syzbot


possible deadlock in ext4_xattr_inode_lookup_create

Status: upstream: reported C repro on 2024/11/04 12:41
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+aa8811dc2a41ca80316e@syzkaller.appspotmail.com
First crash: 28d, last: 28d
Bug presence (1)
Date Name Commit Repro Result
2024/11/07 upstream (ToT) ff7afaeca1a1 C [report] possible deadlock in ext4_xattr_inode_lookup_create
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_xattr_inode_lookup_create ext4 C done 28 6d19h 65d 0/28 upstream: reported C repro on 2024/09/28 07:43

Sample crash report:
EXT4-fs (loop0): encrypted files will use data=ordered instead of data journaling mode
EXT4-fs (loop0): 1 truncate cleaned up
======================================================
WARNING: possible circular locking dependency detected
6.1.115-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor193/4373 is trying to acquire lock:
ffff888071bbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff888071bbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: ext4_xattr_inode_create fs/ext4/xattr.c:1465 [inline]
ffff888071bbb628 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: ext4_xattr_inode_lookup_create+0x1a21/0x1ef0 fs/ext4/xattr.c:1547

but task is already holding lock:
ffff888071bbe6d8 (&ei->i_data_sem/3){++++}-{3:3}, at: ext4_setattr+0x13fa/0x1a00 fs/ext4/inode.c:5564

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ei->i_data_sem/3){++++}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ext4_update_i_disksize fs/ext4/ext4.h:3377 [inline]
       ext4_xattr_inode_write fs/ext4/xattr.c:1403 [inline]
       ext4_xattr_inode_lookup_create+0x16ac/0x1ef0 fs/ext4/xattr.c:1553
       ext4_xattr_ibody_set+0x210/0x720 fs/ext4/xattr.c:2215
       ext4_xattr_set_handle+0xc72/0x1560 fs/ext4/xattr.c:2392
       ext4_xattr_set+0x26e/0x3d0 fs/ext4/xattr.c:2506
       __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
       __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
       vfs_setxattr+0x21d/0x420 fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr+0x250/0x2b0 fs/xattr.c:617
       path_setxattr+0x1bc/0x2a0 fs/xattr.c:636
       __do_sys_lsetxattr fs/xattr.c:659 [inline]
       __se_sys_lsetxattr fs/xattr.c:655 [inline]
       __x64_sys_lsetxattr+0xb4/0xd0 fs/xattr.c:655
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:758 [inline]
       ext4_xattr_inode_create fs/ext4/xattr.c:1465 [inline]
       ext4_xattr_inode_lookup_create+0x1a21/0x1ef0 fs/ext4/xattr.c:1547
       ext4_xattr_block_set+0x2a1/0x3920 fs/ext4/xattr.c:1867
       ext4_xattr_move_to_block fs/ext4/xattr.c:2616 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2691 [inline]
       ext4_expand_extra_isize_ea+0x10d5/0x1bb0 fs/ext4/xattr.c:2783
       __ext4_expand_extra_isize+0x2f7/0x3d0 fs/ext4/inode.c:5936
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5979 [inline]
       __ext4_mark_inode_dirty+0x54f/0x920 fs/ext4/inode.c:6057
       ext4_setattr+0x1493/0x1a00 fs/ext4/inode.c:5567
       notify_change+0xce3/0xfc0 fs/attr.c:499
       do_truncate+0x21c/0x300 fs/open.c:65
       handle_truncate fs/namei.c:3285 [inline]
       do_open fs/namei.c:3630 [inline]
       path_openat+0x27e2/0x2e60 fs/namei.c:3783
       do_filp_open+0x230/0x480 fs/namei.c:3810
       do_sys_openat2+0x13b/0x4f0 fs/open.c:1318
       do_sys_open fs/open.c:1334 [inline]
       __do_sys_creat fs/open.c:1412 [inline]
       __se_sys_creat fs/open.c:1406 [inline]
       __x64_sys_creat+0x11f/0x160 fs/open.c:1406
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->i_data_sem/3);
                               lock(&ea_inode->i_rwsem#8/1);
                               lock(&ei->i_data_sem/3);
  lock(&ea_inode->i_rwsem#8/1);

