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* [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry
@ 2022-12-28  7:59 syzbot
  0 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2022-12-28  7:59 UTC (permalink / raw)
  To: adilger.kernel, linux-ext4, linux-kernel, syzkaller-bugs, tytso

Hello,

syzbot found the following issue on:

HEAD commit:    a5541c0811a0 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=124896ff880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=d3bb749184481f92deb5
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11711df8480000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161e81b0480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4b7702208fb9/disk-a5541c08.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9ec0153ec051/vmlinux-a5541c08.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f8725ad290a/Image-a5541c08.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/5ea71b2bd574/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3bb749184481f92deb5@syzkaller.appspotmail.com

EXT4-fs: Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0 Not tainted
------------------------------------------------------
syz-executor246/3073 is trying to acquire lock:
ffff0000cacbcd48 (&ei->xattr_sem){++++}-{3:3}, at: ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690

but task is already holding lock:
ffff0000cacbda10 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff0000cacbda10 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}:
       down_write+0x5c/0x88 kernel/locking/rwsem.c:1562
       inode_lock include/linux/fs.h:756 [inline]
       ext4_xattr_inode_create fs/ext4/xattr.c:1454 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1537 [inline]
       ext4_xattr_set_entry+0xde4/0xe28 fs/ext4/xattr.c:1665
       ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2225
       ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2382
       ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2496
       ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
       __vfs_setxattr+0x250/0x260 fs/xattr.c:182
       __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216
       __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277
       vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr fs/xattr.c:617 [inline]
       path_setxattr+0x354/0x414 fs/xattr.c:636
       __do_sys_lsetxattr fs/xattr.c:659 [inline]
       __se_sys_lsetxattr fs/xattr.c:655 [inline]
       __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
       lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
       down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
       ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
       __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
       ext4_find_entry fs/ext4/namei.c:1731 [inline]
       __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
       ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
       vfs_unlink+0x1dc/0x300 fs/namei.c:4252
       do_unlinkat+0x200/0x3dc fs/namei.c:4320
       __do_sys_unlinkat fs/namei.c:4363 [inline]
       __se_sys_unlinkat fs/namei.c:4356 [inline]
       __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz-executor246/3073:
 #0: ffff0000ca036460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x20/0x64 fs/namespace.c:393
 #1: ffff0000cacbd080 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
 #1: ffff0000cacbd080 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0xf0/0x3dc fs/namei.c:4303
 #2: ffff0000cacbda10 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #2: ffff0000cacbda10 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

stack backtrace:
CPU: 1 PID: 3073 Comm: syz-executor246 Not tainted 6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
 check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
 ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
 __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
 ext4_find_entry fs/ext4/namei.c:1731 [inline]
 __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
 ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
 vfs_unlink+0x1dc/0x300 fs/namei.c:4252
 do_unlinkat+0x200/0x3dc fs/namei.c:4320
 __do_sys_unlinkat fs/namei.c:4363 [inline]
 __se_sys_unlinkat fs/namei.c:4356 [inline]
 __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry
       [not found] <20221229093654.2868-1-hdanton@sina.com>
@ 2022-12-29  9:52 ` syzbot
  0 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2022-12-29  9:52 UTC (permalink / raw)
  To: hdanton, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in ext4_find_inline_entry

EXT4-fs: Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0 Not tainted
------------------------------------------------------
syz-executor.0/3645 is trying to acquire lock:
ffff0000caafc428 (&ei->xattr_sem){++++}-{3:3}, at: ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690

