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BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c277a0 of 8 bytes by task 3311 on cpu 0:
 bh_lru_install fs/buffer.c:1235 [inline]
 find_get_block_common+0x459/0x870 fs/buffer.c:1300
 bdev_getblk+0x4d/0x3f0 include/linux/gfp.h:-1
 __getblk include/linux/buffer_head.h:380 [inline]
 sb_getblk include/linux/buffer_head.h:386 [inline]
 __ext4_get_inode_loc+0x303/0x930 fs/ext4/inode.c:4890
 ext4_get_inode_loc fs/ext4/inode.c:5018 [inline]
 ext4_reserve_inode_write+0xd7/0x250 fs/ext4/inode.c:6372
 __ext4_mark_inode_dirty+0x8c/0x3d0 fs/ext4/inode.c:6550
 ext4_dirty_inode+0x92/0xc0 fs/ext4/inode.c:6587
 __mark_inode_dirty+0x16f/0x710 fs/fs-writeback.c:2621
 generic_update_time fs/inode.c:2192 [inline]
 file_update_time_flags+0x29b/0x2e0 fs/inode.c:2422
 file_update_time+0x17/0x20 fs/inode.c:2443
 ext4_page_mkwrite+0x164/0xad0 fs/ext4/inode.c:6753
 do_page_mkwrite mm/memory.c:3668 [inline]
 wp_page_shared mm/memory.c:4069 [inline]
 do_wp_page+0xc65/0x2040 mm/memory.c:4288
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault mm/memory.c:6549 [inline]
 handle_mm_fault+0x8b9/0x2e70 mm/memory.c:6718
 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

read to 0xffff888237c277a0 of 8 bytes by task 21606 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1441
 smp_call_function_many_cond+0x2a7/0xb70 kernel/smp.c:836
 on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1057
 on_each_cpu_cond include/linux/smp.h:106 [inline]
 invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1450
 kill_bdev block/bdev.c:90 [inline]
 blkdev_flush_mapping+0x94/0x1a0 block/bdev.c:720
 blkdev_put_whole block/bdev.c:727 [inline]
 bdev_release+0x2bf/0x3d0 block/bdev.c:1152
 blkdev_release+0x15/0x20 block/fops.c:705
 __fput+0x29b/0x630 fs/file_table.c:510
 ____fput+0x1c/0x30 fs/file_table.c:538
 task_work_run+0x130/0x1a0 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:67 [inline]
 exit_to_user_mode_loop+0x1f4/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x232/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811bb44c98 -> 0xffff8881075c98f0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 21606 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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