loop4: detected capacity change from 0 to 2048
 loop4: p1 < > p4
loop4: p4 size 8388608 extends beyond EOD, truncated
==================================================================
BUG: KCSAN: data-race in __filemap_add_folio / filemap_write_and_wait_range

read-write to 0xffff8881004c75f0 of 8 bytes by task 3307 on cpu 1:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:928
 filemap_add_folio+0x98/0x1b0 mm/filemap.c:969
 page_cache_ra_unbounded+0x1f3/0x380 mm/readahead.c:275
 do_page_cache_ra mm/readahead.c:327 [inline]
 force_page_cache_ra mm/readahead.c:356 [inline]
 page_cache_sync_ra+0x256/0x6a0 mm/readahead.c:575
 filemap_get_pages+0x2d0/0x1150 mm/filemap.c:2602
 filemap_read+0x231/0xa00 mm/filemap.c:2711
 blkdev_read_iter+0x22d/0x2e0 block/fops.c:833
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x5ca/0x6f0 fs/read_write.c:572
 ksys_read+0xda/0x1a0 fs/read_write.c:715
 __do_sys_read fs/read_write.c:724 [inline]
 __se_sys_read fs/read_write.c:722 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:722
 x64_sys_call+0x2d77/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:1
 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 0xffff8881004c75f0 of 8 bytes by task 3856 on cpu 0:
 mapping_needs_writeback mm/filemap.c:641 [inline]
 filemap_write_and_wait_range+0x59/0x340 mm/filemap.c:690
 kiocb_write_and_wait+0x7a/0x110 mm/filemap.c:2801
 blkdev_read_iter+0xf9/0x2e0 block/fops.c:812
 copy_splice_read+0x3c1/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:978 [inline]
 splice_direct_to_actor+0x290/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 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+0xb39/0x2fb0 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

value changed: 0x0000000000000003 -> 0x0000000000000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3856 Comm: syz.4.172 Not tainted 6.15.0-syzkaller-11796-g5abc7438f1e9 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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