<TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xda/0x130 lib/dump_stack.c:106
 dump_stack+0x15/0x20 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x21f/0x230 lib/fault-inject.c:153
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff86f43498 of 8 bytes by task 18365 on cpu 0:
 data_alloc+0x216/0x2c0 kernel/printk/printk_ringbuffer.c:1074
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 __ext4_msg+0x18a/0x1a0 fs/ext4/super.c:937
 __ext4_fill_super fs/ext4/super.c:5630 [inline]
 ext4_fill_super+0x3009/0x38b0 fs/ext4/super.c:5696
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1318
 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5728
 vfs_get_tree+0x51/0x190 fs/super.c:1519
 do_new_mount+0x203/0x660 fs/namespace.c:3335
 path_mount+0x496/0xb30 fs/namespace.c:3662
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86f43498 of 8 bytes by task 18381 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x37e/0x400 arch/x86/kernel/dumpstack.c:285
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xda/0x130 lib/dump_stack.c:106
 dump_stack+0x15/0x20 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x21f/0x230 lib/fault-inject.c:153
 __should_fail_alloc_page+0xfd/0x110 mm/fail_page_alloc.c:42
 prepare_alloc_pages mm/page_alloc.c:4250 [inline]
 __alloc_pages+0x108/0x340 mm/page_alloc.c:4466
 vma_alloc_folio+0x6a3/0x8c0 mm/mempolicy.c:2240
 shmem_alloc_folio mm/shmem.c:1579 [inline]
 shmem_alloc_and_acct_folio mm/shmem.c:1603 [inline]
 shmem_get_folio_gfp+0x801/0x1200 mm/shmem.c:1948
 shmem_get_folio mm/shmem.c:2079 [inline]
 shmem_write_begin+0xa6/0x1d0 mm/shmem.c:2573
 generic_perform_write+0x1cf/0x410 mm/filemap.c:3923
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4018
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4044
 call_write_iter include/linux/fs.h:1871 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000100003bcf -> 0x0000000100004be1

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18381 Comm: syz-executor.1 Not tainted 6.4.0-syzkaller-11311-g24be4d0b46bb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
==================================================================
 __should_fail_alloc_page+0xfd/0x110 mm/fail_page_alloc.c:42
 prepare_alloc_pages mm/page_alloc.c:4250 [inline]
 __alloc_pages+0x108/0x340 mm/page_alloc.c:4466
 vma_alloc_folio+0x6a3/0x8c0 mm/mempolicy.c:2240
 shmem_alloc_folio mm/shmem.c:1579 [inline]
 shmem_alloc_and_acct_folio mm/shmem.c:1603 [inline]
 shmem_get_folio_gfp+0x801/0x1200 mm/shmem.c:1948
 shmem_get_folio mm/shmem.c:2079 [inline]
 shmem_write_begin+0xa6/0x1d0 mm/shmem.c:2573
 generic_perform_write+0x1cf/0x410 mm/filemap.c:3923
 __generic_file_write_iter+0xa1/0x120 mm/filemap.c:4018
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4044
 call_write_iter include/linux/fs.h:1871 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f077ad32fff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 99 fd ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 cc fd ff ff 48
RSP: 002b:00007f077a0f3f10 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f077ad32fff
RDX: 0000000000040000 RSI: 00007f0771cd4000 RDI: 0000000000000004
RBP: 00007f0771cd4000 R08: 0000000000000000 R09: 00000000000004c0
R10: 0000000000040000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f077a0f3fdc R14: 00007f077a0f3fe0 R15: 0000000020000ec2
 </TASK>
syz-executor.1 (18381) used greatest stack depth: 10048 bytes left