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([2601:600:947f:f020:85dc:d2b2:c5ee:e3c4]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8971cd8b330sm146306406d6.29.2026.02.15.21.57.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 15 Feb 2026 21:57:38 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <544a0eb5-3c03-463b-911b-6f3b8037f8e1@redhat.com> Date: Mon, 16 Feb 2026 00:57:37 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [cgroups?] general protection fault in rebuild_sched_domains_locked To: syzbot , cgroups@vger.kernel.org, chenridong@huaweicloud.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, mkoutny@suse.com, syzkaller-bugs@googlegroups.com, tj@kernel.org References: <6992351f.050a0220.2757fb.0035.GAE@google.com> Content-Language: en-US In-Reply-To: <6992351f.050a0220.2757fb.0035.GAE@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2/15/26 4:05 PM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 37a93dd5c49b Merge tag 'net-next-7.0' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1649d073980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a512b4a06724b76a > dashboard link: https://syzkaller.appspot.com/bug?extid=460792609a79c085f79f > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=152086e6580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=139c2eef980000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/0dedaafff2ad/disk-37a93dd5.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/aa7fae081497/vmlinux-37a93dd5.xz > kernel image: https://storage.googleapis.com/syzbot-assets/9096b39b53e1/bzImage-37a93dd5.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+460792609a79c085f79f@syzkaller.appspotmail.com > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > R13: 00007fe00de15fac R14: 00007fe00de15fa0 R15: 00007fe00de15fa0 > > Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > CPU: 1 UID: 0 PID: 5994 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 > RIP: 0010:bitmap_subset include/linux/bitmap.h:433 [inline] > RIP: 0010:cpumask_subset include/linux/cpumask.h:836 [inline] > RIP: 0010:rebuild_sched_domains_locked+0x2aa/0x980 kernel/cgroup/cpuset.c:967 > Code: 7d 05 00 41 83 c4 01 89 de 48 83 c5 08 44 89 e7 e8 fb 76 05 00 41 39 dc 0f 8d 4c 04 00 00 e8 fd 7c 05 00 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 1d 06 00 00 48 8b 04 24 48 23 45 00 31 ff 44 > RSP: 0018:ffffc90003ecfbc0 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000020 > RDX: ffff888028de0000 RSI: ffffffff8200f003 RDI: ffffffff8df14f28 > RBP: 0000000000000000 R08: 0000000000000cc0 R09: 00000000ffffffff > R10: ffffffff8e7d95b3 R11: 0000000000000001 R12: 0000000000000000 > R13: 00000000000f4240 R14: dffffc0000000000 R15: 0000000000000000 > FS: 000055555c694500(0000) GS:ffff8881246a5000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000001b2f463fff CR3: 000000003704c000 CR4: 00000000003526f0 > Call Trace: > > rebuild_sched_domains_cpuslocked kernel/cgroup/cpuset.c:983 [inline] > rebuild_sched_domains+0x21/0x40 kernel/cgroup/cpuset.c:990 > sched_rt_handler+0xb5/0xe0 kernel/sched/rt.c:2911 > proc_sys_call_handler+0x47f/0x5a0 fs/proc/proc_sysctl.c:600 > new_sync_write fs/read_write.c:595 [inline] > vfs_write+0x6ac/0x1070 fs/read_write.c:688 > ksys_write+0x12a/0x250 fs/read_write.c:740 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7fe00db9bf79 > Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fff27bcda88 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 00007fe00de15fa0 RCX: 00007fe00db9bf79 > RDX: 00000000000000f6 RSI: 0000200000000000 RDI: 0000000000000003 > RBP: 00007fff27bcdaf0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > R13: 