syzbot

loop7: detected capacity change from 0 to 16384
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BUG: KCSAN: data-race in __filemap_add_folio / filemap_write_and_wait_range

read-write to 0xffff888100489838 of 8 bytes by task 3304 on cpu 0:
 __filemap_add_folio+0x671/0x8b0 mm/filemap.c:919
 filemap_add_folio+0x1d3/0x350 mm/filemap.c:966
 page_cache_ra_unbounded+0x20e/0x450 mm/readahead.c:282
 do_page_cache_ra mm/readahead.c:334 [inline]
 force_page_cache_ra+0x18d/0x1d0 mm/readahead.c:364
 page_cache_sync_ra+0x110/0x560 mm/readahead.c:582
 filemap_get_pages+0x30a/0x1280 mm/filemap.c:2690
 filemap_read+0x231/0xa10 mm/filemap.c:2800
 blkdev_read_iter+0x22d/0x2e0 block/fops.c:855
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x6c0/0x7f0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:717
 __do_sys_read fs/read_write.c:726 [inline]
 __se_sys_read fs/read_write.c:724 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:724
 x64_sys_call+0x2886/0x3020 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100489838 of 8 bytes by task 15410 on cpu 1:
 mapping_needs_writeback mm/filemap.c:634 [inline]
 filemap_write_and_wait_range+0x59/0x370 mm/filemap.c:683
 filemap_write_and_wait include/linux/pagemap.h:65 [inline]
 sync_blockdev+0x35/0x50 block/bdev.c:276
 loop_set_status+0x122/0x6a0 drivers/block/loop.c:1245
 loop_set_status_old drivers/block/loop.c:1362 [inline]
 lo_ioctl+0x799/0x13a0 drivers/block/loop.c:1551
 blkdev_ioctl+0x387/0x460 block/ioctl.c:804
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000001 -> 0x0000000000000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15410 Comm: syz.2.3023 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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