bmap->b_sem);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

7 locks held by syz-executor.4/18478:
 #0: ffff8880824a0460 (sb_writers#30){.+.+}-{0:0}, at: do_sendfile+0x61c/0xfd0 fs/read_write.c:1254
 #1: ffff88808d5902a8 (&sb->s_type->i_mutex_key#37){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff88808d5902a8 (&sb->s_type->i_mutex_key#37){+.+.}-{3:3}, at: generic_file_write_iter+0x7f/0x310 mm/filemap.c:3910
 #2: ffff8880824a0650 (sb_internal#3){.+.+}-{0:0}, at: nilfs_write_begin+0x6c/0x110 fs/nilfs2/inode.c:256
 #3: ffff8880855592a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_begin+0x359/0x770 fs/nilfs2/segment.c:223
 #4: ffff88808d5900c0 (&bmap->b_sem){++++}-{3:3}, at: nilfs_bmap_insert+0x9d/0x390 fs/nilfs2/bmap.c:146
 #5: ffffffff8d3d0d10 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab_memcg+0xd9/0x630 mm/vmscan.c:884
 #6: ffff8880824a00e0 (&type->s_umount_key#106){++++}-{3:3}, at: trylock_super fs/super.c:415 [inline]
 #6: ffff8880824a00e0 (&type->s_umount_key#106){++++}-{3:3}, at: super_cache_scan+0x6a/0x470 fs/super.c:79

stack backtrace:
CPU: 1 PID: 18478 Comm: syz-executor.4 Not tainted 6.1.0-rc5-syzkaller-00044-gcc675d22e422 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2990 [inline]
 check_deadlock kernel/locking/lockdep.c:3033 [inline]
 validate_chain+0x4721/0x6470 kernel/locking/lockdep.c:3818
 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
 lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5668
 down_write+0x9c/0x270 kernel/locking/rwsem.c:1562
 nilfs_bmap_clear+0x25/0x90 fs/nilfs2/bmap.c:311
 nilfs_clear_inode+0x161/0x2c0 fs/nilfs2/inode.c:906
 nilfs_evict_inode+0xf9/0x3e0 fs/nilfs2/inode.c:925
 evict+0x2a4/0x620 fs/inode.c:664
 dispose_list fs/inode.c:697 [inline]
 prune_icache_sb+0x268/0x320 fs/inode.c:896
 super_cache_scan+0x362/0x470 fs/super.c:106
 do_shrink_slab+0x4e1/0xa00 mm/vmscan.c:842
 shrink_slab_memcg+0x2ec/0x630 mm/vmscan.c:911
 shrink_slab+0xbe/0x340 mm/vmscan.c:990
 shrink_node_memcgs+0x3c3/0x770 mm/vmscan.c:6076
 shrink_node+0x299/0x1050 mm/vmscan.c:6105
 shrink_zones+0x4fb/0xc40 mm/vmscan.c:6343
 do_try_to_free_pages+0x215/0xcd0 mm/vmscan.c:6405
 try_to_free_mem_cgroup_pages+0x3cb/0x6d0 mm/vmscan.c:6720
 reclaim_high+0x1f4/0x280 mm/memcontrol.c:2389
 mem_cgroup_handle_over_high+0x145/0x2b0 mm/memcontrol.c:2574
 try_charge_memcg+0xfed/0x11f0 mm/memcontrol.c:2812
 try_charge mm/memcontrol.c:2823 [inline]
 charge_memcg+0x132/0x620 mm/memcontrol.c:6879
 __mem_cgroup_charge+0x23/0x80 mm/memcontrol.c:6900
 mem_cgroup_charge include/linux/memcontrol.h:667 [inline]
 __filemap_add_folio+0x3f6/0x1a60 mm/filemap.c:852
 filemap_add_folio+0x12c/0x5c0 mm/filemap.c:934
 __filemap_get_folio+0x93c/0x1240 mm/filemap.c:1976
 pagecache_get_page+0x28/0x260 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:613 [inline]
 grab_cache_page include/linux/pagemap.h:743 [inline]
 nilfs_grab_buffer+0xab/0x550 fs/nilfs2/page.c:57
 nilfs_btnode_create_block+0x4b/0x340 fs/nilfs2/btnode.c:52
 nilfs_btree_get_new_block fs/nilfs2/btree.c:65 [inline]
 nilfs_btree_prepare_insert fs/nilfs2/btree.c:1130 [inline]
 nilfs_btree_insert+0xd22/0x1c30 fs/nilfs2/btree.c:1238
 nilfs_bmap_do_insert fs/nilfs2/bmap.c:121 [inline]
 nilfs_bmap_insert+0x23b/0x390 fs/nilfs2/bmap.c:147
 nilfs_get_block+0x423/0x8e0 fs/nilfs2/inode.c:101
 __block_write_begin_int+0x57c/0x1ae0 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x93/0x1e0 fs/buffer.c:2102
 nilfs_write_begin+0x9c/0x110 fs/nilfs2/inode.c:261
 generic_perform_write+0x314/0x610 mm/filemap.c:3753
 __generic_file_write_iter+0x29b/0x400 mm/filemap.c:3849
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3913
 do_iter_write+0x6f0/0xc50 fs/read_write.c:861
 iter_file_splice_write+0x830/0xff0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0xe6/0x1c0 fs/splice.c:931
 splice_direct_to_actor+0x4e4/0xc00 fs/splice.c:886
 do_splice_direct+0x2a0/0x3f0 fs/splice.c:974
 do_sendfile+0x641/0xfd0 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f74c308b639
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f74c3e97168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f74c31ac050 RCX: 00007f74c308b639
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00007f74c30e6ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000f03affff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe3045508f R14: 00007f74c3e97300 R15: 0000000000022000
 </TASK>

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2022/11/17 13:20 upstream cc675d22e422 3a127a31 .config log report info possible deadlock in nilfs_bmap_clear
* Struck through repros no longer work on HEAD.