[v6.1] possible deadlock in f2fs_getxattr

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 75389113731b Linux 6.1.40
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16dfdfaea80000
kernel config: https://syzkaller.appspot.com/x/.config?x=19e4c20feaf8572
dashboard link: https://syzkaller.appspot.com/bug?extid=2f4b985b687de640df5b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ab09bd46ff23/disk-75389113.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/93c5d059d61a/vmlinux-75389113.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bee6a3f24d7b/Image-75389113.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2f4b98...@syzkaller.appspotmail.com

F2FS-fs (loop4): Try to recover 1th superblock, ret: 0
F2FS-fs (loop4): Mounted with checkpoint version = 753bd00b
======================================================
WARNING: possible circular locking dependency detected
6.1.40-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/6067 is trying to acquire lock:
ffff00010786c618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
ffff00010786c618 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_getxattr+0xa4/0x1198 fs/f2fs/xattr.c:531

but task is already holding lock:
ffff00010693c380 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
ffff00010693c380 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_add_regular_entry+0x6fc/0xe8c fs/f2fs/dir.c:770

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&fi->i_sem){+.+.}-{3:3}:
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x350/0x650 fs/f2fs/inline.c:645
f2fs_add_dentry fs/f2fs/dir.c:815 [inline]
f2fs_do_add_link+0x2c4/0x5a4 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_mkdir+0x2a4/0x4ec fs/f2fs/namei.c:771
vfs_mkdir+0x334/0x4e4 fs/namei.c:4036
do_mkdirat+0x20c/0x610 fs/namei.c:4061
__do_sys_mkdirat fs/namei.c:4076 [inline]
__se_sys_mkdirat fs/namei.c:4074 [inline]
__arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4074
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #0 (&fi->i_xattr_sem){.+.+}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
down_read+0x64/0x308 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xa4/0x1198 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x6c/0x5e4 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xe8/0x8e8 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0x8a8/0x11e8 fs/f2fs/dir.c:587
f2fs_add_regular_entry+0x710/0xe8c fs/f2fs/dir.c:771
f2fs_add_dentry fs/f2fs/dir.c:819 [inline]
f2fs_do_add_link+0x300/0x5a4 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x634/0x8b4 fs/f2fs/namei.c:367
lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0xeac/0x2548 fs/namei.c:3711
do_filp_open+0x1bc/0x3cc fs/namei.c:3741
do_sys_openat2+0x128/0x3d8 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1345
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);

*** DEADLOCK ***

4 locks held by syz-executor.4/6067:
#0: ffff0000d9388460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
#1: ffff00010786bfa8 (&type->i_mutex_dir_key#9){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff00010786bfa8 (&type->i_mutex_dir_key#9){+.+.}-{3:3}, at: open_last_lookups fs/namei.c:3478 [inline]
#1: ffff00010786bfa8 (&type->i_mutex_dir_key#9){+.+.}-{3:3}, at: path_openat+0x5ec/0x2548 fs/namei.c:3711
#2: ffff00010adc43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#2: ffff00010adc43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_lock_op fs/f2fs/f2fs.h:2197 [inline]
#2: ffff00010adc43b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_create+0x598/0x8b4 fs/f2fs/namei.c:366
#3: ffff00010693c380 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
#3: ffff00010693c380 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_add_regular_entry+0x6fc/0xe8c fs/f2fs/dir.c:770

stack backtrace:
CPU: 1 PID: 6067 Comm: syz-executor.4 Not tainted 6.1.40-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
down_read+0x64/0x308 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xa4/0x1198 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x6c/0x5e4 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xe8/0x8e8 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0x8a8/0x11e8 fs/f2fs/dir.c:587
f2fs_add_regular_entry+0x710/0xe8c fs/f2fs/dir.c:771
f2fs_add_dentry fs/f2fs/dir.c:819 [inline]
f2fs_do_add_link+0x300/0x5a4 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x634/0x8b4 fs/f2fs/namei.c:367
lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]
path_openat+0xeac/0x2548 fs/namei.c:3711
do_filp_open+0x1bc/0x3cc fs/namei.c:3741
do_sys_openat2+0x128/0x3d8 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__arm64_sys_openat+0x1f0/0x240 fs/open.c:1345
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


---
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If the bug is already fixed, let syzbot know by replying with:
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If the bug is a duplicate of another bug, reply with:
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If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d2a6dc4eaf6d Linux 6.1.42
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1230a829a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=54d239cfb343e1e3

dashboard link: https://syzkaller.appspot.com/bug?extid=2f4b985b687de640df5b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14559911a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1245995ea80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/48a245e1f181/disk-d2a6dc4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/36fe96f5b416/vmlinux-d2a6dc4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d53f0286f35a/bzImage-d2a6dc4e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/6231a2ce8221/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2f4b98...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 40427
F2FS-fs (loop0): Invalid log_blocksize (268), supports only 12
F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop0): Found nat_bits in checkpoint
F2FS-fs (loop0): Try to recover 1th superblock, ret: 0
F2FS-fs (loop0): Mounted with checkpoint version = 48b305e5

======================================================
WARNING: possible circular locking dependency detected

