==================================================================
BUG: KASAN: out-of-bounds in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: out-of-bounds in atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
BUG: KASAN: out-of-bounds in put_bh include/linux/buffer_head.h:304 [inline]
BUG: KASAN: out-of-bounds in end_buffer_read_sync+0xc3/0xe0 fs/buffer.c:161
Write of size 4 at addr ffffc9000bc7f720 by task swapper/0/0

CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.15.0-rc6-syzkaller-00051-g405e6c37c89e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xb4/0x290 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x29a/0x2b0 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
 put_bh include/linux/buffer_head.h:304 [inline]
 end_buffer_read_sync+0xc3/0xe0 fs/buffer.c:161
 end_bio_bh_io_sync+0xbd/0x120 fs/buffer.c:2781
 blk_update_request+0x5ee/0xe80 block/blk-mq.c:983
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1145
 blk_complete_reqs block/blk-mq.c:1220 [inline]
 blk_done_softirq+0x10a/0x160 block/blk-mq.c:1225
 handle_softirqs+0x286/0x870 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
 sysvec_call_function_single+0xa3/0xc0 arch/x86/kernel/smp.c:266
 </IRQ>
 <TASK>
 asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:709
RIP: 0010:sched_core_balance+0x156/0xf00 kernel/sched/core.c:6413
Code: 51 6a 8b e8 1c 43 0b 00 4c 89 74 24 68 4c 89 7c 24 48 e9 3b 0d 00 00 4c 89 f7 e8 35 a2 c5 09 e8 90 47 34 00 fb 48 8b 5c 24 70 <83> fb 08 0f 83 06 0d 00 00 4c 8d 34 dd 20 fc 96 8d 4c 89 f0 48 c1
RSP: 0018:ffffffff8dc07980 EFLAGS: 00000282
RAX: 4f36f7e216f87200 RBX: 0000000000000000 RCX: 4f36f7e216f87200
RDX: 0000000000000000 RSI: ffffffff8d74c03c RDI: ffffffff8bc1d820
RBP: ffffffff8dc07ae8 R08: ffffffff8f7efb77 R09: 1ffffffff1efdf6e
R10: dffffc0000000000 R11: fffffbfff1efdf6f R12: ffff8880b8839b40
R13: dffffc0000000000 R14: ffff8880b8839b40 R15: 0000000000000000
 do_balance_callbacks kernel/sched/core.c:5028 [inline]
 __balance_callbacks kernel/sched/core.c:5082 [inline]
 finish_lock_switch kernel/sched/core.c:5129 [inline]
 finish_task_switch+0x3a7/0x950 kernel/sched/core.c:5248
 context_switch kernel/sched/core.c:5385 [inline]
 __schedule+0x16ea/0x4cd0 kernel/sched/core.c:6767
 schedule_idle+0x52/0x90 kernel/sched/core.c:6886
 do_idle+0x4ad/0x510 kernel/sched/idle.c:353
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:423
 rest_init+0x2de/0x300 init/main.c:743
 start_kernel+0x470/0x4f0 init/main.c:1099
 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:513
 x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:494
 common_startup_64+0x13e/0x147
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc9000bc78000, ffffc9000bc81000) created by:
 copy_process+0x544/0x3b80 kernel/fork.c:2259

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88807e4eee00 pfn:0x78362
memcg:ffff88801f376502
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff88807e4eee00 0000000000000000 00000001ffffffff ffff88801f376502
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 5489, tgid 5489 (dhcpcd), ts 130423291612, free_ts 130010177358
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x21ce/0x22b0 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2301
 alloc_frozen_pages_noprof mm/mempolicy.c:2372 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2392
 vm_area_alloc_pages mm/vmalloc.c:3592 [inline]
 __vmalloc_area_node mm/vmalloc.c:3670 [inline]
 __vmalloc_node_range_noprof+0x8fe/0x12c0 mm/vmalloc.c:3845
 __vmalloc_node_noprof+0x7d/0x90 mm/vmalloc.c:3908
 alloc_thread_stack_node kernel/fork.c:314 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:1136
 copy_process+0x544/0x3b80 kernel/fork.c:2259
 kernel_clone+0x21e/0x870 kernel/fork.c:2844
 __do_sys_clone kernel/fork.c:2987 [inline]
 __se_sys_clone kernel/fork.c:2971 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2971
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6347 tgid 6344 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0xb0e/0xcd0 mm/page_alloc.c:2725
 mm_free_pgd kernel/fork.c:793 [inline]
 __mmdrop+0xb5/0x460 kernel/fork.c:939
 exit_mm+0x1da/0x2c0 kernel/exit.c:589
 do_exit+0x859/0x2550 kernel/exit.c:940
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x95/0x780 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x8b/0x120 kernel/entry/common.c:218
 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc9000bc7f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000bc7f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000bc7f700: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
                                  ^
 ffffc9000bc7f780: 00 f2 f2 f2 00 00 00 f3 f3 f3 f3 f3 00 00 00 00
 ffffc9000bc7f800: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
==================================================================
----------------
Code disassembly (best guess):
   0:	51                   	push   %rcx
   1:	6a 8b                	push   $0xffffffffffffff8b
   3:	e8 1c 43 0b 00       	call   0xb4324
   8:	4c 89 74 24 68       	mov    %r14,0x68(%rsp)
   d:	4c 89 7c 24 48       	mov    %r15,0x48(%rsp)
  12:	e9 3b 0d 00 00       	jmp    0xd52
  17:	4c 89 f7             	mov    %r14,%rdi
  1a:	e8 35 a2 c5 09       	call   0x9c5a254
  1f:	e8 90 47 34 00       	call   0x3447b4
  24:	fb                   	sti
  25:	48 8b 5c 24 70       	mov    0x70(%rsp),%rbx
* 2a:	83 fb 08             	cmp    $0x8,%ebx <-- trapping instruction
  2d:	0f 83 06 0d 00 00    	jae    0xd39
  33:	4c 8d 34 dd 20 fc 96 	lea    -0x726903e0(,%rbx,8),%r14
  3a:	8d
  3b:	4c 89 f0             	mov    %r14,%rax
  3e:	48                   	rex.W
  3f:	c1                   	.byte 0xc1