Re: [syzbot] [io-uring?] WARNING: locking bug in sched_core_balance

Re: [syzbot] [io-uring?] WARNING: locking bug in sched_core_balance

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9b2ffa6148b1 Merge tag 'mtd/fixes-for-6.13-rc5' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10a00018580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d269ef41b9262400
dashboard link: https://syzkaller.appspot.com/bug?extid=14641d8d78cc029add8a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14ad74c4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/73bb7d109a64/disk-9b2ffa61.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/001f7910aa4e/vmlinux-9b2ffa61.xz
kernel image: https://storage.googleapis.com/syzbot-assets/11e525a24c33/bzImage-9b2ffa61.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+14641d8d78cc029add8a@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: fffffbfff3f8171b
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffe4067 P4D 23ffe4067 PUD 23ffe3067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc4-syzkaller-00012-g9b2ffa6148b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x82/0x290 mm/kasan/generic.c:189
Code: 01 00 00 00 00 fc ff df 4f 8d 3c 31 4c 89 fd 4c 29 dd 48 83 fd 10 7f 29 48 85 ed 0f 84 3e 01 00 00 4c 89 cd 48 f7 d5 48 01 dd <41> 80 3b 00 0f 85 c9 01 00 00 49 ff c3 48 ff c5 75 ee e9 1e 01 00
RSP: 0018:ffffffff8e607640 EFLAGS: 00010086
RAX: 000000000172ce01 RBX: 1ffffffff3f8171b RCX: ffffffff817ac1c4
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9fc0b8d8
RBP: ffffffffffffffff R08: ffffffff9fc0b8df R09: 1ffffffff3f8171b
R10: dffffc0000000000 R11: fffffbfff3f8171b R12: ffffffff8e697084
R13: ffffffff8e6965c0 R14: dffffc0000000001 R15: fffffbfff3f8171c
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff3f8171b CR3: 000000005d4e4000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 __lock_acquire+0xc94/0x2100 kernel/locking/lockdep.c:5196
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
 raw_spin_rq_lock_nested+0xb0/0x140 kernel/sched/core.c:606
 raw_spin_rq_lock kernel/sched/sched.h:1523 [inline]
 raw_spin_rq_lock_irq kernel/sched/sched.h:1529 [inline]
 sched_core_balance+0xd87/0xf50 kernel/sched/core.c:6411
 do_balance_callbacks kernel/sched/core.c:5021 [inline]
 __balance_callbacks+0x18a/0x280 kernel/sched/core.c:5075
 finish_lock_switch kernel/sched/core.c:5122 [inline]
 finish_task_switch+0x1d3/0x870 kernel/sched/core.c:5241
 context_switch kernel/sched/core.c:5372 [inline]
 __schedule+0x1858/0x4c30 kernel/sched/core.c:6756
 schedule_idle+0x56/0x90 kernel/sched/core.c:6874
 do_idle+0x567/0x5c0 kernel/sched/idle.c:353
 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423
 rest_init+0x2dc/0x300 init/main.c:747
 start_kernel+0x47f/0x500 init/main.c:1102
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x9f/0xa0 arch/x86/kernel/head64.c:488
 common_startup_64+0x13e/0x147
 </TASK>
Modules linked in:
CR2: fffffbfff3f8171b
---[ end trace 0000000000000000 ]---
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x82/0x290 mm/kasan/generic.c:189
Code: 01 00 00 00 00 fc ff df 4f 8d 3c 31 4c 89 fd 4c 29 dd 48 83 fd 10 7f 29 48 85 ed 0f 84 3e 01 00 00 4c 89 cd 48 f7 d5 48 01 dd <41> 80 3b 00 0f 85 c9 01 00 00 49 ff c3 48 ff c5 75 ee e9 1e 01 00
RSP: 0018:ffffffff8e607640 EFLAGS: 00010086
RAX: 000000000172ce01 RBX: 1ffffffff3f8171b RCX: ffffffff817ac1c4
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9fc0b8d8
RBP: ffffffffffffffff R08: ffffffff9fc0b8df R09: 1ffffffff3f8171b
R10: dffffc0000000000 R11: fffffbfff3f8171b R12: ffffffff8e697084
R13: ffffffff8e6965c0 R14: dffffc0000000001 R15: fffffbfff3f8171c
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff3f8171b CR3: 000000005d4e4000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess), 7 bytes skipped:
   0:	df 4f 8d             	fisttps -0x73(%rdi)
   3:	3c 31                	cmp    $0x31,%al
   5:	4c 89 fd             	mov    %r15,%rbp
   8:	4c 29 dd             	sub    %r11,%rbp
   b:	48 83 fd 10          	cmp    $0x10,%rbp
   f:	7f 29                	jg     0x3a
  11:	48 85 ed             	test   %rbp,%rbp
  14:	0f 84 3e 01 00 00    	je     0x158
  1a:	4c 89 cd             	mov    %r9,%rbp
  1d:	48 f7 d5             	not    %rbp
  20:	48 01 dd             	add    %rbx,%rbp
* 23:	41 80 3b 00          	cmpb   $0x0,(%r11) <-- trapping instruction
  27:	0f 85 c9 01 00 00    	jne    0x1f6
  2d:	49 ff c3             	inc    %r11
  30:	48 ff c5             	inc    %rbp
  33:	75 ee                	jne    0x23
  35:	e9                   	.byte 0xe9
  36:	1e                   	(bad)
  37:	01 00                	add    %eax,(%rax)


