syzbot


possible deadlock in nilfs_transaction_begin

Status: upstream: reported on 2024/05/18 12:29
Subsystems: nilfs
[Documentation on labels]
Reported-by: syzbot+77c39f023a0cb2e4c149@syzkaller.appspotmail.com
First crash: 35d, last: 1d15h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [nilfs?] possible deadlock in nilfs_transaction_begin 1 (2) 2024/05/18 19:16

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
syz-executor.1/6047 is trying to acquire lock:
ffffffff8dd3aac0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:334 [inline]
ffffffff8dd3aac0 (fs_reclaim){+.+.}-{0:0}, at: prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4449

but task is already holding lock:
ffff88802b0b22a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&nilfs->ns_segctor_sem){++++}-{3:3}:
       down_read+0x9a/0x330 kernel/locking/rwsem.c:1526
       nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223
       nilfs_create+0xb7/0x320 fs/nilfs2/namei.c:82
       lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3505
       open_last_lookups fs/namei.c:3574 [inline]
       path_openat+0x92f/0x29f0 fs/namei.c:3804
       do_filp_open+0x1dc/0x430 fs/namei.c:3834
       do_sys_openat2+0x17a/0x1e0 fs/open.c:1405
       do_sys_open fs/open.c:1420 [inline]
       __do_compat_sys_open fs/open.c:1471 [inline]
       __se_compat_sys_open fs/open.c:1469 [inline]
       __ia32_compat_sys_open+0x147/0x1e0 fs/open.c:1469
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #1 (sb_internal#2){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1655 [inline]
       sb_start_intwrite include/linux/fs.h:1838 [inline]
       nilfs_transaction_begin+0x21b/0xa40 fs/nilfs2/segment.c:220
       nilfs_dirty_inode+0x1a4/0x270 fs/nilfs2/inode.c:1153
       __mark_inode_dirty+0x1f0/0xe70 fs/fs-writeback.c:2486
       mark_inode_dirty_sync include/linux/fs.h:2409 [inline]
       iput.part.0+0x5b/0x7f0 fs/inode.c:1764
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       shrink_kill fs/dcache.c:1048 [inline]
       shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
       super_cache_scan+0x32a/0x550 fs/super.c:221
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4790
       shrink_many mm/vmscan.c:4851 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951
       shrink_node mm/vmscan.c:5910 [inline]
       kswapd_shrink_node mm/vmscan.c:6720 [inline]
       balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7180
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
       might_alloc include/linux/sched/mm.h:334 [inline]
       prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4449
       __alloc_pages_noprof+0x194/0x2460 mm/page_alloc.c:4667
       alloc_pages_mpol_noprof+0x275/0x610 mm/mempolicy.c:2265
       folio_alloc_noprof+0x1e/0xc0 mm/mempolicy.c:2343
       filemap_alloc_folio_noprof+0x3ba/0x490 mm/filemap.c:1008
       __filemap_get_folio+0x51e/0xa80 mm/filemap.c:1950
       pagecache_get_page+0x2c/0x250 mm/folio-compat.c:87
       block_write_begin+0x38/0x4a0 fs/buffer.c:2232
       nilfs_write_begin+0x9f/0x1a0 fs/nilfs2/inode.c:262
       page_symlink+0x356/0x450 fs/namei.c:5236
       nilfs_symlink+0x23c/0x3c0 fs/nilfs2/namei.c:153
       vfs_symlink fs/namei.c:4489 [inline]
       vfs_symlink+0x3e8/0x660 fs/namei.c:4473
       do_symlinkat+0x263/0x310 fs/namei.c:4515
       __do_sys_symlink fs/namei.c:4536 [inline]
       __se_sys_symlink fs/namei.c:4534 [inline]
       __ia32_sys_symlink+0x78/0xa0 fs/namei.c:4534
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

other info that might help us debug this:

Chain exists of:
  fs_reclaim
 --> sb_internal#2 --> &nilfs->ns_segctor_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&nilfs->ns_segctor_sem);
                               lock(sb_internal#2);
                               lock(&nilfs->ns_segctor_sem);
  lock(fs_reclaim);

 *** DEADLOCK ***

4 locks held by syz-executor.1/6047:
 #0: ffff888021bb2420 (sb_writers#12){.+.+}-{0:0}, at: filename_create+0x10d/0x530 fs/namei.c:3893
 #1: ffff888062a5a918 (&type->i_mutex_dir_key#8/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:826 [inline]
 #1: ffff888062a5a918 (&type->i_mutex_dir_key#8/1){+.+.}-{3:3}, at: filename_create+0x1c2/0x530 fs/namei.c:3900
 #2: ffff888021bb2610 (sb_internal#2){.+.+}-{0:0}, at: nilfs_symlink+0x114/0x3c0 fs/nilfs2/namei.c:140
 #3: ffff88802b0b22a0 (&nilfs->ns_segctor_sem){++++}-{3:3}
, at: nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223

stack backtrace:
CPU: 2 PID: 6047 Comm: syz-executor.1 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
 fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
 might_alloc include/linux/sched/mm.h:334 [inline]
 prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4449
 __alloc_pages_noprof+0x194/0x2460 mm/page_alloc.c:4667
 alloc_pages_mpol_noprof+0x275/0x610 mm/mempolicy.c:2265
 folio_alloc_noprof+0x1e/0xc0 mm/mempolicy.c:2343
 filemap_alloc_folio_noprof+0x3ba/0x490 mm/filemap.c:1008
 __filemap_get_folio+0x51e/0xa80 mm/filemap.c:1950
 pagecache_get_page+0x2c/0x250 mm/folio-compat.c:87
 block_write_begin+0x38/0x4a0 fs/buffer.c:2232
 nilfs_write_begin+0x9f/0x1a0 fs/nilfs2/inode.c:262
 page_symlink+0x356/0x450 fs/namei.c:5236
 nilfs_symlink+0x23c/0x3c0 fs/nilfs2/namei.c:153
 vfs_symlink fs/namei.c:4489 [inline]
 vfs_symlink+0x3e8/0x660 fs/namei.c:4473
 do_symlinkat+0x263/0x310 fs/namei.c:4515
 __do_sys_symlink fs/namei.c:4536 [inline]
 __se_sys_symlink fs/namei.c:4534 [inline]
 __ia32_sys_symlink+0x78/0xa0 fs/namei.c:4534
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7270579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e415ac EFLAGS: 00000292 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 0000000020000680 RCX: 0000000020000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
syz-executor.1: attempt to access beyond end of device
loop1: rw=0, sector=24, nr_sectors = 2 limit=0
NILFS (loop1): I/O error reading meta-data file (ino=3, block-offset=0)
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/16 22:26 upstream 2ccbdf43d5e7 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/06/16 20:25 upstream 2ccbdf43d5e7 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/06/11 19:13 upstream 83a7eefedc9b c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/06/11 12:22 upstream 83a7eefedc9b c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/27 17:13 upstream 2bfcfd584ff5 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/25 15:38 upstream 56fb6f92854f c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/23 16:22 upstream c760b3725e52 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/20 19:14 upstream 6e51b4b5bbc0 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/20 19:14 upstream 6e51b4b5bbc0 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/20 13:09 upstream eb6a9339efeb c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/20 12:43 upstream eb6a9339efeb c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/19 11:10 upstream 0450d2083be6 c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
2024/05/14 12:21 upstream a5131c3fdf26 fdb4c10c .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 possible deadlock in nilfs_transaction_begin
* Struck through repros no longer work on HEAD.