[v6.1] BUG: unable to handle kernel paging request in write_all_supers

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dfc486ec9cce Linux 6.1.144
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16731d82580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f8c435072b93fddd
dashboard link: https://syzkaller.appspot.com/bug?extid=a330f26f8dd693d718f3
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/be2756a32e51/disk-dfc486ec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fb99deb14858/vmlinux-dfc486ec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c651d3cff1de/Image-dfc486ec.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a330f2...@syzkaller.appspotmail.com

BTRFS info (device loop4: state C): enabling ssd optimizations
BTRFS error (device loop4: state MC): unrecognized mount option 'L'
Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4448 Comm: syz.4.9 Not tainted 6.1.144-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : backup_super_roots fs/btrfs/disk-io.c:2007 [inline]
pc : write_all_supers+0x8d4/0x35a8 fs/btrfs/disk-io.c:4357
lr : lowmem_page_address include/linux/mm.h:1805 [inline]
lr : btrfs_header_level fs/btrfs/ctree.h:2375 [inline]
lr : backup_super_roots fs/btrfs/disk-io.c:2005 [inline]
lr : write_all_supers+0x82c/0x35a8 fs/btrfs/disk-io.c:4357
sp : ffff800020fe72c0
x29: ffff800020fe7620 x28: 1ffff00002959078 x27: 0000000000000009
x26: 0000000000000003 x25: ffff0000d294ebc5 x24: ffff0000dda646c8
x23: ffff0000d294eb2b x22: ffff800014ac8000 x21: dfff800000000000
x20: dfff800000000000 x19: 0000000000000018 x18: ffff800011aabce0
x17: ffff8000181e6000 x16: ffff8000082e8124 x15: ffff800017cc6fc0
x14: ffff0000dcfaa658 x13: 1ffff00002a160b1 x12: 0000000000ff0100
x11: ff00800009f33194 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff800009f260c4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082e8180
x2 : 0000000000000001 x1 : 0000000000000000 x0 : ffff0000da4eba50
Call trace:
backup_super_roots fs/btrfs/disk-io.c:2007 [inline]
write_all_supers+0x8d4/0x35a8 fs/btrfs/disk-io.c:4357
btrfs_commit_transaction+0x19b4/0x29f0 fs/btrfs/transaction.c:2511
btrfs_set_free_space_cache_v1_active+0x7c/0x258 fs/btrfs/free-space-cache.c:4134
btrfs_remount_cleanup fs/btrfs/super.c:1992 [inline]
btrfs_remount+0x5b8/0x1148 fs/btrfs/super.c:2182
legacy_reconfigure+0xf8/0x110 fs/fs_context.c:655
reconfigure_super+0x1d4/0x79c fs/super.c:977
do_remount fs/namespace.c:2714 [inline]
path_mount+0xbd4/0xe78 fs/namespace.c:3380
do_mount fs/namespace.c:3401 [inline]
__do_sys_mount fs/namespace.c:3609 [inline]
__se_sys_mount fs/namespace.c:3586 [inline]
__arm64_sys_mount+0x49c/0x584 fs/namespace.c:3586
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 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:585
Code: d2d00014 f2fbfff4 91006113 d343fe7a (38756b48)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: d2d00014 mov x20, #0x800000000000 // #140737488355328
4: f2fbfff4 movk x20, #0xdfff, lsl #48
8: 91006113 add x19, x8, #0x18
c: d343fe7a lsr x26, x19, #3
* 10: 38756b48 ldrb w8, [x26, x21] <-- trapping instruction


---
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 syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: dfc486ec9cce Linux 6.1.144
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=16e807d4580000

kernel config: https://syzkaller.appspot.com/x/.config?x=f8c435072b93fddd
dashboard link: https://syzkaller.appspot.com/bug?extid=a330f26f8dd693d718f3
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=178850f0580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=140c018c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/be2756a32e51/disk-dfc486ec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fb99deb14858/vmlinux-dfc486ec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c651d3cff1de/Image-dfc486ec.gz.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/70b31806afa6/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=134f1d82580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a330f2...@syzkaller.appspotmail.com

workqueue: max_active 2097158 requested for btrfs-compressed-write is out of range, clamping between 1 and 512
BTRFS info (device loop0: state C): enabling ssd optimizations
BTRFS error (device loop0: state MC): unrecognized mount option 'L'

Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:

CPU: 1 PID: 4461 Comm: syz.0.16 Not tainted 6.1.144-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : backup_super_roots fs/btrfs/disk-io.c:2007 [inline]
pc : write_all_supers+0x8d4/0x35a8 fs/btrfs/disk-io.c:4357
lr : lowmem_page_address include/linux/mm.h:1805 [inline]
lr : btrfs_header_level fs/btrfs/ctree.h:2375 [inline]
lr : backup_super_roots fs/btrfs/disk-io.c:2005 [inline]
lr : write_all_supers+0x82c/0x35a8 fs/btrfs/disk-io.c:4357

sp : ffff8000209f72c0
x29: ffff8000209f7620 x28: 1ffff00002959078 x27: 0000000000000009
x26: 0000000000000003 x25: ffff0000d2864bc5 x24: ffff0000dbdf46c8
x23: ffff0000d2864b2b x22: ffff800014ac8000 x21: dfff800000000000

x20: dfff800000000000 x19: 0000000000000018 x18: ffff800011aabce0
x17: ffff8000181e6000 x16: ffff8000082e8124 x15: ffff800017cc6fc0

x14: ffff0000cddf4218 x13: 1ffff00002a160b1 x12: 0000000000ff0100

x11: ff00800009f33194 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff800009f260c4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082e8180

x2 : 0000000000000001 x1 : 0000000000000000 x0 : ffff0000d2133a50

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.