syzbot

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BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c26fd0 of 8 bytes by task 3501 on cpu 0:
 bh_lru_install fs/buffer.c:1345 [inline]
 find_get_block_common+0x4f0/0x960 fs/buffer.c:1410
 __find_get_block_nonatomic fs/buffer.c:1429 [inline]
 bdev_getblk+0x83/0x3b0 fs/buffer.c:1453
 __bread_gfp+0x51/0x250 fs/buffer.c:1515
 sb_bread include/linux/buffer_head.h:346 [inline]
 fat12_ent_bread+0xd0/0x380 fs/fat/fatent.c:77
 fat_ent_read+0x3b3/0x5c0 fs/fat/fatent.c:368
 fat_get_cluster+0x4b2/0x7b0 fs/fat/cache.c:266
 fat_bmap_cluster fs/fat/cache.c:299 [inline]
 fat_get_mapped_cluster+0xe4/0x240 fs/fat/cache.c:320
 fat_bmap+0x254/0x280 fs/fat/cache.c:384
 __fat_get_block fs/fat/inode.c:128 [inline]
 fat_get_block+0xd3/0x5e0 fs/fat/inode.c:189
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0xcec/0x1d80 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3509 [inline]
 fat_direct_IO+0x102/0x1d0 fs/fat/inode.c:283
 generic_file_read_iter+0x21b/0x330 mm/filemap.c:2917
 copy_splice_read+0x442/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:981 [inline]
 splice_direct_to_actor+0x290/0x680 fs/splice.c:1086
 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+0x2bb4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c26fd0 of 8 bytes by task 3502 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1551
 smp_call_function_many_cond+0x2a9/0xc60 kernel/smp.c:821
 on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1043
 on_each_cpu_cond include/linux/smp.h:105 [inline]
 invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1560
 kill_bdev block/bdev.c:90 [inline]
 set_blocksize+0x24f/0x310 block/bdev.c:207
 sb_set_blocksize+0x7a/0x100 block/bdev.c:224
 fat_fill_super+0xa09/0x1ce0 fs/fat/inode.c:1631
 vfat_fill_super+0x24/0x30 fs/fat/namei_vfat.c:1197
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 vfat_get_tree+0x1c/0x30 fs/fat/namei_vfat.c:1202
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1208 [inline]
 do_new_mount_fc fs/namespace.c:3651 [inline]
 do_new_mount+0x24d/0x660 fs/namespace.c:3727
 path_mount+0x4a5/0xb70 fs/namespace.c:4037
 do_mount fs/namespace.c:4050 [inline]
 __do_sys_mount fs/namespace.c:4238 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4215
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4215
 x64_sys_call+0x2b51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881057b8d68

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3502 Comm: syz.4.5 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================
FAT-fs (loop4): Directory bread(block 32) failed
FAT-fs (loop4): Directory bread(block 33) failed
FAT-fs (loop4): Directory bread(block 34) failed
FAT-fs (loop4): Directory bread(block 35) failed
FAT-fs (loop4): Directory bread(block 36) failed
FAT-fs (loop4): Directory bread(block 37) failed
FAT-fs (loop4): Directory bread(block 38) failed
FAT-fs (loop4): Directory bread(block 39) failed
FAT-fs (loop4): Directory bread(block 40) failed
FAT-fs (loop4): Directory bread(block 41) failed