loop2: detected capacity change from 0 to 2048
==================================================================
BUG: KCSAN: data-race in read_pages / read_pages

read-write to 0xffff88815b0fda80 of 4 bytes by task 14202 on cpu 0:
 read_pages+0x23c/0x530 mm/readahead.c:170
 page_cache_ra_unbounded+0x2aa/0x2e0 mm/readahead.c:269
 do_page_cache_ra mm/readahead.c:299 [inline]
 page_cache_ra_order mm/readahead.c:546 [inline]
 ondemand_readahead+0x524/0x690 mm/readahead.c:668
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:717
 filemap_readahead mm/filemap.c:2472 [inline]
 filemap_get_pages+0x397/0xf90 mm/filemap.c:2513
 filemap_read+0x214/0x680 mm/filemap.c:2593
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2781
 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:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read-write to 0xffff88815b0fda80 of 4 bytes by task 14199 on cpu 1:
 read_pages+0x23c/0x530 mm/readahead.c:170
 page_cache_ra_unbounded+0x2aa/0x2e0 mm/readahead.c:269
 do_page_cache_ra mm/readahead.c:299 [inline]
 page_cache_ra_order mm/readahead.c:546 [inline]
 ondemand_readahead+0x524/0x690 mm/readahead.c:668
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:717
 filemap_readahead mm/filemap.c:2472 [inline]
 filemap_get_pages+0x397/0xf90 mm/filemap.c:2513
 filemap_read+0x214/0x680 mm/filemap.c:2593
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2781
 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:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000004 -> 0xfffffffb

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14199 Comm: syz-executor.2 Not tainted 6.7.0-rc7-syzkaller-00049-g453f5db0619e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================
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 16472 with max blocks 2 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=16480