[syzbot] [mm?] [bcachefs?] general protection fault in xas_create

[syzbot <syzbot+85a56f124ac1ea0ac0cb@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0fed89a961ea Merge tag 'hyperv-fixes-signed-20250311' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ea1874580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=31c94a07ddad0b00
dashboard link: https://syzkaller.appspot.com/bug?extid=85a56f124ac1ea0ac0cb
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=16124c78580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-0fed89a9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9e4d0fd4258e/vmlinux-0fed89a9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea186f3b1240/bzImage-0fed89a9.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/2c3be83f8b9f/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+85a56f124ac1ea0ac0cb@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0x7d0034f00001880: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5719 Comm: syz.4.37 Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:get_freepointer mm/slub.c:504 [inline]
RIP: 0010:get_freepointer_safe mm/slub.c:532 [inline]
RIP: 0010:__slab_alloc_node mm/slub.c:3993 [inline]
RIP: 0010:slab_alloc_node mm/slub.c:4152 [inline]
RIP: 0010:kmem_cache_alloc_lru_noprof+0xed/0x390 mm/slub.c:4183
Code: 0f 84 8e 01 00 00 41 83 f8 ff 74 1a 48 8b 03 48 83 f8 ff 0f 84 97 02 00 00 48 c1 e8 3a 41 39 c0 0f 85 6e 01 00 00 41 8b 47 28 <4a> 8b 1c 20 49 8d 4d 08 49 8b 37 4c 89 e0 4c 89 ea 65 48 0f c7 0e
RSP: 0018:ffffc9000d037478 EFLAGS: 00010046
RAX: 0000000000000240 RBX: ffffea0000ecb880 RCX: 0000000000043ba0
RDX: 0000000000000001 RSI: 0000000000000240 RDI: ffffffff8ec54460
RBP: ffffffff8c06a1c0 R08: 00000000ffffffff R09: fffff52001a06ea8
R10: dffffc0000000000 R11: fffff52001a06ea8 R12: 07d0034f00001640
R13: 0000000000016220 R14: 0000000000402800 R15: ffff88801b04fdc0
FS:  00007fd8409fe6c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa6ac013000 CR3: 0000000012b64000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 xas_alloc lib/xarray.c:377 [inline]
 xas_create+0x10d0/0x1ae0 lib/xarray.c:684
 xas_store+0x96/0x1870 lib/xarray.c:794
 shmem_add_to_page_cache+0x89d/0xcc0 mm/shmem.c:897
 shmem_alloc_and_add_folio+0x968/0x1090 mm/shmem.c:1928
 shmem_get_folio_gfp+0x621/0x1840 mm/shmem.c:2545
 shmem_get_folio mm/shmem.c:2651 [inline]
 shmem_write_begin+0x165/0x350 mm/shmem.c:3301
 generic_perform_write+0x346/0x990 mm/filemap.c:4188
 shmem_file_write_iter+0xf9/0x120 mm/shmem.c:3477
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0xacf/0xd10 fs/read_write.c:679
 ksys_write+0x18f/0x2b0 fs/read_write.c:731
 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: 0033:0x7fd84178bc1f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007fd8409fddf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007fd84178bc1f
RDX: 0000000001000000 RSI: 00007fd838400000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000590c
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003
R13: 00007fd8409fdef0 R14: 00007fd8409fdeb0 R15: 00007fd838400000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:get_freepointer mm/slub.c:504 [inline]
RIP: 0010:get_freepointer_safe mm/slub.c:532 [inline]
RIP: 0010:__slab_alloc_node mm/slub.c:3993 [inline]
RIP: 0010:slab_alloc_node mm/slub.c:4152 [inline]
RIP: 0010:kmem_cache_alloc_lru_noprof+0xed/0x390 mm/slub.c:4183
Code: 0f 84 8e 01 00 00 41 83 f8 ff 74 1a 48 8b 03 48 83 f8 ff 0f 84 97 02 00 00 48 c1 e8 3a 41 39 c0 0f 85 6e 01 00 00 41 8b 47 28 <4a> 8b 1c 20 49 8d 4d 08 49 8b 37 4c 89 e0 4c 89 ea 65 48 0f c7 0e
RSP: 0018:ffffc9000d037478 EFLAGS: 00010046
RAX: 0000000000000240 RBX: ffffea0000ecb880 RCX: 0000000000043ba0
RDX: 0000000000000001 RSI: 0000000000000240 RDI: ffffffff8ec54460
RBP: ffffffff8c06a1c0 R08: 00000000ffffffff R09: fffff52001a06ea8
R10: dffffc0000000000 R11: fffff52001a06ea8 R12: 07d0034f00001640
R13: 0000000000016220 R14: 0000000000402800 R15: ffff88801b04fdc0
FS:  00007fd8409fe6c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa6ac013000 CR3: 0000000012b64000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	0f 84 8e 01 00 00    	je     0x194
   6:	41 83 f8 ff          	cmp    $0xffffffff,%r8d
   a:	74 1a                	je     0x26
   c:	48 8b 03             	mov    (%rbx),%rax
   f:	48 83 f8 ff          	cmp    $0xffffffffffffffff,%rax
  13:	0f 84 97 02 00 00    	je     0x2b0
  19:	48 c1 e8 3a          	shr    $0x3a,%rax
  1d:	41 39 c0             	cmp    %eax,%r8d
  20:	0f 85 6e 01 00 00    	jne    0x194
  26:	41 8b 47 28          	mov    0x28(%r15),%eax
* 2a:	4a 8b 1c 20          	mov    (%rax,%r12,1),%rbx <-- trapping instruction
  2e:	49 8d 4d 08          	lea    0x8(%r13),%rcx
  32:	49 8b 37             	mov    (%r15),%rsi
  35:	4c 89 e0             	mov    %r12,%rax
  38:	4c 89 ea             	mov    %r13,%rdx
  3b:	65 48 0f c7 0e       	cmpxchg16b %gs:(%rsi)


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