syzbot

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BUG: KCSAN: data-race in filemap_read / filemap_read

write to 0xffff88813bd15390 of 8 bytes by task 3498 on cpu 0:
 filemap_read+0x605/0x680 mm/filemap.c:2662
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2772
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:2014 [inline]
 copy_splice_read+0x26b/0x4b0 fs/splice.c:364
 vfs_splice_read fs/splice.c:992 [inline]
 splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1069
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3c4/0x980 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff88813bd15390 of 8 bytes by task 3493 on cpu 1:
 filemap_read+0x605/0x680 mm/filemap.c:2662
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2772
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:2014 [inline]
 copy_splice_read+0x26b/0x4b0 fs/splice.c:364
 vfs_splice_read fs/splice.c:992 [inline]
 splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1069
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3c4/0x980 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000190000 -> 0x00000000001a0000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3493 Comm: syz-executor.2 Not tainted 6.7.0-rc2-syzkaller-00014-gc2d5304e6c64 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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EXT4-fs error (device loop2): ext4_validate_block_bitmap:441: comm syz-executor.2: bg 0: block 234: padding at end of block bitmap is not set
EXT4-fs (loop2): Delayed block allocation failed for inode 18 at logical offset 0 with max blocks 1441 with error 28
EXT4-fs (loop2): This should not happen!! Data will be lost

EXT4-fs (loop2): Total free blocks count 0
EXT4-fs (loop2): Free/Dirty block details
EXT4-fs (loop2): free_blocks=0
EXT4-fs (loop2): dirty_blocks=1504
EXT4-fs (loop2): Block reservation details
EXT4-fs (loop2): i_reserved_data_blocks=94