but task is already holding lock:
ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:757 [inline]
ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ea_inode->i_lockkey){+.+.}-{3:3}:
       down_write+0x5c/0x88 kernel/locking/rwsem.c:1562
       inode_lock include/linux/fs.h:757 [inline]
       ext4_xattr_inode_create fs/ext4/xattr.c:1455 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1538 [inline]
       ext4_xattr_set_entry+0xdf0/0xe34 fs/ext4/xattr.c:1666
       ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2226
       ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2383
       ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2497
       ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
       __vfs_setxattr+0x250/0x260 fs/xattr.c:182
       __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216
       __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277
       vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr fs/xattr.c:617 [inline]
       path_setxattr+0x354/0x414 fs/xattr.c:636
       __do_sys_lsetxattr fs/xattr.c:659 [inline]
       __se_sys_lsetxattr fs/xattr.c:655 [inline]
       __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
       lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
       down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
       ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
       __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
       ext4_find_entry fs/ext4/namei.c:1731 [inline]
       __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
       ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
       vfs_unlink+0x1dc/0x300 fs/namei.c:4252
       do_unlinkat+0x200/0x3dc fs/namei.c:4320
       __do_sys_unlinkat fs/namei.c:4363 [inline]
       __se_sys_unlinkat fs/namei.c:4356 [inline]
       __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ea_inode->i_lockkey);
                               lock(&ei->xattr_sem);
                               lock(&ea_inode->i_lockkey);
  lock(&ei->xattr_sem);

 *** DEADLOCK ***

3 locks held by syz-executor.0/3645:
 #0: ffff0000cba7a460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x20/0x64 fs/namespace.c:393
 #1: ffff0000caafc760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:792 [inline]
 #1: ffff0000caafc760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0xf0/0x3dc fs/namei.c:4303
 #2: ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:757 [inline]
 #2: ffff0000caafbdc0 (&ea_inode->i_lockkey){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

stack backtrace:
CPU: 1 PID: 3645 Comm: syz-executor.0 Not tainted 6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
 check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
 ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
 __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
 ext4_find_entry fs/ext4/namei.c:1731 [inline]
 __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
 ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
 vfs_unlink+0x1dc/0x300 fs/namei.c:4252
 do_unlinkat+0x200/0x3dc fs/namei.c:4320
 __do_sys_unlinkat fs/namei.c:4363 [inline]
 __se_sys_unlinkat fs/namei.c:4356 [inline]
 __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584


Tested on:

commit:         a5541c08 Merge branch 'for-next/core' into for-kernelci
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12e927f8480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=d3bb749184481f92deb5
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14e927f8480000


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry
       [not found] <20221229005540.2777-1-hdanton@sina.com>
@ 2022-12-29  1:23 ` syzbot
  0 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2022-12-29  1:23 UTC (permalink / raw)
  To: hdanton, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in ext4_xattr_set_entry

EXT4-fs: Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0 Not tainted
------------------------------------------------------
syz-executor.0/3668 is trying to acquire lock:
ffff0000cf16bd60 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff0000cf16bd60 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_xattr_inode_create fs/ext4/xattr.c:1453 [inline]
ffff0000cf16bd60 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1536 [inline]
ffff0000cf16bd60 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_xattr_set_entry+0xdbc/0xe00 fs/ext4/xattr.c:1664

but task is already holding lock:
ffff0000cf16b098 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff0000cf16b098 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0xd0/0x9a0 fs/ext4/xattr.c:2308

