From: kernel test robot <oliver.sang@intel.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: <oe-lkp@lists.linux.dev>, <lkp@intel.com>,
Axel Rasmussen <axelrasmussen@google.com>, <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>, <cgroups@vger.kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
<oliver.sang@intel.com>
Subject: Re: [PATCH 3/3] ptdesc: Account page tables to memcgs again
Date: Thu, 5 Mar 2026 15:00:34 +0800 [thread overview]
Message-ID: <202603051407.fde83fdb-lkp@intel.com> (raw)
In-Reply-To: <20260225162319.315281-4-willy@infradead.org>
Hello,
kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on:
commit: 1445ef3d5f2fefd1fcedb68cff3fff0a33994791 ("[PATCH 3/3] ptdesc: Account page tables to memcgs again")
url: https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/memcg-Add-memcg_stat_mod/20260226-003144
base: https://git.kernel.org/cgit/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/all/20260225162319.315281-4-willy@infradead.org/
patch subject: [PATCH 3/3] ptdesc: Account page tables to memcgs again
in testcase: boot
config: x86_64-randconfig-r052-20250414
compiler: gcc-14
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202603051407.fde83fdb-lkp@intel.com
[ 14.109191][ T1] BUG: kernel NULL pointer dereference, address: 0000000000000880
[ 14.109653][ T1] #PF: supervisor read access in kernel mode
[ 14.109989][ T1] #PF: error_code(0x0000) - not-present page
[ 14.110322][ T1] PGD 12a8ff067 P4D 12a8ff067 PUD 0
[ 14.110622][ T1] Oops: Oops: 0000 [#1] SMP
[ 14.110878][ T1] CPU: 0 UID: 0 PID: 1 Comm: systemd Not tainted 7.0.0-rc1-00154-g1445ef3d5f2f #1 PREEMPT(full)
[ 14.111462][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 14.112082][ T1] RIP: 0010:mem_cgroup_lruvec (include/linux/memcontrol.h:729 (discriminator 1))
[ 14.112396][ T1] Code: 74 09 48 8d 83 40 22 00 00 eb 1f 4d 85 e4 75 07 4c 8b 25 bd c3 1e 02 48 63 83 b8 1e 00 00 49 8b 84 c4 58 07 00 00 48 83 c0 40 <48> 39 98 40 08 00 00 74 07 48 89 98 40 08 00 00 5b 41 5c 5d c3 cc
All code
========
0: 74 09 je 0xb
2: 48 8d 83 40 22 00 00 lea 0x2240(%rbx),%rax
9: eb 1f jmp 0x2a
b: 4d 85 e4 test %r12,%r12
e: 75 07 jne 0x17
10: 4c 8b 25 bd c3 1e 02 mov 0x21ec3bd(%rip),%r12 # 0x21ec3d4
17: 48 63 83 b8 1e 00 00 movslq 0x1eb8(%rbx),%rax
1e: 49 8b 84 c4 58 07 00 mov 0x758(%r12,%rax,8),%rax
25: 00
26: 48 83 c0 40 add $0x40,%rax
2a:* 48 39 98 40 08 00 00 cmp %rbx,0x840(%rax) <-- trapping instruction
31: 74 07 je 0x3a
33: 48 89 98 40 08 00 00 mov %rbx,0x840(%rax)
3a: 5b pop %rbx
3b: 41 5c pop %r12
3d: 5d pop %rbp
3e: c3 ret
3f: cc int3
Code starting with the faulting instruction
===========================================
0: 48 39 98 40 08 00 00 cmp %rbx,0x840(%rax)
7: 74 07 je 0x10
9: 48 89 98 40 08 00 00 mov %rbx,0x840(%rax)
10: 5b pop %rbx
11: 41 5c pop %r12
13: 5d pop %rbp
14: c3 ret
15: cc int3
[ 14.113448][ T1] RSP: 0018:ffff888101467c10 EFLAGS: 00210202
[ 14.113783][ T1] RAX: 0000000000000040 RBX: ffffffff83708880 RCX: 0000000000000001
[ 14.114217][ T1] RDX: 0000000000000001 RSI: ffffffff83708880 RDI: ffff88812a845f82
[ 14.114652][ T1] RBP: ffff888101467c20 R08: 0000000000000000 R09: 0000000000000000
[ 14.115087][ T1] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88812a845f82
[ 14.115979][ T1] R13: ffff888105fdd3a8 R14: ffff888105fdd740 R15: ffff888101442000
[ 14.116421][ T1] FS: 0000000000000000(0000) GS:ffff88889bc98000(0063) knlGS:00000000f72f8840
[ 14.116911][ T1] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
[ 14.117276][ T1] CR2: 0000000000000880 CR3: 000000012b816000 CR4: 00000000000406f0
