Re: [syzbot] [bcachefs?] BUG: unable to handle kernel paging request in bch2_fs_btree_key_cache_exit

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    6a71d2909427 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=157bb450980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fca646cf17cc616b
dashboard link: https://syzkaller.appspot.com/bug?extid=a35cdb62ec34d44fb062
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=124d68a7180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c77d21fa1405/disk-6a71d290.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/429fcd369816/vmlinux-6a71d290.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d3d8a4b85112/Image-6a71d290.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/5eb4d59a9b9e/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a35cdb62ec34d44fb062@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 32768
workqueue: Failed to create a rescuer kthread for wq "bcachefs": -EINTR
bcachefs (1e246536-b1b3-4f86-83c2-3dfcc2979a4c): shutdown complete
Unable to handle kernel paging request at virtual address ffff7000249ff210
KASAN: probably wild-memory-access in range [0xffff800124ff9080-0xffff800124ff9087]
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, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000001ad5bd000
[ffff7000249ff210] pgd=0000000000000000, p4d=000000023e882003, pud=000000023e880003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 6351 Comm: syz-executor.0 Not tainted 6.9.0-rc4-syzkaller-g6a71d2909427 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
pstate: 80401005 (Nzcv daif +PAN -UAO -TCO -DIT +SSBS BTYPE=--)
pc : bch2_fs_btree_key_cache_exit+0x7ec/0xfcc fs/bcachefs/btree_key_cache.c:974
lr : bch2_fs_btree_key_cache_exit+0x78c/0xfcc fs/bcachefs/btree_key_cache.c:970
sp : ffff8000a19f6e80
x29: ffff8000a19f6f50 x28: 1fffe0001df60010
 x27: ffff0000efb044b0
x26: 1ffff0001433ede0 x25: dfff800000000000 x24: 1ffff0001168e5d4
x23: 0000000000000000 x22: ffff800124ff9080 x21: ffff8000a19f6f00
x20: ffff80008ee81218
 x19: dfff800000000000 x18: ffff8000a19f6960
x17: 0000000000017999 x16: ffff8000802896e4 x15: 0000000000000001
x14: 1fffe0001df60898 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001df60899 x10: 0000000000ff0100 x9 : 0000000000000003
x8 : 1ffff000249ff210 x7 : ffff80008275d4e8 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff80008275d4f8
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000008
Call trace:
 bch2_fs_btree_key_cache_exit+0x7ec/0xfcc fs/bcachefs/btree_key_cache.c:974
 __bch2_fs_free fs/bcachefs/super.c:562 [inline]
 bch2_fs_release+0x1e0/0x564 fs/bcachefs/super.c:609
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x2a8/0x41c lib/kobject.c:737
 bch2_fs_free+0x288/0x2f0 fs/bcachefs/super.c:674
 bch2_fs_alloc+0xe4c/0x1c60 fs/bcachefs/super.c:965
 bch2_fs_open+0x740/0xb64 fs/bcachefs/super.c:2080
 bch2_mount+0x558/0xe10 fs/bcachefs/fs.c:1900
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:662
 vfs_get_tree+0x90/0x288 fs/super.c:1779
 do_new_mount+0x278/0x900 fs/namespace.c:3352
 path_mount+0x590/0xe04 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount fs/namespace.c:3875 [inline]
 __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3875
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Code: f90027e8 d343fec8 11000d29 f9002be8 (38f36908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	f90027e8 	str	x8, [sp, #72]
   4:	d343fec8 	lsr	x8, x22, #3
   8:	11000d29 	add	w9, w9, #0x3
   c:	f9002be8 	str	x8, [sp, #80]
* 10:	38f36908 	ldrsb	w8, [x8, x19] <-- trapping instruction


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