syzbot

==================================================================
BUG: KCSAN: data-race in bdev_disk_changed / bdev_set_nr_sectors

write to 0xffff8881005f0648 of 8 bytes by task 31453 on cpu 0:
 bdev_set_nr_sectors+0x50/0x70 block/bdev.c:428
 set_capacity block/genhd.c:61 [inline]
 set_capacity_and_notify+0x6e/0x170 block/genhd.c:74
 loop_set_size+0x2e/0x70 drivers/block/loop.c:235
 loop_configure+0xaf9/0xca0 drivers/block/loop.c:1096
 lo_ioctl+0x682/0x12e0
 blkdev_ioctl+0x375/0x460 block/ioctl.c:634
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881005f0648 of 8 bytes by task 31425 on cpu 1:
 bdev_nr_sectors include/linux/blkdev.h:744 [inline]
 get_capacity include/linux/blkdev.h:754 [inline]
 bdev_disk_changed+0x2a0/0xbe0 block/partitions/core.c:696
 blkdev_get_whole+0x227/0x240 block/bdev.c:661
 bdev_open_by_dev+0x28a/0x5e0 block/bdev.c:871
 blkdev_open+0xfb/0x200 block/fops.c:615
 do_dentry_open+0x637/0xbd0 fs/open.c:953
 vfs_open+0x4a/0x50 fs/open.c:1087
 do_open fs/namei.c:3641 [inline]
 path_openat+0x1821/0x1d40 fs/namei.c:3798
 do_filp_open+0xf6/0x200 fs/namei.c:3825
 do_sys_openat2+0xab/0x110 fs/open.c:1404
 do_sys_open fs/open.c:1419 [inline]
 __do_sys_openat fs/open.c:1435 [inline]
 __se_sys_openat fs/open.c:1430 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1430
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000000 -> 0x00000000000000a4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31425 Comm: udevd Not tainted 6.8.0-rc5-syzkaller-00329-gab0a97cffa0b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
blk_print_req_error: 8 callbacks suppressed
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0