6.1.42-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor272/3538 is trying to acquire lock:
ffff8880744510a8 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
ffff8880744510a8 (&fi->i_xattr_sem){.+.+}-{3:3}, at: f2fs_getxattr+0xb4/0x1460 fs/f2fs/xattr.c:531

but task is already holding lock:

ffff888075fd16f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
ffff888075fd16f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_do_tmpfile+0x21/0x160 fs/f2fs/dir.c:869

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&fi->i_sem){+.+.}-{3:3}:

lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_write+0x36/0x60 kernel/locking/rwsem.c:1573
f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
f2fs_add_inline_entry+0x3a4/0x760 fs/f2fs/inline.c:645
f2fs_add_dentry+0xb6/0x1e0 fs/f2fs/dir.c:815
f2fs_do_add_link+0x21a/0x340 fs/f2fs/dir.c:858
f2fs_add_link fs/f2fs/f2fs.h:3530 [inline]
f2fs_create+0x749/0xa10 fs/f2fs/namei.c:367

lookup_open fs/namei.c:3413 [inline]
open_last_lookups fs/namei.c:3481 [inline]

path_openat+0x12f1/0x2e60 fs/namei.c:3711
do_filp_open+0x230/0x480 fs/namei.c:3741
do_sys_openat2+0x13b/0x500 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_creat fs/open.c:1410 [inline]
__se_sys_creat fs/open.c:1404 [inline]
__x64_sys_creat+0x11f/0x160 fs/open.c:1404
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&fi->i_xattr_sem){.+.+}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]

validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_read+0x43/0x2e0 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xb4/0x1460 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x52/0x8a0 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xd3/0x960 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0xaa0/0x11d0 fs/f2fs/dir.c:587
f2fs_do_tmpfile+0x30/0x160 fs/f2fs/dir.c:870
__f2fs_tmpfile+0x1f9/0x380 fs/f2fs/namei.c:874
f2fs_ioc_start_atomic_write fs/f2fs/file.c:2107 [inline]
__f2fs_ioctl+0x9a02/0xbf70 fs/f2fs/file.c:4171
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);
lock(&fi->i_sem);
lock(&fi->i_xattr_sem);

*** DEADLOCK ***

5 locks held by syz-executor272/3538:
#0: ffff888076186460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
#1: ffff888075fd0a38 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff888075fd0a38 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: f2fs_ioc_start_atomic_write fs/f2fs/file.c:2068 [inline]
#1: ffff888075fd0a38 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: __f2fs_ioctl+0x4142/0xbf70 fs/f2fs/file.c:4171
#2: ffff888075fd1010 (&fi->i_gc_rwsem[WRITE]){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
#2: ffff888075fd1010 (&fi->i_gc_rwsem[WRITE]){+.+.}-{3:3}, at: f2fs_ioc_start_atomic_write fs/f2fs/file.c:2082 [inline]
#2: ffff888075fd1010 (&fi->i_gc_rwsem[WRITE]){+.+.}-{3:3}, at: __f2fs_ioctl+0x5457/0xbf70 fs/f2fs/file.c:4171
#3: ffff88807d1803b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
#3: ffff88807d1803b0 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_lock_op fs/f2fs/f2fs.h:2197 [inline]
#3: ffff88807d1803b0 (&sbi->cp_rwsem){++++}-{3:3}, at: __f2fs_tmpfile+0x1ce/0x380 fs/f2fs/namei.c:869
#4: ffff888075fd16f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2179 [inline]
#4: ffff888075fd16f8 (&fi->i_sem){+.+.}-{3:3}, at: f2fs_do_tmpfile+0x21/0x160 fs/f2fs/dir.c:869

stack backtrace:
CPU: 1 PID: 3538 Comm: syz-executor272 Not tainted 6.1.42-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
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:2178

check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]

validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
down_read+0x43/0x2e0 kernel/locking/rwsem.c:1520
f2fs_down_read fs/f2fs/f2fs.h:2154 [inline]
f2fs_getxattr+0xb4/0x1460 fs/f2fs/xattr.c:531
__f2fs_get_acl+0x52/0x8a0 fs/f2fs/acl.c:179
f2fs_acl_create fs/f2fs/acl.c:375 [inline]
f2fs_init_acl+0xd3/0x960 fs/f2fs/acl.c:418
f2fs_init_inode_metadata+0xaa0/0x11d0 fs/f2fs/dir.c:587
f2fs_do_tmpfile+0x30/0x160 fs/f2fs/dir.c:870
__f2fs_tmpfile+0x1f9/0x380 fs/f2fs/namei.c:874
f2fs_ioc_start_atomic_write fs/f2fs/file.c:2107 [inline]
__f2fs_ioctl+0x9a02/0xbf70 fs/f2fs/file.c:4171
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fa316d78639
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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:


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 980b592c60874d9b8bca5663549edc73acd42946
Author: Jaegeuk Kim <jae...@kernel.org>
Date: Fri Aug 18 18:34:32 2023 +0000

f2fs: avoid false alarm of circular locking

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14ed67cd680000
start commit: 0a4a7855302d Linux 6.1.44
git tree: linux-6.1.y
kernel config: https://syzkaller.appspot.com/x/.config?x=84028051951135dc
dashboard link: https://syzkaller.appspot.com/bug?extid=2f4b985b687de640df5b
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c3ac27a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11523e69a80000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: f2fs: avoid false alarm of circular locking

For information about bisection process see: https://goo.gl/tpsmEJ#bisection