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [io-uring?] WARNING: locking bug in sched_core_balance

[Jens Axboe]

On 12/24/24 11:53 PM, syzbot wrote:
> syzbot has found a reproducer for the following issue on:

No indication that this is related to io_uring at all.

#syz set subsystems: kernel

-- 
Jens Axboe

Re: [syzbot] [kernel] WARNING: locking bug in sched_core_balance

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13c3d6df980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1c541fa8af5c9cc7
dashboard link: https://syzkaller.appspot.com/bug?extid=14641d8d78cc029add8a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=127f3818580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172306c4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0ebebb2cf79b/disk-ccb98cce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8da8041cbc40/vmlinux-ccb98cce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8de730af73c0/bzImage-ccb98cce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+14641d8d78cc029add8a@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: fffffbfff3f8171b
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffe4067 P4D 23ffe4067 PUD 23ffe3067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x82/0x290 mm/kasan/generic.c:189
Code: 01 00 00 00 00 fc ff df 4f 8d 3c 31 4c 89 fd 4c 29 dd 48 83 fd 10 7f 29 48 85 ed 0f 84 3e 01 00 00 4c 89 cd 48 f7 d5 48 01 dd <41> 80 3b 00 0f 85 c9 01 00 00 49 ff c3 48 ff c5 75 ee e9 1e 01 00
RSP: 0018:ffffffff8e607640 EFLAGS: 00010086
RAX: 000000000172ce01 RBX: 1ffffffff3f8171b RCX: ffffffff817ac174
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9fc0b8d8
RBP: ffffffffffffffff R08: ffffffff9fc0b8df R09: 1ffffffff3f8171b
R10: dffffc0000000000 R11: fffffbfff3f8171b R12: ffffffff8e697084
R13: ffffffff8e6965c0 R14: dffffc0000000001 R15: fffffbfff3f8171c
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff3f8171b CR3: 0000000077460000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 __lock_acquire+0xc94/0x2100 kernel/locking/lockdep.c:5196
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
 raw_spin_rq_lock_nested+0xb0/0x140 kernel/sched/core.c:606
 raw_spin_rq_lock kernel/sched/sched.h:1523 [inline]
 raw_spin_rq_lock_irq kernel/sched/sched.h:1529 [inline]
 sched_core_balance+0xd87/0xf50 kernel/sched/core.c:6411
 do_balance_callbacks kernel/sched/core.c:5021 [inline]
 __balance_callbacks+0x18a/0x280 kernel/sched/core.c:5075
 finish_lock_switch kernel/sched/core.c:5122 [inline]
 finish_task_switch+0x1d3/0x870 kernel/sched/core.c:5241
 context_switch kernel/sched/core.c:5372 [inline]
 __schedule+0x1858/0x4c30 kernel/sched/core.c:6756
 schedule_idle+0x56/0x90 kernel/sched/core.c:6874
 do_idle+0x567/0x5c0 kernel/sched/idle.c:353
 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423
 rest_init+0x2dc/0x300 init/main.c:747
 start_kernel+0x47f/0x500 init/main.c:1102