 *** DEADLOCK ***

5 locks held by syz-executor193/4373:
 #0: ffff88807c67c460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
 #1: ffff888071bbe850 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888071bbe850 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: do_truncate+0x208/0x300 fs/open.c:63
 #2: ffff888071bbe9f0 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:803 [inline]
 #2: ffff888071bbe9f0 (mapping.invalidate_lock){++++}-{3:3}, at: ext4_setattr+0xec7/0x1a00 fs/ext4/inode.c:5524
 #3: ffff888071bbe6d8 (&ei->i_data_sem/3){++++}-{3:3}, at: ext4_setattr+0x13fa/0x1a00 fs/ext4/inode.c:5564
 #4: ffff888071bbe518 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_trylock_xattr fs/ext4/xattr.h:162 [inline]
 #4: ffff888071bbe518 (&ei->xattr_sem){++++}-{3:3}, at: ext4_try_to_expand_extra_isize fs/ext4/inode.c:5976 [inline]
 #4: ffff888071bbe518 (&ei->xattr_sem){++++}-{3:3}, at: __ext4_mark_inode_dirty+0x4b0/0x920 fs/ext4/inode.c:6057

stack backtrace:
CPU: 1 PID: 4373 Comm: syz-executor193 Not tainted 6.1.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 down_write+0x36/0x60 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:758 [inline]
 ext4_xattr_inode_create fs/ext4/xattr.c:1465 [inline]
 ext4_xattr_inode_lookup_create+0x1a21/0x1ef0 fs/ext4/xattr.c:1547
 ext4_xattr_block_set+0x2a1/0x3920 fs/ext4/xattr.c:1867
 ext4_xattr_move_to_block fs/ext4/xattr.c:2616 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2691 [inline]
 ext4_expand_extra_isize_ea+0x10d5/0x1bb0 fs/ext4/xattr.c:2783
 __ext4_expand_extra_isize+0x2f7/0x3d0 fs/ext4/inode.c:5936
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5979 [inline]
 __ext4_mark_inode_dirty+0x54f/0x920 fs/ext4/inode.c:6057
 ext4_setattr+0x1493/0x1a00 fs/ext4/inode.c:5567
 notify_change+0xce3/0xfc0 fs/attr.c:499
 do_truncate+0x21c/0x300 fs/open.c:65
 handle_truncate fs/namei.c:3285 [inline]
 do_open fs/namei.c:3630 [inline]
 path_openat+0x27e2/0x2e60 fs/namei.c:3783
 do_filp_open+0x230/0x480 fs/namei.c:3810
 do_sys_openat2+0x13b/0x4f0 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_creat fs/open.c:1412 [inline]
 __se_sys_creat fs/open.c:1406 [inline]
 __x64_sys_creat+0x11f/0x160 fs/open.c:1406
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1dc5e67269
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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:00007ffe18693a18 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f1dc5e67269
RDX: 00007f1dc5e67269 RSI: 000000000000013d RDI: 0000000020000140
RBP: 0000000000000000 R08: 00007ffe18693a50 R09: 00007ffe18693a50
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe18693a3c
R13: 000000000000003e R14: 431bde82d7b634db R15: 00007ffe18693a70
 </TASK>

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/11/04 13:46 linux-6.1.y 7c15117f9468 f00eed24 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:11 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:10 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:09 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:06 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:04 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:03 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:00 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 13:00 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:57 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:55 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:53 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:51 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:43 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
2024/11/04 12:40 linux-6.1.y 7c15117f9468 f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_xattr_inode_lookup_create
* Struck through repros no longer work on HEAD.