syzbot


possible deadlock in ext4_xattr_inode_lookup_create

Status: upstream: reported C repro on 2024/09/28 07:43
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+d91a6e2efb07bd3354e9@syzkaller.appspotmail.com
First crash: 57d, last: 1d02h
Cause bisection: introduced by (bisect log) :
commit 1e9d62d252812575ded7c620d8fc67c32ff06c16
Author: Jun Nie <jun.nie@linaro.org>
Date: Tue Jan 3 01:45:16 2023 +0000

  ext4: optimize ea_inode block expansion

Crash: possible deadlock in ext4_xattr_inode_iget (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] possible deadlock in ext4_xattr_inode_lookup_create 0 (1) 2024/09/28 07:43
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_xattr_inode_lookup_create origin:upstream C 15 16d 16d 0/3 upstream: reported C repro on 2024/11/04 12:41
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/10/24 19:29 20m retest repro linux-next report log

Sample crash report:
EXT4-fs: Ignoring removed nomblk_io_submit option
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0 Not tainted
------------------------------------------------------
syz-executor171/5342 is trying to acquire lock:
ffff8880475bab98 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
ffff8880475bab98 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: ext4_xattr_inode_create fs/ext4/xattr.c:1514 [inline]
ffff8880475bab98 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: ext4_xattr_inode_lookup_create+0x1a86/0x1f90 fs/ext4/xattr.c:1596

but task is already holding lock:
ffff8880475ab410 (&ei->i_data_sem/3){++++}-{3:3}, at: ext4_truncate+0x994/0x11c0 fs/ext4/inode.c:4180

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+0x1ed/0x550 kernel/locking/lockdep.c:5825
       down_write+0x99/0x220 kernel/locking/rwsem.c:1577
       ext4_update_i_disksize fs/ext4/ext4.h:3398 [inline]
       ext4_xattr_inode_write fs/ext4/xattr.c:1452 [inline]
       ext4_xattr_inode_lookup_create+0x1707/0x1f90 fs/ext4/xattr.c:1602
       ext4_xattr_ibody_set+0x214/0x730 fs/ext4/xattr.c:2269
       ext4_xattr_set_handle+0xba6/0x1580 fs/ext4/xattr.c:2446
       ext4_xattr_set+0x280/0x3e0 fs/ext4/xattr.c:2560
       __vfs_setxattr+0x468/0x4a0 fs/xattr.c:200
       __vfs_setxattr_noperm+0x12e/0x660 fs/xattr.c:234
       vfs_setxattr+0x221/0x430 fs/xattr.c:321
       do_setxattr fs/xattr.c:629 [inline]
       path_setxattr+0x37e/0x4d0 fs/xattr.c:658
       __do_sys_setxattr fs/xattr.c:676 [inline]
       __se_sys_setxattr fs/xattr.c:672 [inline]
       __x64_sys_setxattr+0xbb/0xd0 fs/xattr.c:672
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       down_write+0x99/0x220 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:815 [inline]
       ext4_xattr_inode_create fs/ext4/xattr.c:1514 [inline]
       ext4_xattr_inode_lookup_create+0x1a86/0x1f90 fs/ext4/xattr.c:1596
       ext4_xattr_block_set+0x274/0x3980 fs/ext4/xattr.c:1916
       ext4_xattr_move_to_block fs/ext4/xattr.c:2670 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2745 [inline]
       ext4_expand_extra_isize_ea+0x12d7/0x1cf0 fs/ext4/xattr.c:2837
       __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5831
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5874 [inline]
       __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5952
       ext4_ext_truncate+0x9f/0x2b0 fs/ext4/extents.c:4457
       ext4_truncate+0xa1b/0x11c0 fs/ext4/inode.c:4185
       ext4_evict_inode+0x90f/0xf50 fs/ext4/inode.c:263
       evict+0x4e8/0x9b0 fs/inode.c:725
       __dentry_kill+0x20d/0x630 fs/dcache.c:615
       dput+0x19f/0x2b0 fs/dcache.c:857
       do_renameat2+0xda1/0x13f0 fs/namei.c:5172
       __do_sys_renameat2 fs/namei.c:5204 [inline]
       __se_sys_renameat2 fs/namei.c:5201 [inline]
       __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5201
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

