[syzbot ci] Re: mm/page_alloc: use batch page clearing in kernel_init_pages()

syzbot ci
2026-04-08T11:32:58Z

syzbot ci has tested the following series

[v1] mm/page_alloc: use batch page clearing in kernel_init_pages()
https://lore.kernel.org/all/20260408092441.435133-1-hsalunke@amd.com
* [PATCH] mm/page_alloc: use batch page clearing in kernel_init_pages()

and found the following issue:
WARNING in preempt_model_full

Full report is available here:
https://ci.syzbot.org/series/be6c0534-641b-42aa-8b73-ab8f592ec267

***

WARNING in preempt_model_full

tree: mm-new
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm.git
base: 0d90551ea699ef3d1a85cd7a1a7e21e8d4f04db2
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/22cbd293-31c6-46b9-b8d4-2ff590ce406b/config

CPU topo: Max. logical packages: 2
CPU topo: Max. logical nodes: 1
CPU topo: Num. nodes per package: 1
CPU topo: Max. logical dies: 2
CPU topo: Max. dies per package: 1
CPU topo: Max. threads per core: 1
CPU topo: Num. cores per package: 1
CPU topo: Num. threads per package: 1
CPU topo: Allowing 2 present CPUs plus 0 hotplug CPUs
kvm-guest: APIC: eoi() replaced with kvm_guest_apic_eoi_write()
PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
PM: hibernation: Registered nosave memory: [mem 0x0009f000-0x000fffff]
PM: hibernation: Registered nosave memory: [mem 0x7ffdf000-0xffffffff]
[gap 0xc0000000-0xfed1bfff] available for PCI devices
Booting paravirtualized kernel on KVM
clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
Zone ranges:
DMA [mem 0x0000000000001000-0x0000000000ffffff]
DMA32 [mem 0x0000000001000000-0x00000000ffffffff]
Normal [mem 0x0000000100000000-0x000000023fffffff]
Device empty
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x0000000000001000-0x000000000009efff]
node 0: [mem 0x0000000000100000-0x000000007ffdefff]
node 0: [mem 0x0000000100000000-0x0000000160000fff]
node 1: [mem 0x0000000160001000-0x000000023fffffff]
Initmem setup node 0 [mem 0x0000000000001000-0x0000000160000fff]
Initmem setup node 1 [mem 0x0000000160001000-0x000000023fffffff]
On node 0, zone DMA: 1 pages in unavailable ranges
On node 0, zone DMA: 97 pages in unavailable ranges
On node 0, zone Normal: 33 pages in unavailable ranges
setup_percpu: NR_CPUS:8 nr_cpumask_bits:2 nr_cpu_ids:2 nr_node_ids:2
percpu: Embedded 71 pages/cpu s250120 r8192 d32504 u2097152
kvm-guest: PV spinlocks disabled, no host support
Kernel command line: earlyprintk=serial net.ifnames=0 sysctl.kernel.hung_task_all_cpu_backtrace=1 ima_policy=tcb nf-conntrack-ftp.ports=20000 nf-conntrack-tftp.ports=20000 nf-conntrack-sip.ports=20000 nf-conntrack-irc.ports=20000 nf-conntrack-sane.ports=20000 binder.debug_mask=0 rcupdate.rcu_expedited=1 rcupdate.rcu_cpu_stall_cputime=1 no_hash_pointers page_owner=on sysctl.vm.nr_hugepages=4 sysctl.vm.nr_overcommit_hugepages=4 secretmem.enable=1 sysctl.max_rcu_stall_to_panic=1 msr.allow_writes=off coredump_filter=0xffff root=/dev/sda console=ttyS0 vsyscall=native numa=fake=2 kvm-intel.nested=1 spec_store_bypass_disable=prctl nopcid vivid.n_devs=64 vivid.multiplanar=1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2 netrom.nr_ndevs=32 rose.rose_ndevs=32 smp.csd_lock_timeout=100000 watchdog_thresh=55 workqueue.watchdog_thresh=140 sysctl.net.core.netdev_unregister_timeout_secs=140 dummy_hcd.num=32 max_loop=32 nbds_max=32 \
Kernel command line: comedi.comedi_num_legacy_minors=4 panic_on_warn=1 root=/dev/sda console=ttyS0 root=/dev/sda1
Unknown kernel command line parameters "nbds_max=32", will be passed to user space.
printk: log buffer data + meta data: 262144 + 917504 = 1179648 bytes
software IO TLB: area num 2.
Fallback order for Node 0: 0 1
Fallback order for Node 1: 1 0
Built 2 zonelists, mobility grouping on. Total pages: 1834877
Policy zone: Normal
mem auto-init: stack:all(zero), heap alloc:on, heap free:off
stackdepot: allocating hash table via alloc_large_system_hash
stackdepot hash table entries: 1048576 (order: 12, 16777216 bytes, linear)
stackdepot: allocating space for 8192 stack pools via memblock
------------[ cut here ]------------
preempt_dynamic_mode == preempt_dynamic_undefined
WARNING: kernel/sched/core.c:7743 at preempt_model_full+0x1e/0x30, CPU#0: swapper/0
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted syzkaller #0 PREEMPT(undef)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:preempt_model_full+0x1e/0x30
Code: 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 83 3d 35 d9 cb 0c ff 74 10 83 3d 2c d9 cb 0c 02 0f 94 c0 2e e9 93 fa 19 0a 90 <0f> 0b 90 eb ea 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90
RSP: 0000:ffffffff8e407a78 EFLAGS: 00010046
RAX: 1ffffffff1c359d9 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffea0004000000
RBP: 0000000000040100 R08: ffffffff8221aafb R09: 0000000000000000
R10: ffffed1020000000 R11: ffffed1024206961 R12: 0000000000000001
R13: 0000000000000001 R14: ffff888100000000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88818de62000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88823ffff000 CR3: 000000000e54c000 CR4: 00000000000000b0
Call Trace:
<TASK>
kernel_init_pages+0x6d/0xe0
post_alloc_hook+0xae/0x1e0
get_page_from_freelist+0x24ba/0x2540
__alloc_frozen_pages_noprof+0x18d/0x380
alloc_pages_mpol+0x235/0x490
alloc_pages_noprof+0xac/0x2a0
__pud_alloc+0x3a/0x460
preallocate_vmalloc_pages+0x386/0x3d0
mm_core_init+0x79/0xb0
start_kernel+0x15a/0x3d0
x86_64_start_reservations+0x24/0x30
x86_64_start_kernel+0x143/0x1c0
common_startup_64+0x13e/0x147
</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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