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BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c27550 of 8 bytes by task 32502 on cpu 0:
 bh_lru_install fs/buffer.c:1345 [inline]
 find_get_block_common+0x498/0x8e0 fs/buffer.c:1410
 bdev_getblk+0x4d/0x3f0 include/linux/gfp.h:-1
 sb_getblk_gfp include/linux/buffer_head.h:392 [inline]
 __read_extent_tree_block+0xad/0x470 fs/ext4/extents.c:564
 ext4_find_extent+0x4ca/0x7a0 fs/ext4/extents.c:939
 ext4_ext_map_blocks+0x11f/0x38a0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:613 [inline]
 ext4_map_blocks+0x626/0xd20 fs/ext4/inode.c:816
 _ext4_get_block+0x10a/0x350 fs/ext4/inode.c:916
 ext4_get_block_unwritten+0x2a/0xb0 fs/ext4/inode.c:949
 ext4_block_write_begin+0x650/0xcf0 fs/ext4/inode.c:1203
 ext4_write_begin+0x636/0xe90 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x1f0/0x6b0 fs/ext4/inode.c:3130
 generic_perform_write+0x184/0x490 mm/filemap.c:4314
 ext4_buffered_write_iter+0x1ee/0x3c0 fs/ext4/file.c:299
 ext4_file_write_iter+0x387/0xf60 fs/ext4/file.c:-1
 iter_file_splice_write+0x66b/0xa20 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x312/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c27550 of 8 bytes by task 27179 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1551
 cpu_needs_drain mm/swap.c:787 [inline]
 __lru_add_drain_all+0x287/0x450 mm/swap.c:877
 lru_add_drain_all+0x10/0x20 mm/swap.c:893
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1348
 generic_shutdown_super+0xe6/0x210 fs/super.c:643
 kill_block_super+0x2a/0x70 fs/super.c:1722
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7444
 deactivate_locked_super+0x75/0x1c0 fs/super.c:474
 deactivate_super+0x97/0xa0 fs/super.c:507
 cleanup_mnt+0x2a9/0x320 fs/namespace.c:1318
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1325
 task_work_run+0x131/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88811b3c9820

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27179 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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