Re: [syzbot] [kernel?] linux-next test error: WARNING: locking bug in change_page_attr_set_clr

[Borislav Petkov]

Adding all folks who touched this recently.

On Mon, Jul 20, 2026 at 09:59:25AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    1a1757b76427 Add linux-next specific files for 20260716
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=16c734b9580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8d1a274c57796a86
> dashboard link: https://syzkaller.appspot.com/bug?extid=ee7ecfcd0e3f185e835a
> compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/923ee89ba238/disk-1a1757b7.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cb34d1bf205c/vmlinux-1a1757b7.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/bf183d434c82/bzImage-1a1757b7.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+ee7ecfcd0e3f185e835a@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
> kfence: initialized - using 2097152 bytes for 255 objects at 0xffff88823be00000-0xffff88823c000000
> Console: colour VGA+ 80x25
> printk: legacy console [ttyS0] enabled
> printk: legacy console [ttyS0] enabled
> printk: legacy bootconsole [earlyser0] disabled
> printk: legacy bootconsole [earlyser0] disabled
> Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
> ... MAX_LOCKDEP_SUBCLASSES:  8
> ... MAX_LOCK_DEPTH:          48
> ... MAX_LOCKDEP_KEYS:        8192
> ... CLASSHASH_SIZE:          4096
> ... MAX_LOCKDEP_ENTRIES:     1048576
> ... MAX_LOCKDEP_CHAINS:      1048576
> ... CHAINHASH_SIZE:          524288
>  memory used by lock dependency info: 106625 kB
>  memory used for stack traces: 8320 kB
>  per task-struct memory footprint: 1920 bytes
> mempolicy: Enabling automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl
> ACPI: Core revision 20260408
> APIC: Switch to symmetric I/O mode setup
> x2apic enabled
> APIC: Switched APIC routing to: physical x2apic
> ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
> clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x1fb63109b96, max_idle_ns: 440795265316 ns
> Calibrating delay loop (skipped) preset value.. 4399.99 BogoMIPS (lpj=21999980)
> Last level iTLB entries: 4KB 64, 2MB 8, 4MB 8
> Last level dTLB entries: 4KB 64, 2MB 32, 4MB 32, 1GB 4
> mitigations: Enabled attack vectors: user_kernel, user_user, guest_host, guest_guest, SMT mitigations: auto
> Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl
> Spectre V2 : Mitigation: IBRS
> RETBleed: Mitigation: IBRS
> ITS: Mitigation: Aligned branch/return thunks
> Spectre V2 : User space: Mitigation: STIBP via prctl
> MDS: Mitigation: Clear CPU buffers
> TAA: Mitigation: Clear CPU buffers
> MMIO Stale Data: Vulnerable: Clear CPU buffers attempted, no microcode
> Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
> Spectre V2 : Spectre v2 / SpectreRSB: Filling RSB on context switch and VMEXIT
> Spectre V2 : Enabling IBPB for BPF
> Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier
> active return thunk: its_return_thunk
> Spectre V2 : Spectre BHI mitigation: SW BHB clearing on syscall and VM exit
> x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
> x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
> x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
> x86/fpu: xstate_offset[2]:  576, xstate_sizes[2]:  256
> x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format.
> 
> =============================
> [ BUG: Invalid wait context ]
> syzkaller #0 Not tainted
> -----------------------------
> swapper/0/0 is trying to lock:
> ffffffff8f088c78 ((init_mm).mmap_lock){....}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
> ffffffff8f088c78 ((init_mm).mmap_lock){....}-{4:4}, at: class_mmap_read_lock_constructor include/linux/mmap_lock.h:631 [inline]
> ffffffff8f088c78 ((init_mm).mmap_lock){....}-{4:4}, at: cpa_collapse_large_pages arch/x86/mm/pat/set_memory.c:448 [inline]
> ffffffff8f088c78 ((init_mm).mmap_lock){....}-{4:4}, at: cpa_flush arch/x86/mm/pat/set_memory.c:494 [inline]
> ffffffff8f088c78 ((init_mm).mmap_lock){....}-{4:4}, at: change_page_attr_set_clr+0xc2c/0x1010 arch/x86/mm/pat/set_memory.c:2142
> other info that might help us debug this:
> context-{5:5}
> locks held by swapper/0/0: 1, last CPU#0:
>  #0: ffffffff8edc2078 (cpa_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
>  #0: ffffffff8edc2078 (cpa_lock){+.+.}-{3:3}, at: cpa_collapse_large_pages arch/x86/mm/pat/set_memory.c:421 [inline]
>  #0: ffffffff8edc2078 (cpa_lock){+.+.}-{3:3}, at: cpa_flush arch/x86/mm/pat/set_memory.c:494 [inline]
>  #0: ffffffff8edc2078 (cpa_lock){+.+.}-{3:3}, at: change_page_attr_set_clr+0x967/0x1010 arch/x86/mm/pat/set_memory.c:2142
> stack backtrace:
> CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_lock_invalid_wait_context kernel/locking/lockdep.c:4846 [inline]
>  check_wait_context kernel/locking/lockdep.c:4918 [inline]
>  __lock_acquire+0xef0/0x2e50 kernel/locking/lockdep.c:5204
>  lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5906
>  down_read+0x4a/0x330 kernel/locking/rwsem.c:1574
>  mmap_read_lock include/linux/mmap_lock.h:600 [inline]
>  class_mmap_read_lock_constructor include/linux/mmap_lock.h:631 [inline]
>  cpa_collapse_large_pages arch/x86/mm/pat/set_memory.c:448 [inline]
>  cpa_flush arch/x86/mm/pat/set_memory.c:494 [inline]
>  change_page_attr_set_clr+0xc2c/0x1010 arch/x86/mm/pat/set_memory.c:2142
>  set_memory_rox+0xbe/0x100 arch/x86/mm/pat/set_memory.c:2341
>  its_pages_protect arch/x86/kernel/alternative.c:168 [inline]
>  its_fini_core arch/x86/kernel/alternative.c:175 [inline]
>  alternative_instructions+0x95/0x100 arch/x86/kernel/alternative.c:2264
>  arch_cpu_finalize_init+0xb2/0x1f0 arch/x86/kernel/cpu/common.c:2633
>  start_kernel+0x310/0x3e0 init/main.c:1153
>  x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
>  x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291
>  common_startup_64+0x13e/0x157
>  </TASK>
> pid_max: default: 32768 minimum: 301
> landlock: Up and running.
> Yama: becoming mindful.
> TOMOYO Linux initialized
> AppArmor: AppArmor initialized
> LSM support for eBPF active
> Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, vmalloc hugepage)
> Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes, vmalloc hugepage)
> Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, vmalloc)
> Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, vmalloc)
> VFS: Finished mounting rootfs on nullfs
> Running RCU synchronous self tests
> Running RCU synchronous self tests
> numa_add_cpu cpu 1 node 0: mask now 0-1
> numa_add_cpu cpu 1 node 1: mask now 0-1
> 
> 
> ---
> 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 syzkaller@xxxxxxxxxxxxxxxx.
> 
> 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

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette