name failslab, interval 1, probability 0, space 0, times 0 CPU: 1 UID: 0 PID: 15955 Comm: syz.4.3814 Tainted: G W syzkaller #0 PREEMPT(voluntary) ================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff86874a00 of 8 bytes by task 15935 on cpu 0: data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130 prb_reserve+0x964/0xb60 kernel/printk/printk_ringbuffer.c:1724 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2451 blk_add_partition block/partitions/core.c:540 [inline] blk_add_partitions block/partitions/core.c:633 [inline] bdev_disk_changed+0x821/0xcb0 block/partitions/core.c:693 loop_reread_partitions drivers/block/loop.c:449 [inline] loop_set_status+0x5d2/0x6a0 drivers/block/loop.c:1278 loop_set_status64 drivers/block/loop.c:1374 [inline] lo_ioctl+0x671/0x12b0 drivers/block/loop.c:1560 blkdev_ioctl+0x37d/0x460 block/ioctl.c:707 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583 x64_sys_call+0x14b0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff86874a00 of 8 bytes by task 15955 on cpu 1: desc_read kernel/printk/printk_ringbuffer.c:496 [inline] desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline] desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline] prb_reserve+0x249/0xb60 kernel/printk/printk_ringbuffer.c:1674 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2451 dump_stack_print_info+0x183/0x1b0 lib/dump_stack.c:68 __dump_stack+0x11/0x30 lib/dump_stack.c:93 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_failslab+0x8c/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4901 [inline] slab_alloc_node mm/slub.c:5234 [inline] __do_kmalloc_node mm/slub.c:5651 [inline] __kmalloc_noprof+0xb9/0x5a0 mm/slub.c:5664 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] copy_splice_read+0xc2/0x660 fs/splice.c:337 do_splice_read fs/splice.c:981 [inline] splice_direct_to_actor+0x290/0x680 fs/splice.c:1086 do_splice_direct_actor fs/splice.c:1204 [inline] do_splice_direct+0xda/0x150 fs/splice.c:1230 do_sendfile+0x380/0x650 fs/read_write.c:1370 __do_sys_sendfile64 fs/read_write.c:1431 [inline] __se_sys_sendfile64 fs/read_write.c:1417 [inline] __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0xfffffffffffe8020 -> 0x00000000000938f0 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 15955 Comm: syz.4.3814 Tainted: G W syzkaller #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 ================================================================== Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: __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 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_failslab+0x8c/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4901 [inline] slab_alloc_node mm/slub.c:5234 [inline] __do_kmalloc_node mm/slub.c:5651 [inline] __kmalloc_noprof+0xb9/0x5a0 mm/slub.c:5664 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] copy_splice_read+0xc2/0x660 fs/splice.c:337 do_splice_read fs/splice.c:981 [inline] splice_direct_to_actor+0x290/0x680 fs/splice.c:1086 do_splice_direct_actor fs/splice.c:1204 [inline] do_splice_direct+0xda/0x150 fs/splice.c:1230 do_sendfile+0x380/0x650 fs/read_write.c:1370 __do_sys_sendfile64 fs/read_write.c:1431 [inline] __se_sys_sendfile64 fs/read_write.c:1417 [inline] __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f932b5ff749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f932a067038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f932b855fa0 RCX: 00007f932b5ff749 RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005 RBP: 00007f932a067090 R08: 0000000000000000 R09: 0000000000000000 R10: 00008000fffffffc R11: 0000000000000246 R12: 0000000000000001 R13: 00007f932b856038 R14: 00007f932b855fa0 R15: 00007ffee93fb068