syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

read-write to 0xffff888237c1ae54 of 4 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x70/0x460 kernel/time/hrtimer.c:1865
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 kcsan_setup_watchpoint+0x415/0x430 kernel/kcsan/core.c:705
 __rb_insert lib/rbtree.c:110 [inline]
 rb_insert_color+0x71/0x2b0 lib/rbtree.c:436
 kernfs_link_sibling+0x1a1/0x290 fs/kernfs/dir.c:391
 kernfs_add_one+0x13c/0x280 fs/kernfs/dir.c:810
 __kernfs_create_file+0x145/0x180 fs/kernfs/file.c:1067
 sysfs_add_file_mode_ns+0x132/0x1c0 fs/sysfs/file.c:319
 create_files fs/sysfs/group.c:76 [inline]
 internal_create_group+0x441/0x9e0 fs/sysfs/group.c:183
 sysfs_create_group+0x1f/0x30 fs/sysfs/group.c:209
 sysfs_slab_add+0x14d/0x290 mm/slub.c:7522
 do_kmem_cache_create+0x3c8/0x530 mm/slub.c:6470
 create_cache mm/slab_common.c:239 [inline]
 __kmem_cache_create_args+0x148/0x270 mm/slab_common.c:337
 kmem_cache_create_usercopy include/linux/slab.h:387 [inline]
 p9_client_create+0x8e5/0xbc0 net/9p/client.c:1051
 v9fs_session_init+0xf7/0xde0 fs/9p/v9fs.c:410
 v9fs_mount+0x67/0x590 fs/9p/vfs_super.c:122
 legacy_get_tree+0x75/0xd0 fs/fs_context.c:662
 vfs_get_tree+0x54/0x1d0 fs/super.c:1759
 do_new_mount+0x207/0x680 fs/namespace.c:3884
 path_mount+0x4a4/0xb20 fs/namespace.c:4211
 do_mount fs/namespace.c:4224 [inline]
 __do_sys_mount fs/namespace.c:4435 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4412
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4412
 x64_sys_call+0xd36/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c1ae54 of 4 bytes by task 5911 on cpu 1:
 print_cpu+0x359/0x680 kernel/time/timer_list.c:135
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
 seq_read_iter+0x627/0x940 fs/seq_file.c:272
 proc_reg_read_iter+0x10d/0x180 fs/proc/inode.c:299
 copy_splice_read+0x3c1/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x640 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1415
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00042a85 -> 0x00042a8a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5911 Comm: syz.4.931 Not tainted 6.15.0-rc5-syzkaller-00136-g9c69f8884904 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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