/syz5:
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86cf5d70 of 88 bytes by task 22464 on cpu 1:
 prb_reserve+0x6e6/0xae0 kernel/printk/printk_ringbuffer.c:1690
 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
 fserror_report+0x427/0x500 fs/fserror.c:182
 fserror_report_metadata include/linux/fserror.h:67 [inline]
 __ext4_error+0x152/0x310 fs/ext4/super.c:828
 ext4_acquire_dquot+0x1bb/0x200 fs/ext4/super.c:7024
 dqget+0x527/0x8c0 fs/quota/dquot.c:980
 __dquot_initialize+0x20c/0x7c0 fs/quota/dquot.c:1508
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1570
 ext4_process_orphan+0x32/0x1c0 fs/ext4/orphan.c:327
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5693 [inline]
 ext4_fill_super+0x3414/0x37c0 fs/ext4/super.c:5816
 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:5848
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3839
 path_mount+0x4d0/0xbc0 fs/namespace.c:4159
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 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/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86cf5d70 of 8 bytes by task 22446 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x383/0x950 kernel/printk/printk_ringbuffer.c:2171
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2242
 __console_flush_and_unlock kernel/printk/printk.c:3392 [inline]
 console_unlock+0x146/0x280 kernel/printk/printk.c:3413
 vprintk_emit+0x3e4/0x600 kernel/printk/printk.c:2479
 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
 mem_cgroup_print_oom_meminfo+0x117/0x260 mm/memcontrol.c:1614
 dump_header+0xa2/0x240 mm/oom_kill.c:469
 oom_kill_process+0x295/0x350 mm/oom_kill.c:1047
 out_of_memory+0x97d/0xb80 mm/oom_kill.c:1185
 mem_cgroup_out_of_memory mm/memcontrol.c:1695 [inline]
 mem_cgroup_oom mm/memcontrol.c:1718 [inline]
 try_charge_memcg+0x62e/0xa10 mm/memcontrol.c:2456
 try_charge mm/memcontrol.c:2556 [inline]
 charge_memcg mm/memcontrol.c:4744 [inline]
 mem_cgroup_swapin_charge_folio+0x103/0x1f0 mm/memcontrol.c:4830
 __swap_cache_prepare_and_add+0x67/0x460 mm/swap_state.c:498
 swap_cache_alloc_folio+0xa2/0x120 mm/swap_state.c:574
 swap_cluster_readahead+0x26e/0x3d0 mm/swap_state.c:748
 swapin_readahead+0xde/0x840 mm/swap_state.c:923
 do_swap_page+0x2fe/0x21e0 mm/memory.c:4802
 handle_pte_fault mm/memory.c:6320 [inline]
 __handle_mm_fault mm/memory.c:6455 [inline]
 handle_mm_fault+0xb46/0x3020 mm/memory.c:6624
 do_user_addr_fault+0x62f/0x1050 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0x0000000000003106 -> 0x0000000000005106

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22446 Comm: syz.5.16385 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
cache 4096
rss 0
shmem 0
mapped_file 0
dirty 0
writeback 0
workingset_refault_anon 229
workingset_refault_file 192
swap 212992
swapcached 7684096
pgpgin 456466
pgpgout 456463
pgfault 470660
pgmajfault 119
inactive_anon 0
active_anon 0
inactive_file 0
active_file 12288
unevictable 0
hierarchical_memory_limit 314572800
hierarchical_memsw_limit 9223372036854771712
total_cache 4096
total_rss 0
total_shmem 0
total_mapped_file 0
total_dirty 0
total_writeback 0
total_workingset_refault_anon 229
total_workingset_refault_file 192
total_swap 212992
total_swapcached 7684096
total_pgpgin 456466
total_pgpgout 456463
total_pgfault 470660
total_pgmajfault 119
total_inactive_anon 0
total_active_anon 0
total_inactive_file 0
total_active_file 12288
total_unevictable 0
oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=syz5,mems_allowed=0,oom_memcg=/syz5,task_memcg=/syz5,task=syz.5.16385,pid=22446,uid=0
Memory cgroup out of memory: Killed process 22446 (syz.5.16385) total-vm:159704kB, anon-rss:1224kB, file-rss:22432kB, shmem-rss:0kB, UID:0 pgtables:132kB oom_score_adj:1000