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+0x95/0xd0 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 ================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff8687baa8 of 8 bytes by task 20689 on cpu 0: data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130 prb_reserve+0x8d7/0xad0 kernel/printk/printk_ringbuffer.c:1724 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x5c0 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 __ext4_msg+0x18f/0x1a0 fs/ext4/super.c:990 ext4_orphan_cleanup+0x8e2/0xa00 fs/ext4/orphan.c:492 __ext4_fill_super fs/ext4/super.c:5658 [inline] ext4_fill_super+0x3411/0x37a0 fs/ext4/super.c:5777 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691 get_tree_bdev+0x1f/0x30 fs/super.c:1714 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5809 vfs_get_tree+0x57/0x1d0 fs/super.c:1751 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3636 [inline] do_new_mount+0x24d/0x6a0 fs/namespace.c:3712 path_mount+0x4ab/0xb80 fs/namespace.c:4022 do_mount fs/namespace.c:4035 [inline] __do_sys_mount fs/namespace.c:4224 [inline] __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff8687baa8 of 8 bytes by task 20701 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+0x207/0xad0 kernel/printk/printk_ringbuffer.c:1674 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x5c0 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 printk_stack_address arch/x86/kernel/dumpstack.c:70 [inline] __show_trace_log_lvl+0x4e3/0x560 arch/x86/kernel/dumpstack.c:282 __dump_stack+0x1d/0x30 lib/dump_stack.c:94 dump_stack_lvl+0x95/0xd0 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_fail_alloc_page+0xf2/0x100 mm/fail_page_alloc.c:44 prepare_alloc_pages mm/page_alloc.c:4985 [inline] __alloc_frozen_pages_noprof+0x109/0x360 mm/page_alloc.c:5199 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2486 folio_alloc_mpol_noprof+0x39/0x80 mm/mempolicy.c:2505 shmem_alloc_folio mm/shmem.c:1890 [inline] shmem_alloc_and_add_folio mm/shmem.c:1932 [inline] shmem_get_folio_gfp+0x3cf/0xd50 mm/shmem.c:2556 shmem_get_folio mm/shmem.c:2662 [inline] shmem_write_begin+0xfc/0x1f0 mm/shmem.c:3315 generic_perform_write+0x184/0x490 mm/filemap.c:4314 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3490 do_iter_readv_writev+0x4a1/0x540 fs/read_write.c:-1 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057 do_pwritev fs/read_write.c:1153 [inline] __do_sys_pwritev2 fs/read_write.c:1211 [inline] __se_sys_pwritev2+0xfc/0x1c0 fs/read_write.c:1202 __x64_sys_pwritev2+0x67/0x80 fs/read_write.c:1202 x64_sys_call+0x2c9e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:329 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000000000d80 -> 0x00000000000b0510 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 20701 Comm: syz.1.5580 Tainted: G W syzkaller #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 ================================================================== fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_fail_alloc_page+0xf2/0x100 mm/fail_page_alloc.c:44 prepare_alloc_pages mm/page_alloc.c:4985 [inline] __alloc_frozen_pages_noprof+0x109/0x360 mm/page_alloc.c:5199 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2486 folio_alloc_mpol_noprof+0x39/0x80 mm/mempolicy.c:2505 shmem_alloc_folio mm/shmem.c:1890 [inline] shmem_alloc_and_add_folio mm/shmem.c:1932 [inline] shmem_get_folio_gfp+0x3cf/0xd50 mm/shmem.c:2556 shmem_get_folio mm/shmem.c:2662 [inline] shmem_write_begin+0xfc/0x1f0 mm/shmem.c:3315 generic_perform_write+0x184/0x490 mm/filemap.c:4314 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3490 do_iter_readv_writev+0x4a1/0x540 fs/read_write.c:-1 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057 do_pwritev fs/read_write.c:1153 [inline] __do_sys_pwritev2 fs/read_write.c:1211 [inline] __se_sys_pwritev2+0xfc/0x1c0 fs/read_write.c:1202 __x64_sys_pwritev2+0x67/0x80 fs/read_write.c:1202 x64_sys_call+0x2c9e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:329 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f241b93f749 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:00007f241a3a7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148 RAX: ffffffffffffffda RBX: 00007f241bb95fa0 RCX: 00007f241b93f749 RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000003 RBP: 00007f241a3a7090 R08: 0000000000000000 R09: 0000000000000003 R10: 0000000000002000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007f241bb96038 R14: 00007f241bb95fa0 R15: 00007ffd75e1caa8