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x9f/0xa0 arch/x86/kernel/head64.c:488
 common_startup_64+0x13e/0x147
 </TASK>
Modules linked in:
CR2: fffffbfff3f8171b
---[ end trace 0000000000000000 ]---
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x82/0x290 mm/kasan/generic.c:189
Code: 01 00 00 00 00 fc ff df 4f 8d 3c 31 4c 89 fd 4c 29 dd 48 83 fd 10 7f 29 48 85 ed 0f 84 3e 01 00 00 4c 89 cd 48 f7 d5 48 01 dd <41> 80 3b 00 0f 85 c9 01 00 00 49 ff c3 48 ff c5 75 ee e9 1e 01 00
RSP: 0018:ffffffff8e607640 EFLAGS: 00010086
RAX: 000000000172ce01 RBX: 1ffffffff3f8171b RCX: ffffffff817ac174
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9fc0b8d8
RBP: ffffffffffffffff R08: ffffffff9fc0b8df R09: 1ffffffff3f8171b
R10: dffffc0000000000 R11: fffffbfff3f8171b R12: ffffffff8e697084
R13: ffffffff8e6965c0 R14: dffffc0000000001 R15: fffffbfff3f8171c
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff3f8171b CR3: 0000000077460000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess), 7 bytes skipped:
   0:	df 4f 8d             	fisttps -0x73(%rdi)
   3:	3c 31                	cmp    $0x31,%al
   5:	4c 89 fd             	mov    %r15,%rbp
   8:	4c 29 dd             	sub    %r11,%rbp
   b:	48 83 fd 10          	cmp    $0x10,%rbp
   f:	7f 29                	jg     0x3a
  11:	48 85 ed             	test   %rbp,%rbp
  14:	0f 84 3e 01 00 00    	je     0x158
  1a:	4c 89 cd             	mov    %r9,%rbp
  1d:	48 f7 d5             	not    %rbp
  20:	48 01 dd             	add    %rbx,%rbp
* 23:	41 80 3b 00          	cmpb   $0x0,(%r11) <-- trapping instruction
  27:	0f 85 c9 01 00 00    	jne    0x1f6
  2d:	49 ff c3             	inc    %r11
  30:	48 ff c5             	inc    %rbp
  33:	75 ee                	jne    0x23
  35:	e9                   	.byte 0xe9
  36:	1e                   	(bad)
  37:	01 00                	add    %eax,(%rax)


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [kernel] WARNING: locking bug in sched_core_balance

[syzbot]

syzbot has bisected this issue to:

commit 7908632f2927b65f7486ae6b67c24071666ba43f
Author: Maíra Canal <mcanal@igalia.com>
Date:   Thu Sep 14 10:19:02 2023 +0000

    Revert "drm/vkms: Fix race-condition between the hrtimer and the atomic commit"

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=111018b0580000
start commit:   ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=131018b0580000
console output: https://syzkaller.appspot.com/x/log.txt?x=151018b0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1c541fa8af5c9cc7
dashboard link: https://syzkaller.appspot.com/bug?extid=14641d8d78cc029add8a
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=127f3818580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172306c4580000

Reported-by: syzbot+14641d8d78cc029add8a@syzkaller.appspotmail.com
Fixes: 7908632f2927 ("Revert "drm/vkms: Fix race-condition between the hrtimer and the atomic commit"")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection