Re: [harry:kmalloc-no-objext-rfc-v1r3] [mm/slab] d6967566f4: RIP:mark_obj_codetag_empty

Harry Yoo <[email protected]> Thu, 16 Jul 2026 11:27:11 +0900
Newsgroups dev.linux.lists.oe-lkp,org.kvack.linux-mm
Message-ID <[email protected]>
This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--------------wHkUIB4ELmmhRpV9tINOU1eM
Content-Type: multipart/mixed; boundary="------------jUyNbDSOZ26IDnD3L0wPmVkN";
 protected-headers="v1"
From: Harry Yoo <[email protected]>
To: kernel test robot <[email protected]>
Cc: [email protected], [email protected],
 Danielle Costantino <[email protected]>,
 Shakeel Butt <[email protected]>, [email protected]
Message-ID: <[email protected]>
Subject: Re: [harry:kmalloc-no-objext-rfc-v1r3] [mm/slab] d6967566f4:
 RIP:mark_obj_codetag_empty
References: <[email protected]>
In-Reply-To: <[email protected]>

--------------jUyNbDSOZ26IDnD3L0wPmVkN
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable


Thanks for reporting!

Indeed I've seen this false warning and it was fixed in v2.

On 7/14/26 10:48 PM, kernel test robot wrote:
> Hello,
>=20
> kernel test robot noticed "RIP:mark_obj_codetag_empty" on:
>=20
> commit: d6967566f41090d5e58861f3b5d3d9b1293ccb0f ("mm/slab: prevent unb=
ounded recursion in free path with new kmalloc type")
> https://git.kernel.org/cgit/linux/kernel/git/harry/linux.git kmalloc-no=
-objext-rfc-v1r3
>=20
> in testcase: locktorture
> version:=20
> with following parameters:
>=20
> 	runtime: 300s
> 	test: cpuhotplug
>=20
>=20
>=20
> config: x86_64-randconfig-073-20260706
> compiler: clang-22
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m=
 32G
>=20
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>=20
>=20
>=20
> If you fix the issue in a separate patch/commit (i.e. not just a new ve=
rsion of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email protected]>
> | Closes: https://lore.kernel.org/oe-lkp/202607142131.f70bbad3-lkp@inte=
l.com
>=20
>=20
>=20
> [    7.170805][    T1] ------------[ cut here ]------------
> [    7.173964][    T1] ext->ref.ct
> [    7.173973][    T1] WARNING: mm/slub.c:2085 at mark_obj_codetag_empt=
y+0x12d/0x180, CPU#1: swapper/0/1
> [    7.180958][    T1] Modules linked in:
> [    7.183435][    T1] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Tainted: G =
               T   7.2.0-rc1+ #1 PREEMPTLAZY
> [    7.198751][    T1] Tainted: [T]=3DRANDSTRUCT
> [    7.200585][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, =
1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
> [    7.204811][    T1] RIP: 0010:mark_obj_codetag_empty (slub.c:2079 (d=
iscriminator 256))
> [    7.206959][    T1] Code: 31 c0 31 c9 31 ff 31 d2 31 f6 e9 6e e6 02 =
00 5b 41 5c 41 5d 41 5e 41 5f 5d 31 c0 31 c9 31 ff 31 d2 31 f6 c3 48 83 f=
8 01 74 cc <0f> 0b eb b4 89 de 41 0f b6 d7 48 c7 c7 d0 01 0f 87 e8 fd 56 =
87 01
> All code
> =3D=3D=3D=3D=3D=3D=3D=3D
>    0:	31 c0                	xor    %eax,%eax
>    2:	31 c9                	xor    %ecx,%ecx
>    4:	31 ff                	xor    %edi,%edi
>    6:	31 d2                	xor    %edx,%edx
>    8:	31 f6                	xor    %esi,%esi
>    a:	e9 6e e6 02 00       	jmp    0x2e67d
>    f:	5b                   	pop    %rbx
>   10:	41 5c                	pop    %r12
>   12:	41 5d                	pop    %r13
>   14:	41 5e                	pop    %r14
>   16:	41 5f                	pop    %r15
>   18:	5d                   	pop    %rbp
>   19:	31 c0                	xor    %eax,%eax
>   1b:	31 c9                	xor    %ecx,%ecx
>   1d:	31 ff                	xor    %edi,%edi
>   1f:	31 d2                	xor    %edx,%edx
>   21:	31 f6                	xor    %esi,%esi
>   23:	c3                   	ret
>   24:	48 83 f8 01          	cmp    $0x1,%rax
>   28:	74 cc                	je     0xfffffffffffffff6
>   2a:*	0f 0b                	ud2		<-- trapping instruction
>   2c:	eb b4                	jmp    0xffffffffffffffe2
>   2e:	89 de                	mov    %ebx,%esi
>   30:	41 0f b6 d7          	movzbl %r15b,%edx
>   34:	48 c7 c7 d0 01 0f 87 	mov    $0xffffffff870f01d0,%rdi
>   3b:	e8 fd 56 87 01       	call   0x187573d
>=20
> Code starting with the faulting instruction
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>    0:	0f 0b                	ud2
>    2:	eb b4                	jmp    0xffffffffffffffb8
>    4:	89 de                	mov    %ebx,%esi
>    6:	41 0f b6 d7          	movzbl %r15b,%edx
>    a:	48 c7 c7 d0 01 0f 87 	mov    $0xffffffff870f01d0,%rdi
>   11:	e8 fd 56 87 01       	call   0x1875713
> [    7.216881][    T1] RSP: 0000:ffffc9000001f700 EFLAGS: 00010282
> [    7.218936][    T1] RAX: ffffffff87f3cc38 RBX: 0000000000000800 RCX:=
 000000000000000a
> [    7.226952][    T1] RDX: ffffea0004151200 RSI: ffffea00041524c0 RDI:=
 ffff888105448800
> [    7.229430][    T1] RBP: 0000000000000000 R08: 0000000000000000 R09:=
 0000000000000000
> [    7.232919][    T1] R10: 0000000000000000 R11: 0000000000000000 R12:=
 ffff888105448410
> [    7.236484][    T1] R13: ffffea0004151200 R14: 000000000000000a R15:=
 0000000000000a01
> [    7.238648][    T1] FS:  0000000000000000(0000) GS:ffff888795e7f000(=
0000) knlGS:0000000000000000
> [    7.241013][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003=
3
> [    7.242973][    T1] CR2: 0000000000000000 CR3: 0000000006b26000 CR4:=
 00000000000406f0
> [    7.245167][    T1] Call Trace:
> [    7.246092][    T1]  <TASK>
> [    7.246905][    T1]  __free_slab (slub.c:2244)
> [    7.248085][    T1]  ___cache_free (slub.c:6436 (discriminator 1))
> [    7.249275][    T1]  qlist_free_all (kasan/quarantine.c:163 (discrim=
inator 1) kasan/quarantine.c:179 (discriminator 1))
> [    7.250498][    T1]  kasan_quarantine_remove_cache (kasan/quarantine=
=2Ec:364)
> [    7.252073][    T1]  kmem_cache_shrink (slab_common.c:604)
> [    7.253337][    T1]  acpi_os_purge_cache (acpi/osl.c:1622)
> [    7.254628][    T1]  acpi_purge_cached_objects (acpi/acpica/utxface.=
c:237 (discriminator 512))
> [    7.256086][    T1]  acpi_initialize_objects (acpi/acpica/utxfinit.c=
:250)
> [    7.257334][    T1]  acpi_bus_init (acpi/bus.c:1503)
> [    7.258535][    T1]  ? acpi_init (bus.c:?)
> [    7.259714][    T1]  ? __kasan_kmalloc (kasan/common.c:398 kasan/com=
mon.c:415)
> [    7.261025][    T1]  ? __kmalloc_cache_noprof (linux/kasan.h:263 slu=
b.c:5474)
> [    7.262488][    T1]  ? kobject_init (linux/instrumented.h:97 linux/a=
tomic/atomic-instrumented.h:67 linux/refcount.h:134 linux/kref.h:31 kobje=
ct.c:201 kobject.c:352)
> [    7.263709][    T1]  ? kobject_create_and_add (kobject.c:798)
> [    7.265173][    T1]  acpi_init (acpi/bus.c:1592)
> [    7.266287][    T1]  do_one_initcall (main.c:1347)
> [    7.267461][    T1]  ? acpi_arch_init+0x40/0x40
> [    7.268701][    T1]  ? perf_trace_initcall_finish (main.c:?)
> [    7.270254][    T1]  ? do_raw_spin_lock (linux/instrumented.h:55 lin=
ux/atomic/atomic-instrumented.h:1301 asm-generic/qspinlock.h:111 locking/=
spinlock_debug.c:116)
> [    7.271619][    T1]  ? find_held_lock (locking/lockdep.c:5350)
> [    7.272891][    T1]  ? stack_depot_save_flags (stackdepot.c:728 (dis=
criminator 1))
> [    7.274356][    T1]  ? _raw_spin_unlock_irqrestore (linux/spinlock_a=
pi_smp.h:178 (discriminator 2))
> [    7.275877][    T1]  ? stack_depot_save_flags (stackdepot.c:728 (dis=
criminator 1))
> [    7.277336][    T1]  ? do_initcalls (linux/slab.h:985 linux/slab.h:1=