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ei->xattr_sem){++++}-{3:3}:
       down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
       ext4_xattr_get+0x90/0x418 fs/ext4/xattr.c:665
       ext4_xattr_security_get+0x40/0x54 fs/ext4/xattr_security.c:20
       __vfs_getxattr+0x1fc/0x20c fs/xattr.c:407
       cap_inode_need_killpriv+0x34/0x5c security/commoncap.c:301
       security_inode_need_killpriv+0x34/0x88 security/security.c:1422
       dentry_needs_remove_privs fs/inode.c:1995 [inline]
       __file_remove_privs+0xe0/0x308 fs/inode.c:2026
       file_modified_flags+0x60/0x330 fs/inode.c:2148
       file_modified+0x24/0x34 fs/inode.c:2177
       ext4_write_checks fs/ext4/file.c:264 [inline]
       ext4_buffered_write_iter+0x12c/0x294 fs/ext4/file.c:280
       ext4_file_write_iter+0x84/0x408 fs/ext4/file.c:700
       call_write_iter include/linux/fs.h:2199 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x2dc/0x46c fs/read_write.c:584
       ksys_write+0xb4/0x160 fs/read_write.c:637
       __do_sys_write fs/read_write.c:649 [inline]
       __se_sys_write fs/read_write.c:646 [inline]
       __arm64_sys_write+0x24/0x34 fs/read_write.c:646
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
       lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
       down_write+0x5c/0x88 kernel/locking/rwsem.c:1562
       inode_lock include/linux/fs.h:756 [inline]
       ext4_xattr_inode_create fs/ext4/xattr.c:1453 [inline]
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1536 [inline]
       ext4_xattr_set_entry+0xdbc/0xe00 fs/ext4/xattr.c:1664
       ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2224
       ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2381
       ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2495
       ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
       __vfs_setxattr+0x250/0x260 fs/xattr.c:182
       __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216
       __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277
       vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr fs/xattr.c:617 [inline]
       path_setxattr+0x354/0x414 fs/xattr.c:636
       __do_sys_lsetxattr fs/xattr.c:659 [inline]
       __se_sys_lsetxattr fs/xattr.c:655 [inline]
       __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->xattr_sem);
                               lock(&sb->s_type->i_mutex_key#8);
                               lock(&ei->xattr_sem);
  lock(&sb->s_type->i_mutex_key#8);

 *** DEADLOCK ***

3 locks held by syz-executor.0/3668:
 #0: ffff0000c9dee460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x20/0x64 fs/namespace.c:393
 #1: ffff0000cf16b3d0 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff0000cf16b3d0 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: vfs_setxattr+0xd4/0x1f4 fs/xattr.c:308
 #2: ffff0000cf16b098 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff0000cf16b098 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0xd0/0x9a0 fs/ext4/xattr.c:2308

stack backtrace:
CPU: 1 PID: 3668 Comm: syz-executor.0 Not tainted 6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
 check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
 down_write+0x5c/0x88 kernel/locking/rwsem.c:1562
 inode_lock include/linux/fs.h:756 [inline]
 ext4_xattr_inode_create fs/ext4/xattr.c:1453 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1536 [inline]
 ext4_xattr_set_entry+0xdbc/0xe00 fs/ext4/xattr.c:1664
 ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2224
 ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2381
 ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2495
 ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
 __vfs_setxattr+0x250/0x260 fs/xattr.c:182
 __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216
 __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277
 vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr fs/xattr.c:617 [inline]
 path_setxattr+0x354/0x414 fs/xattr.c:636
 __do_sys_lsetxattr fs/xattr.c:659 [inline]
 __se_sys_lsetxattr fs/xattr.c:655 [inline]
 __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584


Tested on:

commit:         a5541c08 Merge branch 'for-next/core' into for-kernelci
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16f5d4bc480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=d3bb749184481f92deb5
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15be6de4480000


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry
       [not found] <20221228093841.2684-1-hdanton@sina.com>
@ 2022-12-28  9:50 ` syzbot
  0 siblings, 0 replies; 4+ messages in thread
From: syzbot @ 2022-12-28  9:50 UTC (permalink / raw)
  To: hdanton, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in ext4_find_inline_entry

