syzbot

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BUG: KCSAN: data-race in block_uevent / inc_diskseq

write to 0xffff8881020ed218 of 8 bytes by task 629 on cpu 0:
 inc_diskseq+0x2d/0x40 block/genhd.c:1583
 disk_force_media_change+0x9e/0xe0 block/disk-events.c:297
 __loop_clr_fd drivers/block/loop.c:1152 [inline]
 lo_release+0x2eb/0x420 drivers/block/loop.c:1752
 bdev_release+0x373/0x3d0 block/bdev.c:-1
 blkdev_release+0x15/0x20 block/fops.c:706
 __fput+0x29b/0x650 fs/file_table.c:468
 fput_close_sync+0xad/0x190 fs/file_table.c:573
 __do_sys_close fs/open.c:1573 [inline]
 __se_sys_close fs/open.c:1558 [inline]
 __x64_sys_close+0x55/0xf0 fs/open.c:1558
 x64_sys_call+0x2c25/0x3000 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881020ed218 of 8 bytes by task 3001 on cpu 1:
 block_uevent+0x31/0x50 block/genhd.c:1320
 dev_uevent+0x375/0x400 drivers/base/core.c:2700
 kobject_uevent_env+0x379/0x570 lib/kobject_uevent.c:573
 kobject_synth_uevent+0x6c0/0x7f0 lib/kobject_uevent.c:207
 uevent_store+0x26/0x70 drivers/base/core.c:2773
 dev_attr_store+0x4a/0x70 drivers/base/core.c:2437
 sysfs_kf_write+0xfe/0x120 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x1eb/0x300 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5a6/0x9f0 fs/read_write.c:686
 ksys_write+0xdc/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2847/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000073d -> 0x000000000000073e

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3001 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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