syzbot

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BUG: KCSAN: data-race in block_uevent / inc_diskseq

write to 0xffff888102217620 of 8 bytes by task 3921 on cpu 0:
 inc_diskseq+0x2c/0x40 block/genhd.c:1517
 disk_force_media_change+0xa7/0xf0 block/disk-events.c:297
 __loop_clr_fd drivers/block/loop.c:1192 [inline]
 lo_release+0x2d2/0x400 drivers/block/loop.c:1772
 bdev_release+0x3c6/0x420 block/bdev.c:-1
 blkdev_release+0x15/0x20 block/fops.c:660
 __fput+0x2ac/0x640 fs/file_table.c:465
 fput_close_sync+0xc0/0x110 fs/file_table.c:570
 __do_sys_close fs/open.c:1581 [inline]
 __se_sys_close fs/open.c:1566 [inline]
 __x64_sys_close+0x55/0xe0 fs/open.c:1566
 x64_sys_call+0x262b/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888102217620 of 8 bytes by task 3007 on cpu 1:
 block_uevent+0x31/0x50 block/genhd.c:1256
 dev_uevent+0x304/0x390 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+0x1a8/0x280 fs/sysfs/file.c:65
 kernfs_seq_show+0x7c/0x90 fs/kernfs/file.c:205
 seq_read_iter+0x2c8/0x970 fs/seq_file.c:230
 kernfs_fop_read_iter+0xc3/0x320 fs/kernfs/file.c:279
 new_sync_read fs/read_write.c:489 [inline]
 vfs_read+0x5e6/0x710 fs/read_write.c:570
 ksys_read+0xeb/0x1b0 fs/read_write.c:713
 __do_sys_read fs/read_write.c:722 [inline]
 __se_sys_read fs/read_write.c:720 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:720
 x64_sys_call+0x2a3b/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000000d9 -> 0x00000000000000da

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3007 Comm: udevd Not tainted 6.15.0-rc1-syzkaller-00246-g900241a5cc15 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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