302 main.c:1418)
> [    7.278561][    T1]  ? kasan_save_track (kasan/common.c:58 kasan/com=
mon.c:78)
> [    7.280348][    T1]  ? kasan_save_track (kasan/common.c:57 kasan/com=
mon.c:78)
> [    7.288349][    T1]  ? __kasan_kmalloc (kasan/common.c:398 kasan/com=
mon.c:415)
> [    7.290315][    T1]  ? __kmalloc_noprof (linux/kasan.h:263 slub.c:53=
17 slub.c:5342)
> [    7.292347][    T1]  ? do_initcalls (linux/slab.h:985 linux/slab.h:1=
302 main.c:1418)
> [    7.294211][    T1]  ? kernel_init_freeable (main.c:1658)
> [    7.296477][    T1]  ? kernel_init (main.c:1548)
> [    7.298274][    T1]  ? ret_from_fork (x86/kernel/process.c:158)
> [    7.300206][    T1]  ? ret_from_fork_asm (x86/entry/entry_64.S:245)
> [    7.302217][    T1]  ? __lock_acquire (locking/lockdep.c:4674)
> [    7.307839][    T1]  ? _raw_spin_unlock_irqrestore (linux/spinlock_a=
pi_smp.h:178 (discriminator 2))
> [    7.310305][    T1]  ? parameq (linux/fortify-string.h:218 params.c:=
99)
> [    7.312115][    T1]  ? parse_args (params.c:153)
> [    7.314076][    T1]  ? lock_acquire (locking/lockdep.c:5868)
> [    7.316041][    T1]  ? local_trylock_acquire (linux/local_lock_inter=
nal.h:53)
> [    7.317915][    T1]  ? parameq (params.c:99)
> [    7.319735][    T1]  ? __kmalloc_noprof (linux/local_lock_internal.h=
:53)
> [    7.321920][    T1]  ? __kmalloc_noprof (linux/local_lock_internal.h=
:53)
> [    7.326225][    T1]  ? trace_kmalloc (trace/events/kmem.h:57 (discri=
minator 6))
> [    7.327722][    T1]  do_initcall_level (main.c:1409 (discriminator 1=
))
> [    7.329722][    T1]  do_initcalls (main.c:1425)
> [    7.331702][    T1]  ? kernel_init (main.c:1548)
> [    7.333605][    T1]  kernel_init_freeable (main.c:1658)
> [    7.335051][    T1]  ? rest_init (main.c:?)
> [    7.336248][    T1]  kernel_init (main.c:1548)
> [    7.337273][    T1]  ? rest_init (main.c:?)
> [    7.338461][    T1]  ret_from_fork (x86/kernel/process.c:158)
> [    7.339695][    T1]  ? exit_thread (x86/kernel/process.c:138)
> [    7.340878][    T1]  ? __switch_to (linux/instrumented.h:82 asm-gene=
ric/bitops/instrumented-non-atomic.h:141 linux/thread_info.h:133 linux/sc=
hed.h:2087 x86/include/asm/fpu/sched.h:34 x86/kernel/process_64.c:619)
> [    7.342110][    T1]  ? rest_init (main.c:?)
> [    7.343300][    T1]  ret_from_fork_asm (x86/entry/entry_64.S:245)
> [    7.344579][    T1]  </TASK>
> [    7.345444][    T1] irq event stamp: 29481
> [    7.346581][    T1] hardirqs last  enabled at (29495): __console_unl=
ock (printk/printk.c:347 (discriminator 3) printk/printk.c:2932 (discrimi=
nator 3))
> [    7.348686][    T1] hardirqs last disabled at (29510): __console_unl=
ock (printk/printk.c:345 (discriminator 6) printk/printk.c:2932 (discrimi=
nator 6))
> [    7.351184][    T1] softirqs last  enabled at (29232): handle_softir=
qs (softirq.c:468 (discriminator 2))
> [    7.353729][    T1] softirqs last disabled at (29227): __irq_exit_rc=
u (softirq.c:656 softirq.c:496 softirq.c:735)
> [    7.356197][    T1] ---[ end trace 0000000000000000 ]---
>=20
>=20
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20260714/202607142131.f70bbad3-=
[email protected]
>=20
>=20
>=20

--=20
Cheers,
Harry / Hyeonggon


--------------jUyNbDSOZ26IDnD3L0wPmVkN--

--------------wHkUIB4ELmmhRpV9tINOU1eM
Content-Type: application/pgp-signature; name="OpenPGP_signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="OpenPGP_signature.asc"

-----BEGIN PGP SIGNATURE-----

iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCalhBfwAKCRCGXBN6rc5S
1jnVAQDt5FamH3hO4DZzMBaYydNZuY94ty72o0UZZEFCD8OurwD+PXZpHEPdjRE0
1P+9kwgyaNF33tmh7/hBXJd9MpnApws=
=lXxv
-----END PGP SIGNATURE-----

--------------wHkUIB4ELmmhRpV9tINOU1eM--