syzbot

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BUG: KCSAN: data-race in block_uevent / inc_diskseq

write to 0xffff888101079220 of 8 bytes by task 4043 on cpu 0:
 inc_diskseq+0x2c/0x40 block/genhd.c:1514
 disk_force_media_change+0x9f/0xf0 block/disk-events.c:297
 __loop_clr_fd drivers/block/loop.c:1178 [inline]
 lo_release+0x2c7/0x400 drivers/block/loop.c:1758
 bdev_release+0x3c6/0x420
 blkdev_release+0x15/0x20 block/fops.c:660
 __fput+0x2ac/0x640 fs/file_table.c:464
 __fput_sync+0x96/0xc0 fs/file_table.c:550
 __do_sys_close fs/open.c:1580 [inline]
 __se_sys_close fs/open.c:1565 [inline]
 __x64_sys_close+0x55/0xe0 fs/open.c:1565
 x64_sys_call+0x266c/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888101079220 of 8 bytes by task 3000 on cpu 1:
 block_uevent+0x31/0x50 block/genhd.c:1253
 dev_uevent+0x2f3/0x380 drivers/base/core.c:2674
 uevent_show+0x11e/0x210 drivers/base/core.c:2732
 dev_attr_show+0x3a/0xa0 drivers/base/core.c:2424
 sysfs_kf_seq_show+0x17c/0x250 fs/sysfs/file.c:59
 kernfs_seq_show+0x7c/0x90 fs/kernfs/file.c:205
 seq_read_iter+0x2d1/0x930 fs/seq_file.c:230
 kernfs_fop_read_iter+0xc0/0x310 fs/kernfs/file.c:279
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0x5cc/0x6f0 fs/read_write.c:565
 ksys_read+0xe8/0x1b0 fs/read_write.c:708
 __do_sys_read fs/read_write.c:717 [inline]
 __se_sys_read fs/read_write.c:715 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:715
 x64_sys_call+0x2874/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000047 -> 0x0000000000000048

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3000 Comm: udevd Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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