EXT4-fs: Warning: mounting with an experimental mount option 'dioread_nolock' for blocksize < PAGE_SIZE
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0 Not tainted
------------------------------------------------------
syz-executor.0/3637 is trying to acquire lock:
ffff0000d11c93e8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690

but task is already holding lock:
ffff0000d11ca0b0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff0000d11ca0b0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}:
       down_write+0x5c/0x88 kernel/locking/rwsem.c:1562
       inode_lock include/linux/fs.h:756 [inline]
       ext4_xattr_inode_write+0x2f0/0x460 fs/ext4/xattr.c:1400
       ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1538 [inline]
       ext4_xattr_set_entry+0xd38/0xe08 fs/ext4/xattr.c:1662
       ext4_xattr_ibody_set+0x94/0x184 fs/ext4/xattr.c:2222
       ext4_xattr_set_handle+0x648/0x9a0 fs/ext4/xattr.c:2379
       ext4_xattr_set+0x100/0x1d0 fs/ext4/xattr.c:2493
       ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
       __vfs_setxattr+0x250/0x260 fs/xattr.c:182
       __vfs_setxattr_noperm+0xcc/0x320 fs/xattr.c:216
       __vfs_setxattr_locked+0x16c/0x194 fs/xattr.c:277
       vfs_setxattr+0xf4/0x1f4 fs/xattr.c:309
       do_setxattr fs/xattr.c:594 [inline]
       setxattr fs/xattr.c:617 [inline]
       path_setxattr+0x354/0x414 fs/xattr.c:636
       __do_sys_lsetxattr fs/xattr.c:659 [inline]
       __se_sys_lsetxattr fs/xattr.c:655 [inline]
       __arm64_sys_lsetxattr+0x2c/0x40 fs/xattr.c:655
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

-> #0 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
       lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
       down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
       ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
       __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
       ext4_find_entry fs/ext4/namei.c:1731 [inline]
       __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
       ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
       vfs_unlink+0x1dc/0x300 fs/namei.c:4252
       do_unlinkat+0x200/0x3dc fs/namei.c:4320
       __do_sys_unlinkat fs/namei.c:4363 [inline]
       __se_sys_unlinkat fs/namei.c:4356 [inline]
       __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
       el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
       el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz-executor.0/3637:
 #0: ffff0000cabc0460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x20/0x64 fs/namespace.c:393
 #1: ffff0000d11c9720 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
 #1: ffff0000d11c9720 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0xf0/0x3dc fs/namei.c:4303
 #2: ffff0000d11ca0b0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #2: ffff0000d11ca0b0 (&ea_inode->i_rwsem#8/1){+.+.}-{3:3}, at: vfs_unlink+0x78/0x300 fs/namei.c:4241

stack backtrace:
CPU: 0 PID: 3637 Comm: syz-executor.0 Not tainted 6.1.0-rc8-syzkaller-00172-ga5541c0811a0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055
 check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1509
 ext4_find_inline_entry+0x80/0x224 fs/ext4/inline.c:1690
 __ext4_find_entry+0xe8/0xb4c fs/ext4/namei.c:1596
 ext4_find_entry fs/ext4/namei.c:1731 [inline]
 __ext4_unlink+0xa8/0x3e4 fs/ext4/namei.c:3215
 ext4_unlink+0x150/0x200 fs/ext4/namei.c:3291
 vfs_unlink+0x1dc/0x300 fs/namei.c:4252
 do_unlinkat+0x200/0x3dc fs/namei.c:4320
 __do_sys_unlinkat fs/namei.c:4363 [inline]
 __se_sys_unlinkat fs/namei.c:4356 [inline]
 __arm64_sys_unlinkat+0x7c/0xa8 fs/namei.c:4356
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584


Tested on:

commit:         a5541c08 Merge branch 'for-next/core' into for-kernelci
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10d9aec4480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=d3bb749184481f92deb5
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15213e32480000


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2022-12-29  9:57 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-12-28  7:59 [syzbot] [ext4?] possible deadlock in ext4_find_inline_entry syzbot
     [not found] <20221228093841.2684-1-hdanton@sina.com>
2022-12-28  9:50 ` syzbot
     [not found] <20221229005540.2777-1-hdanton@sina.com>
2022-12-29  1:23 ` syzbot
     [not found] <20221229093654.2868-1-hdanton@sina.com>
2022-12-29  9:52 ` syzbot

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