syzbot

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BUG: KCSAN: data-race in blkdev_ioctl / set_capacity_and_notify

write to 0xffff888100405420 of 8 bytes by task 6060 on cpu 0:
 i_size_write include/linux/fs.h:871 [inline]
 set_capacity block/genhd.c:41 [inline]
 set_capacity_and_notify+0xaa/0x1c0 block/genhd.c:55
 loop_set_size drivers/block/loop.c:298 [inline]
 loop_configure+0xc8e/0xeb0 drivers/block/loop.c:1295
 lo_ioctl+0x59b/0x1340 drivers/block/loop.c:1847
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1604
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888100405420 of 8 bytes by task 6025 on cpu 1:
 i_size_read include/linux/fs.h:849 [inline]
 blkdev_ioctl+0x147/0x3c0 block/ioctl.c:570
 block_ioctl+0x6d/0x80 fs/block_dev.c:1604
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000000 -> 0x000000000001c000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6025 Comm: systemd-udevd Not tainted 5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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