RBP: 00007ffd68502e9c R08: 0000000007860211 R09: 7fffffffffffffff R10: 3fffffffffffffff R11: 0000000000000202 R12: 0000000000001388 R13: 00000000000927c0 R14: 0000000000021677 R15: 00007ffd68502ef0 ================================================================== BUG: KCSAN: data-race in data_push_tail / vsnprintf write to 0xffffffff88e45460 of 1 bytes by task 8575 on cpu 1: vsnprintf+0x2ce/0x890 lib/vsprintf.c:2878 vscnprintf+0x41/0x90 lib/vsprintf.c:2991 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93 loop_set_size+0x2e/0x70 drivers/block/loop.c:210 loop_configure+0x8d3/0xa50 drivers/block/loop.c:1067 lo_ioctl+0x1e1/0x1350 drivers/block/loop.c:1523 blkdev_ioctl+0x34f/0x440 block/ioctl.c:705 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:584 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584 x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff88e45460 of 8 bytes by task 3302 on cpu 0: data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline] data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 __show_regs+0xf0/0x440 arch/x86/kernel/process_64.c:92 show_regs_if_on_stack arch/x86/kernel/dumpstack.c:165 [inline] show_trace_log_lvl+0x423/0x560 arch/x86/kernel/dumpstack.c:298 __dump_stack+0x1d/0x30 lib/dump_stack.c:94 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 dump_header+0x81/0x220 mm/oom_kill.c:467 oom_kill_process+0x342/0x400 mm/oom_kill.c:1040 out_of_memory+0x979/0xb80 mm/oom_kill.c:1178 mem_cgroup_out_of_memory mm/memcontrol.c:1649 [inline] mem_cgroup_oom mm/memcontrol.c:1672 [inline] try_charge_memcg+0x5e6/0x9e0 mm/memcontrol.c:2399 try_charge mm/memcontrol.c:2499 [inline] charge_memcg+0x51/0xc0 mm/memcontrol.c:4702 __mem_cgroup_charge+0x28/0xb0 mm/memcontrol.c:4719 mem_cgroup_charge include/linux/memcontrol.h:654 [inline] filemap_add_folio+0x4e/0x1b0 mm/filemap.c:964 __filemap_get_folio+0x31e/0x6b0 mm/filemap.c:1991 filemap_fault+0x41f/0xb40 mm/filemap.c:3455 __do_fault+0xbc/0x200 mm/memory.c:5152 do_read_fault mm/memory.c:5573 [inline] do_fault mm/memory.c:5707 [inline] do_pte_missing mm/memory.c:4234 [inline] handle_pte_fault mm/memory.c:6052 [inline] __handle_mm_fault mm/memory.c:6195 [inline] handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364 do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 value changed: 0x00000000fffff35b -> 0x00000000fffff30a Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 3302 Comm: syz-executor Not tainted 6.17.0-rc1-syzkaller-00004-g53e760d89498 #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 ================================================================== memory: usage 307200kB, limit 307200kB, failcnt 644 memory+swap: usage 308344kB, limit 9007199254740988kB, failcnt 0 kmem: usage 307184kB, limit 9007199254740988kB, failcnt 0 Memory cgroup stats for /syz1: cache 0 rss 0 shmem 0 mapped_file 0 dirty 0 writeback 0 workingset_refault_anon 2723 workingset_refault_file 1261 swap 1175552 swapcached 16384 pgpgin 91793 pgpgout 91789 pgfault 114381 pgmajfault 514 inactive_anon 4096 active_anon 12288 inactive_file 0 active_file 0 unevictable 0 hierarchical_memory_limit 314572800 hierarchical_memsw_limit 9223372036854771712 total_cache 0 total_rss 0 total_shmem 0 total_mapped_file 0 total_dirty 0 total_writeback 0 total_workingset_refault_anon 2723 total_workingset_refault_file 1261 total_swap 1175552 total_swapcached 16384 total_pgpgin 91793 total_pgpgout 91789 total_pgfault 114381 total_pgmajfault 514 total_inactive_anon 4096 total_active_anon 12288 total_inactive_file 0 total_active_file 0 total_unevictable 0 oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=/,mems_allowed=0,oom_memcg=/syz1,task_memcg=/syz1,task=syz.1.1878,pid=8550,uid=0 Memory cgroup out of memory: Killed process 8550 (syz.1.1878) total-vm:93764kB, anon-rss:1072kB, file-rss:22180kB, shmem-rss:128kB, UID:0 pgtables:152kB oom_score_adj:1000