syzbot

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BUG: KCSAN: data-race in bdev_set_nr_sectors / blkdev_read_iter

write to 0xffff888100405048 of 8 bytes by task 12697 on cpu 0:
 bdev_set_nr_sectors+0x50/0x70 block/bdev.c:438
 set_capacity block/genhd.c:60 [inline]
 set_capacity_and_notify+0x6e/0x170 block/genhd.c:73
 loop_set_size+0x2e/0x70 drivers/block/loop.c:237
 loop_configure+0xaf6/0xca0 drivers/block/loop.c:1100
 lo_ioctl+0x682/0x12e0
 blkdev_ioctl+0x38e/0x480 block/ioctl.c:615
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888100405048 of 8 bytes by task 3430 on cpu 1:
 bdev_nr_sectors include/linux/blkdev.h:772 [inline]
 bdev_nr_bytes include/linux/blkdev.h:777 [inline]
 blkdev_read_iter+0x44/0x370 block/fops.c:560
 call_read_iter include/linux/fs.h:1862 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x3b7/0x580 fs/read_write.c:470
 ksys_read+0xeb/0x1a0 fs/read_write.c:613
 __do_sys_read fs/read_write.c:623 [inline]
 __se_sys_read fs/read_write.c:621 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:621
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0x00000000000000a4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3430 Comm: udevd Not tainted 6.4.0-rc7-syzkaller-00014-g692b7dc87ca6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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