[syzbot ci] Re: arch, mm: create a generic set_memory/change_page_attr core

[syzbot ci <syzbot+ciff95a07853f6d218@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v1] arch, mm: create a generic set_memory/change_page_attr core
https://lore.kernel.org/all/20260721-generic-set-memory-v0-1-v1-0-2c1fc62306b3@kernel.org
* [PATCH RFC 01/18] x86/mm/pat: Don't gate cpa_lock on debug_pagealloc_enabled()
* [PATCH RFC 02/18] x86/mm/pat: fix effective RW computation in lookup_address_in_pgd_attr()
* [PATCH RFC 03/18] x86/mm/pat: replace x86-speficic pg_level with generic pgtable_level
* [PATCH RFC 04/18] x86/mm/pat: use page table accessors for effective RW/NX bits
* [PATCH RFC 05/18] x86/mm/pat: use a generic helper for the large page size
* [PATCH RFC 06/18] x86/mm/pat: introduce an inline helper to check if alias needs update
* [PATCH RFC 07/18] x86/mm/pat: introduce cpa_handle_large_page()
* [PATCH RFC 08/18] x86/mm/pat: use cpa_split_data structure to pass split parameters
* [PATCH RFC 09/18] x86/mm/pat: use a single locked lookup for PTE verification
* [PATCH RFC 10/18] x86/mm/pat: move the large page size calculation to should_split_large_page
* [PATCH RFC 11/18] x86/mm/pat, mm: set_memory: pull change_page_attr() core to mm/
* [PATCH RFC 12/18] x86/pat/mm, mm/set_memory: abstract the CPA page table lock
* [PATCH RFC 13/18] mm/set_memory: read page table entries with pXdp_get()
* [PATCH RFC 14/18] x86/mm/pat, mm: move cpa-test to mm
* [PATCH RFC 15/18] riscv: convert set_memory to the generic CPA implementation
* [PATCH RFC 16/18] riscv: make set_direct_map_*_noflush actually noflush
* [PATCH RFC 17/18] loongarch: convert set_memory to the generic CPA implementation
* [PATCH RFC 18/18] loongarch: make set_direct_map_*_noflush actually noflush

and found the following issue:
WARNING in arch_should_split_large_page

Full report is available here:
https://ci.syzbot.org/series/08799ddb-4fca-4e5c-a2a7-a16eb2845851

***

WARNING in arch_should_split_large_page

tree:      bpf-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
base:      dc59e4fea9d83f03bad6bddf3fa2e52491777482
arch:      amd64
compiler:  Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config:    https://ci.syzbot.org/builds/9a435490-f68f-4ca0-96ae-457a5caa17e6/config

Demotion targets for Node 1: null
debug_vm_pgtable: [debug_vm_pgtable         ]: Validating architecture page table helpers
Key type .fscrypt registered
Key type fscrypt-provisioning registered
kAFS: Red Hat AFS client v0.1 registering.
Btrfs loaded, assert=on, zoned=yes, fsverity=yes
Key type big_key registered
Key type encrypted registered
AppArmor: AppArmor sha256 policy hashing enabled
ima: No TPM chip found, activating TPM-bypass!
Loading compiled-in module X.509 certificates
Loaded X.509 cert 'Build time autogenerated kernel key: dc5bfa299b381f3c121e230b24acaec0874c302b'
ima: Allocated hash algorithm: sha256
ima: No architecture policies found
evm: Initialising EVM extended attributes:
evm: security.selinux (disabled)
evm: security.SMACK64 (disabled)
evm: security.SMACK64EXEC (disabled)
evm: security.SMACK64TRANSMUTE (disabled)
evm: security.SMACK64MMAP (disabled)
evm: security.apparmor
evm: security.ima
evm: security.capability
evm: HMAC attrs: 0x1
PM:   Magic number: 2:551:79
netconsole: network logging started
gtp: GTP module loaded (pdp ctx size 128 bytes)
rdma_rxe: loaded
cfg80211: Loading compiled-in X.509 certificates for regulatory database
Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
Loaded X.509 cert 'wens: 61c038651aabdcf94bd0ac7ff06c7248db18c600'
clk: Disabling unused clocks
ALSA device list:
  #0: Dummy 1
  #1: Loopback 1
  #2: Virtual MIDI Card 1
md: Waiting for all devices to be available before autodetect
md: If you don't use raid, use raid=noautodetect
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
EXT4-fs (sda1): mounted filesystem b4773fba-1738-4da0-8a90-0fe043d0a496 ro with ordered data mode. Quota mode: none.
VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
devtmpfs: mounted
VFS: Pivoted into new rootfs
Freeing unused kernel image (initmem) memory: 26964K
Write protecting the kernel read-only data: 221184k
Testing CPA: undo ffffffff81000000-ffffffff8e800000
------------[ cut here ]------------
CPA detected W^X violation: 00000000000001a1 -> 00000000000001a3 range: 0xffffffff81000000 - 0xffffffff811fffff PFN 1000
WARNING: arch/x86/mm/pat/set_memory.c:601 at arch_should_split_large_page+0x493/0x710, CPU#0: swapper/0/1
Modules linked in:
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:arch_should_split_large_page+0x49e/0x710
Code: 00 48 8b 44 24 20 48 25 00 f0 ff ff 48 8b 4c 24 08 4c 8d 04 08 49 ff c8 48 8d 3d 4d 66 e1 0e 4c 89 ee 48 89 ea 4c 8b 4c 24 18 <67> 48 0f b9 3a eb 05 e8 46 37 4d 00 4c 89 f7 48 89 ee e8 9b 39 4d
RSP: 0000:ffffc900000679f0 EFLAGS: 00010296
RAX: 0000000000200000 RBX: 0000000000000123 RCX: ffffffff81000000
RDX: 00000000000001a3 RSI: 00000000000001a1 RDI: ffffffff905a8280
RBP: 00000000000001a3 R08: ffffffff811fffff R09: 0000000000001000
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000002
R13: 00000000000001a1 R14: 00000000000001a3 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff88818d95a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88823ffff000 CR3: 000000000e946000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __change_page_attr_set_clr+0x936/0x12d0
 change_page_attr_set_clr+0x3ac/0x450
 set_memory_rw+0x8c/0xd0
 mark_rodata_ro+0xf0/0x140
 kernel_init+0x4e/0x1d0
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

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