[ 14.117713][ T1] Call Trace:
[ 14.117901][ T1] <TASK>
[ 14.118070][ T1] memcg_stat_mod (mm/memcontrol.c:804)
[ 14.118328][ T1] __pagetable_ctor (include/linux/mm.h:3547)
[ 14.118595][ T1] pgd_alloc (include/asm-generic/pgalloc.h:291 arch/x86/mm/pgtable.c:314 arch/x86/mm/pgtable.c:328)
[ 14.118863][ T1] mm_init+0x210/0x390
[ 14.119129][ T1] dup_mm+0x45/0xe0
[ 14.119401][ T1] copy_process (kernel/fork.c:1587 (discriminator 1) kernel/fork.c:2228 (discriminator 1))
[ 14.119661][ T1] ? free_filename (fs/namei.c:148)
[ 14.119930][ T1] kernel_clone (include/linux/random.h:26 kernel/fork.c:2660)
[ 14.120200][ T1] __do_compat_sys_ia32_clone (arch/x86/kernel/sys_ia32.c:255)
[ 14.120519][ T1] __ia32_compat_sys_ia32_clone (arch/x86/kernel/sys_ia32.c:240)
[ 14.120837][ T1] ia32_sys_call (kbuild/obj/consumer/x86_64-randconfig-r052-20250414/./arch/x86/include/generated/asm/syscalls_32.h:121)
[ 14.121105][ T1] __do_fast_syscall_32 (arch/x86/entry/syscall_32.c:83 arch/x86/entry/syscall_32.c:307)
[ 14.121398][ T1] do_fast_syscall_32 (arch/x86/entry/syscall_32.c:332 (discriminator 1))
[ 14.121671][ T1] do_SYSENTER_32 (arch/x86/entry/syscall_32.c:371)
[ 14.121926][ T1] entry_SYSENTER_compat_after_hwframe (arch/x86/entry/entry_64_compat.S:127)
[ 14.122298][ T1] RIP: 0023:0xf7f9c38c
[ 14.122527][ T1] Code: d2 74 05 c1 e8 0c 89 02 8b 5d fc 31 c0 c9 c3 cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
All code
========
0: d2 74 05 c1 shlb %cl,-0x3f(%rbp,%rax,1)
4: e8 0c 89 02 8b call 0xffffffff8b028915
9: 5d pop %rbp
a: fc cld
b: 31 c0 xor %eax,%eax
d: c9 leave
e: c3 ret
f: cc int3
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: 90 nop
1c: 90 nop
1d: 90 nop
1e: 0f 1f 00 nopl (%rax)
21: 51 push %rcx
22: 52 push %rdx
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
2a:* 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 ret
2e: cc int3
2f: 90 nop
30: 90 nop
31: 90 nop
32: 90 nop
33: 90 nop
34: 90 nop
35: 90 nop
36: 90 nop
37: 90 nop
38: 90 nop
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 58 pop %rax
3f: b8 .byte 0xb8
Code starting with the faulting instruction
===========================================
0: 5d pop %rbp
1: 5a pop %rdx
2: 59 pop %rcx
3: c3 ret
4: cc int3
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 58 pop %rax
15: b8 .byte 0xb8
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260305/202603051407.fde83fdb-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
prev parent reply other threads:[~2026-03-05 7:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 16:22 [PATCH 0/3] Make memcg location more flexible Matthew Wilcox (Oracle)
2026-02-25 16:22 ` [PATCH 1/3] memcg: Add memcg_stat_mod() Matthew Wilcox (Oracle)
2026-02-25 19:22 ` Johannes Weiner
2026-02-25 16:22 ` [PATCH 2/3] memcg: Simplify mod_lruvec_kmem_state() Matthew Wilcox (Oracle)
2026-02-25 16:22 ` [PATCH 3/3] ptdesc: Account page tables to memcgs again Matthew Wilcox (Oracle)
2026-02-25 16:55 ` Shakeel Butt
2026-02-25 21:01 ` Matthew Wilcox
2026-02-26 0:00 ` Shakeel Butt
2026-02-25 20:57 ` Matthew Wilcox
2026-02-25 21:48 ` Axel Rasmussen
2026-03-05 7:00 ` kernel test robot [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202603051407.fde83fdb-lkp@intel.com \
--to=oliver.sang@intel.com \
--cc=axelrasmussen@google.com \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=linux-mm@kvack.org \
--cc=lkp@intel.com \
--cc=mhocko@kernel.org \
--cc=oe-lkp@lists.linux.dev \
--cc=roman.gushchin@linux.dev \
--cc=shakeel.butt@linux.dev \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.