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 ***

7 locks held by syz-executor171/5342:
 #0: ffff888048cac420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:515
 #1: ffff888048cac730 (&type->s_vfs_rename_key){+.+.}-{3:3}, at: lock_rename fs/namei.c:3165 [inline]
 #1: ffff888048cac730 (&type->s_vfs_rename_key){+.+.}-{3:3}, at: do_renameat2+0x5cf/0x13f0 fs/namei.c:5105
 #2: ffff8880475af0f0 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:850 [inline]
 #2: ffff8880475af0f0 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: lock_two_directories+0x145/0x220 fs/namei.c:3131
 #3: ffff8880475abf68 (&type->i_mutex_dir_key#3/5){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:850 [inline]
 #3: ffff8880475abf68 (&type->i_mutex_dir_key#3/5){+.+.}-{3:3}, at: lock_two_directories+0x16f/0x220 fs/namei.c:3132
 #4: ffff888048cac610 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1716 [inline]
 #4: ffff888048cac610 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1899 [inline]
 #4: ffff888048cac610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x2f4/0xf50 fs/ext4/inode.c:217
 #5: ffff8880475ab410 (&ei->i_data_sem/3){++++}-{3:3}, at: ext4_truncate+0x994/0x11c0 fs/ext4/inode.c:4180
 #6: ffff8880475ab250 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_trylock_xattr fs/ext4/xattr.h:161 [inline]
 #6: ffff8880475ab250 (&ei->xattr_sem){++++}-{3:3}, at: ext4_try_to_expand_extra_isize fs/ext4/inode.c:5871 [inline]
 #6: ffff8880475ab250 (&ei->xattr_sem){++++}-{3:3}, at: __ext4_mark_inode_dirty+0x491/0x880 fs/ext4/inode.c:5952

stack backtrace:
CPU: 0 UID: 0 PID: 5342 Comm: syz-executor171 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 down_write+0x99/0x220 kernel/locking/rwsem.c:1577
 inode_lock include/linux/fs.h:815 [inline]
 ext4_xattr_inode_create fs/ext4/xattr.c:1514 [inline]
 ext4_xattr_inode_lookup_create+0x1a86/0x1f90 fs/ext4/xattr.c:1596
 ext4_xattr_block_set+0x274/0x3980 fs/ext4/xattr.c:1916
 ext4_xattr_move_to_block fs/ext4/xattr.c:2670 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2745 [inline]
 ext4_expand_extra_isize_ea+0x12d7/0x1cf0 fs/ext4/xattr.c:2837
 __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5831
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5874 [inline]
 __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5952
 ext4_ext_truncate+0x9f/0x2b0 fs/ext4/extents.c:4457
 ext4_truncate+0xa1b/0x11c0 fs/ext4/inode.c:4185
 ext4_evict_inode+0x90f/0xf50 fs/ext4/inode.c:263
 evict+0x4e8/0x9b0 fs/inode.c:725
 __dentry_kill+0x20d/0x630 fs/dcache.c:615
 dput+0x19f/0x2b0 fs/dcache.c:857
 do_renameat2+0xda1/0x13f0 fs/namei.c:5172
 __do_sys_renameat2 fs/namei.c:5204 [inline]
 __se_sys_renameat2 fs/namei.c:5201 [inline]
 __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5201
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4f45132469
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:00007ffc48c22918 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 00007f4f4517b0a0 RCX: 00007f4f45132469
RDX: 0000000000000005 RSI: 0000000020000080 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffc48c22950
R10: 00000000200000c0 R11: 0000000000000246 R12: 00007ffc48c2293c
R13: 000000000000000a R14: 431bde82d7b634db R15: 00007ffc48c22970
 </TASK>

Crashes (26):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/30 14:12 upstream c1e939a21eb1 f3a00767 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root possible deadlock in ext4_xattr_inode_lookup_create
2024/09/25 19:15 linux-next 2b7275670032 349a68c4 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/18 12:41 upstream adc218676eef 571351cb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/18 12:41 upstream adc218676eef 571351cb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/15 02:28 upstream cfaaa7d010d1 77f3eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/13 15:34 upstream f1b785f4c787 62026c85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/13 00:20 upstream 3022e9d00ebe 62026c85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 20:22 upstream a9cda7c0ffed 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 13:19 upstream de2f378f2b77 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 09:47 upstream de2f378f2b77 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 09:46 upstream de2f378f2b77 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 09:44 upstream de2f378f2b77 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/10 06:23 upstream de2f378f2b77 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/08 01:05 upstream ff7afaeca1a1 c069283c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/07 10:03 upstream 7758b206117d df3dc63b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/07 04:17 upstream 7758b206117d df3dc63b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/07 04:17 upstream 7758b206117d df3dc63b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/20 04:01 linux-next 414c97c966b6 7d02db5a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/12 05:04 linux-next 929beafbe7ac 75bb1b32 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/09 15:19 linux-next 929beafbe7ac 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/09 14:24 linux-next 929beafbe7ac 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/09 06:51 linux-next 929beafbe7ac 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/11/09 06:49 linux-next 929beafbe7ac 6b856513 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/10/10 15:57 linux-next 0cca97bf2364 8fbfc0c8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/09/27 03:22 linux-next 92fc9636d147 9314348a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
2024/09/24 07:42 linux-next 4d0326b60bb7 89298aad .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in ext4_xattr_inode_lookup_create
* Struck through repros no longer work on HEAD.