CPU: 1 UID: 0 PID: 25780 Comm: syz.2.6238 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 ================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff86892540 of 8 bytes by task 25778 on cpu 0: data_alloc+0x290/0x2c0 kernel/printk/printk_ringbuffer.c:1096 prb_reserve+0x86a/0xb80 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x552/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x7f/0xb0 kernel/printk/printk.c:2475 set_capacity_and_notify+0x155/0x200 block/genhd.c:93 loop_set_size+0x2e/0x70 drivers/block/loop.c:210 loop_configure+0x89c/0xa30 drivers/block/loop.c:1120 lo_ioctl+0x5fa/0x1570 drivers/block/loop.c:-1 blkdev_ioctl+0x35b/0x450 block/ioctl.c:698 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892 x64_sys_call+0x168d/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff86892540 of 8 bytes by task 25780 on cpu 1: desc_read kernel/printk/printk_ringbuffer.c:482 [inline] desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline] desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline] prb_reserve+0x239/0xb80 kernel/printk/printk_ringbuffer.c:1619 vprintk_store+0x552/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x7f/0xb0 kernel/printk/printk.c:2475 show_trace_log_lvl+0xdf/0x3d0 arch/x86/kernel/dumpstack.c:195 __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xf6/0x150 lib/dump_stack.c:120 dump_stack+0x15/0x1a lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x261/0x270 lib/fault-inject.c:174 should_failslab+0x8f/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4104 [inline] slab_alloc_node mm/slub.c:4180 [inline] kmem_cache_alloc_noprof+0x59/0x340 mm/slub.c:4207 anon_vma_alloc mm/rmap.c:94 [inline] __anon_vma_prepare+0xcf/0x310 mm/rmap.c:202 __vmf_anon_prepare mm/memory.c:3432 [inline] vmf_anon_prepare mm/internal.h:415 [inline] wp_page_copy mm/memory.c:3473 [inline] do_wp_page+0x1869/0x24e0 mm/memory.c:3939 handle_pte_fault mm/memory.c:6013 [inline] __handle_mm_fault mm/memory.c:6140 [inline] handle_mm_fault+0xc6c/0x2e80 mm/memory.c:6309 do_user_addr_fault arch/x86/mm/fault.c:1337 [inline] handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x3b9/0x6a0 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 value changed: 0x000000000004bc10 -> 0x00000000000f3160 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 25780 Comm: syz.2.6238 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 ================================================================== Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xf6/0x150 lib/dump_stack.c:120 dump_stack+0x15/0x1a lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x261/0x270 lib/fault-inject.c:174 should_failslab+0x8f/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4104 [inline] slab_alloc_node mm/slub.c:4180 [inline] kmem_cache_alloc_noprof+0x59/0x340 mm/slub.c:4207 anon_vma_alloc mm/rmap.c:94 [inline] __anon_vma_prepare+0xcf/0x310 mm/rmap.c:202 __vmf_anon_prepare mm/memory.c:3432 [inline] vmf_anon_prepare mm/internal.h:415 [inline] wp_page_copy mm/memory.c:3473 [inline] do_wp_page+0x1869/0x24e0 mm/memory.c:3939 handle_pte_fault mm/memory.c:6013 [inline] __handle_mm_fault mm/memory.c:6140 [inline] handle_mm_fault+0xc6c/0x2e80 mm/memory.c:6309 do_user_addr_fault arch/x86/mm/fault.c:1337 [inline] handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x3b9/0x6a0 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0033:0x7f4ce7c6fbe3 Code: 1f 84 00 00 00 00 00 3d 00 01 00 00 75 29 45 31 f6 48 83 c4 18 44 89 f0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 40 00 49 8b 0f <44> 88 34 01 49 83 47 10 01 eb 92 66 90 8d 90 ff fe ff ff 83 fa 1c RSP: 002b:00007f4ce640e4a0 EFLAGS: 00010202 RAX: 0000000000000400 RBX: 00007f4ce640e540 RCX: 00007f4cddfef000 RDX: 00007f4ce640e6e0 RSI: 0000000000000029 RDI: 00007f4ce640e5e0 RBP: 00000000000000f9 R08: 0000000000000008 R09: 00000000000000a7 R10: 00000000000000c0 R11: 00007f4ce640e540 R12: 0000000000000001 R13: 00007f4ce7e49b40 R14: 0000000000000020 R15: 00007f4ce640e5e0 Huh VM_FAULT_OOM leaked out to the #PF handler. Retrying PF loop2: detected capacity change from 0 to 512 EXT4-fs (loop2): encrypted files will use data=ordered instead of data journaling mode EXT4-fs (loop2): 1 truncate cleaned up EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.