should_fail_alloc_page+0xf2/0x100 mm/fail_page_alloc.c:44 prepare_alloc_pages mm/page_alloc.c:5002 [inline] __alloc_frozen_pages_noprof+0x108/0x350 mm/page_alloc.c:5215 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2490 ================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff86c714e8 of 8 bytes by task 19138 on cpu 1: data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130 prb_reserve+0x8d6/0xad0 kernel/printk/printk_ringbuffer.c:1727 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2504 __ext4_msg+0x1aa/0x1c0 fs/ext4/super.c:1001 ext4_fill_super+0x2f90/0x37c0 fs/ext4/super.c:5839 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694 get_tree_bdev+0x1f/0x30 fs/super.c:1717 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5856 vfs_get_tree+0x57/0x1d0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3758 [inline] do_new_mount+0x288/0x8d0 fs/namespace.c:3834 path_mount+0x4d0/0xbc0 fs/namespace.c:4154 do_mount fs/namespace.c:4167 [inline] __do_sys_mount fs/namespace.c:4383 [inline] __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4360 __x64_sys_mount+0x67/0x80 fs/namespace.c:4360 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff86c714e8 of 8 bytes by task 19140 on cpu 0: 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+0x216/0xad0 kernel/printk/printk_ringbuffer.c:1677 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2504 printk_stack_address arch/x86/kernel/dumpstack.c:70 [inline] __show_trace_log_lvl+0x460/0x560 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+0x263/0x280 lib/fault-inject.c:174 should_fail_alloc_page+0xf2/0x100 mm/fail_page_alloc.c:44 prepare_alloc_pages mm/page_alloc.c:5002 [inline] __alloc_frozen_pages_noprof+0x108/0x350 mm/page_alloc.c:5215 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2490 alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline] alloc_pages_noprof+0x8f/0x140 mm/mempolicy.c:2581 anon_pipe_get_page fs/pipe.c:124 [inline] anon_pipe_write+0x69c/0xb20 fs/pipe.c:515 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x5a6/0x9f0 fs/read_write.c:688 ksys_write+0xdc/0x1a0 fs/read_write.c:740 __do_sys_write fs/read_write.c:751 [inline] __se_sys_write fs/read_write.c:748 [inline] __x64_sys_write+0x40/0x50 fs/read_write.c:748 x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0xfffffffffffeb9c8 -> 0x0000000000098c20 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 19140 Comm: syz.4.2876 Tainted: G W syzkaller #0 PREEMPT(full) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 ================================================================== alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline] alloc_pages_noprof+0x8f/0x140 mm/mempolicy.c:2581 anon_pipe_get_page fs/pipe.c:124 [inline] anon_pipe_write+0x69c/0xb20 fs/pipe.c:515 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x5a6/0x9f0 fs/read_write.c:688 ksys_write+0xdc/0x1a0 fs/read_write.c:740 __do_sys_write fs/read_write.c:751 [inline] __se_sys_write fs/read_write.c:748 [inline] __x64_sys_write+0x40/0x50 fs/read_write.c:748 x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd38799ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd3863ef028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fd387c15fa0 RCX: 00007fd38799ce59 RDX: 000000000000fdef RSI: 00002000000004c0 RDI: 0000000000000000 RBP: 00007fd3863ef090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fd387c16038 R14: 00007fd387c15fa0 R15: 00007ffe0b5d17b8