[syzbot] [kernel?] general protection fault in psi_task_change

[syzbot <syzbot+66e09ade4298957334df@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    05441d697f7f Merge tag 'cocci-7.4-rc1' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1007668d580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1cf189394a856f11
dashboard link: https://syzkaller.appspot.com/bug?extid=66e09ade4298957334df
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=1422d381580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1407668d580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-05441d69.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0edd3964be19/vmlinux-05441d69.xz
kernel image: https://storage.googleapis.com/syzbot-assets/84d6d8dd5648/bzImage-05441d69.xz

AI-generated root cause summary:
In drivers/pci/proc.c, proc_bus_pci_write() allows writing directly to the PCI
configuration space of PCI devices including the host bridge (device 00:00.0).
Writing arbitrary data to host bridge configuration registers reconfigures
physical memory routing registers (such as PCIEXBAR, PAM, and TOLUD), causing
physical RAM regions backing kernel allocations (such as struct css_set) to
become unmapped and return all-ones (0xff). When the scheduler invokes
psi_task_change() -> task_psi_group() -> cgroup_psi(), reading cset->dfl_cgrp
from the affected memory yields 0xffffffffffffffff (-1), causing cgroup_ino() to
access an invalid offset that triggers a general protection fault and kernel
panic.

full analysis:  https://syzkaller.appspot.com/x/ai_root_cause?x=66e09ade4298957334df

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+66e09ade4298957334df@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000033: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000198-0x000000000000019f]
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:cgroup_ino include/linux/cgroup.h:724 [inline]
RIP: 0010:cgroup_psi include/linux/psi.h:39 [inline]
RIP: 0010:task_psi_group kernel/sched/psi.c:884 [inline]
RIP: 0010:task_psi_group kernel/sched/psi.c:880 [inline]
RIP: 0010:psi_task_change+0x20f/0x530 kernel/sched/psi.c:916
Code: 03 80 3c 02 00 0f 85 ff 02 00 00 4d 8b bd 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bf a0 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 02 00 00 4d 8b af a0 01 00 00 48 ba 00 00 00
RSP: 0018:ffffc900006a0c68 EFLAGS: 00010007
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000033 RSI: ffffffff8e60120c RDI: 000000000000019f
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff888054570000 R14: 0000000000000001 R15: ffffffffffffffff
FS:  0000000000000000(0000) GS:ffff8880d457c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5894989140 CR3: 00000000372ab000 CR4: 0000000000352ef0
Call Trace:
 <IRQ>
 psi_enqueue kernel/sched/stats.h:159 [inline]
 enqueue_task+0x1dc/0x4f0 kernel/sched/core.c:2199
 activate_task kernel/sched/core.c:2237 [inline]
 ttwu_do_activate+0x174/0x800 kernel/sched/core.c:3897
 ttwu_queue kernel/sched/core.c:4150 [inline]
 try_to_wake_up+0xce0/0x1ca0 kernel/sched/core.c:4488
 hrtimer_wakeup+0x47/0x60 kernel/time/hrtimer.c:2335
 __run_hrtimer kernel/time/hrtimer.c:2079 [inline]
 __hrtimer_run_queues+0x448/0x9a0 kernel/time/hrtimer.c:2136
 hrtimer_interrupt+0x441/0xaa0 kernel/time/hrtimer.c:2255
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: 67 a1 02 e9 43 61 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d c3 7d 1d 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000177e00 EFLAGS: 00000206
RAX: 000000000003cdf9 RBX: ffff88802069a580 RCX: ffffffff8bee4325
RDX: 0000000000000001 RSI: ffffffff8e628221 RDI: ffffffff8c835380
RBP: ffffed10040d34b0 R08: 0000000000000001 R09: ffffed100d426825
R10: ffff88806a13412b R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 1ffff9200002efc4 R15: dffffc0000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
 default_idle+0x9/0x10 arch/x86/kernel/process.c:768
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x3ae/0x5b0 kernel/sched/idle.c:355
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:458
 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x158
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:cgroup_ino include/linux/cgroup.h:724 [inline]
RIP: 0010:cgroup_psi include/linux/psi.h:39 [inline]
RIP: 0010:task_psi_group kernel/sched/psi.c:884 [inline]
RIP: 0010:task_psi_group kernel/sched/psi.c:880 [inline]
RIP: 0010:psi_task_change+0x20f/0x530 kernel/sched/psi.c:916
Code: 03 80 3c 02 00 0f 85 ff 02 00 00 4d 8b bd 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bf a0 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 02 00 00 4d 8b af a0 01 00 00 48 ba 00 00 00
RSP: 0018:ffffc900006a0c68 EFLAGS: 00010007
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000033 RSI: ffffffff8e60120c RDI: 000000000000019f
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff888054570000 R14: 0000000000000001 R15: ffffffffffffffff
FS:  0000000000000000(0000) GS:ffff8880d457c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5894989140 CR3: 00000000372ab000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	03 80 3c 02 00 0f    	add    0xf00023c(%rax),%eax
   6:	85 ff                	test   %edi,%edi
   8:	02 00                	add    (%rax),%al
   a:	00 4d 8b             	add    %cl,-0x75(%rbp)
   d:	bd 88 00 00 00       	mov    $0x88,%ebp
  12:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  19:	fc ff df
  1c:	49 8d bf a0 01 00 00 	lea    0x1a0(%r15),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 e0 02 00 00    	jne    0x314
  34:	4d 8b af a0 01 00 00 	mov    0x1a0(%r15),%r13
  3b:	48                   	rex.W
  3c:	ba                   	.byte 0xba
  3d:	00 00                	add    %al,(%rax)


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