00007fe00de15fac R14: 00007fe00de15fa0 R15: 00007fe00de15fa0 > > Modules linked in: > ---[ end trace 0000000000000000 ]--- > RIP: 0010:bitmap_subset include/linux/bitmap.h:433 [inline] > RIP: 0010:cpumask_subset include/linux/cpumask.h:836 [inline] > RIP: 0010:rebuild_sched_domains_locked+0x2aa/0x980 kernel/cgroup/cpuset.c:967 > Code: 7d 05 00 41 83 c4 01 89 de 48 83 c5 08 44 89 e7 e8 fb 76 05 00 41 39 dc 0f 8d 4c 04 00 00 e8 fd 7c 05 00 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 1d 06 00 00 48 8b 04 24 48 23 45 00 31 ff 44 > RSP: 0018:ffffc90003ecfbc0 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000020 > RDX: ffff888028de0000 RSI: ffffffff8200f003 RDI: ffffffff8df14f28 > RBP: 0000000000000000 R08: 0000000000000cc0 R09: 00000000ffffffff > R10: ffffffff8e7d95b3 R11: 0000000000000001 R12: 0000000000000000 > R13: 00000000000f4240 R14: dffffc0000000000 R15: 0000000000000000 > FS: 000055555c694500(0000) GS:ffff8881246a5000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000001b2f463fff CR3: 000000003704c000 CR4: 00000000003526f0 > ---------------- > Code disassembly (best guess), 1 bytes skipped: > 0: 05 00 41 83 c4 add $0xc4834100,%eax > 5: 01 89 de 48 83 c5 add %ecx,-0x3a7cb722(%rcx) > b: 08 44 89 e7 or %al,-0x19(%rcx,%rcx,4) > f: e8 fb 76 05 00 call 0x5770f > 14: 41 39 dc cmp %ebx,%r12d > 17: 0f 8d 4c 04 00 00 jge 0x469 > 1d: e8 fd 7c 05 00 call 0x57d1f > 22: 48 89 e8 mov %rbp,%rax > 25: 48 c1 e8 03 shr $0x3,%rax > * 29: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction > 2e: 0f 85 1d 06 00 00 jne 0x651 > 34: 48 8b 04 24 mov (%rsp),%rax > 38: 48 23 45 00 and 0x0(%rbp),%rax > 3c: 31 ff xor %edi,%edi > 3e: 44 rex.R The cpuset.c:967 is:     966         for (i = 0; i < ndoms; ++i) {     967                 if (WARN_ON_ONCE(!cpumask_subset(doms[i], cpu_active_mask)))     968                         return; The oops was caused by accessing doms[i] which was kmalloc'ed in generate_sched_domains() by calling alloc_sched_domains() in kernel/sched/topology.c. Looking at the console log just before the oops, I saw [  124.398850][ T5994] FAULT_INJECTION: forcing a failure. [  124.398850][ T5994] name failslab, interval 1, probability 0, space 0, times 1 [  124.434865][ T5994] CPU: 1 UID: 0 PID: 5994 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) [  124.434909][ T5994] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 [  124.434936][ T5994] Call Trace: [  124.434947][ T5994]  [  124.434959][ T5994]  dump_stack_lvl+0x100/0x190 [  124.435026][ T5994]  should_fail_ex.cold+0x5/0xa [  124.435062][ T5994]  ? rebuild_sched_domains_locked+0x51/0x980 [  124.435113][ T5994]  should_failslab+0xc2/0x120 [  124.435153][ T5994]  __kmalloc_noprof+0xe0/0x850 [  124.435195][ T5994]  rebuild_sched_domains_locked+0x51/0x980 [  124.435266][ T5994]  rebuild_sched_domains+0x21/0x40 [  124.435314][ T5994]  sched_rt_handler+0xb5/0xe0 [  124.435359][ T5994]  proc_sys_call_handler+0x47f/0x5a0 [  124.435413][ T5994]  ? __pfx_proc_sys_call_handler+0x10/0x10 [  124.435475][ T5994]  vfs_write+0x6ac/0x1070 [  124.435511][ T5994]  ? __pfx_proc_sys_write+0x10/0x10 [  124.435562][ T5994]  ? __pfx_vfs_write+0x10/0x10 [  124.435597][ T5994]  ? __pfx_do_sys_openat2+0x10/0x10 [  124.435664][ T5994]  ksys_write+0x12a/0x250 [  124.435696][ T5994]  ? __pfx_ksys_write+0x10/0x10 [  124.435730][ T5994]  ? do_user_addr_fault+0x8d6/0x12f0 [  124.435787][ T5994]  do_syscall_64+0x106/0xf80 [  124.435834][ T5994]  ? clear_bhb_loop+0x40/0x90 [  124.435875][ T5994]  entry_SYSCALL_64_after_hwframe+0x77/0x7f So it looks like the oops may be expected. It may not be a bug in the cpuset AFAICS. Cheers, Longman