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BUG: KCSAN: data-race in __filemap_add_folio / sync_bdevs

read-write to 0xffff8881005f7178 of 8 bytes by task 2946 on cpu 0:
 __filemap_add_folio+0x66e/0x880 mm/filemap.c:919
 filemap_add_folio+0x1d3/0x350 mm/filemap.c:966
 __filemap_get_folio_mpol+0x32e/0x840 mm/filemap.c:2022
 __filemap_get_folio include/linux/pagemap.h:761 [inline]
 grow_dev_folio fs/buffer.c:960 [inline]
 grow_buffers fs/buffer.c:1026 [inline]
 __getblk_slow fs/buffer.c:1044 [inline]
 bdev_getblk+0x170/0x3c0 fs/buffer.c:1439
 __getblk include/linux/buffer_head.h:382 [inline]
 jbd2_journal_get_descriptor_buffer+0xce/0x210 fs/jbd2/journal.c:974
 jbd2_journal_commit_transaction+0xc41/0x3260 fs/jbd2/commit.c:636
 kjournald2+0x211/0x3d0 fs/jbd2/journal.c:199
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881005f7178 of 8 bytes by task 14789 on cpu 1:
 sync_bdevs+0xd3/0x260 block/bdev.c:1278
 ksys_sync fs/sync.c:105 [inline]
 __ia32_sys_sync+0x81/0xb0 fs/sync.c:111
 x64_sys_call+0x2f3a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000523 -> 0x0000000000000524

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 14789 Comm: syz.9.10116 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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