syzbot

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BUG: KCSAN: data-race in block_uevent / inc_diskseq

write to 0xffff8881022f9218 of 8 bytes by task 6856 on cpu 0:
 inc_diskseq+0x2d/0x40 block/genhd.c:1583
 disk_force_media_change+0x9e/0xe0 block/disk-events.c:297
 loop_configure+0x6e6/0xa50 drivers/block/loop.c:1043
 lo_ioctl+0x1e1/0x1350 drivers/block/loop.c:1523
 blkdev_ioctl+0x34f/0x440 block/ioctl.c:705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:584
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
 x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881022f9218 of 8 bytes by task 5559 on cpu 1:
 block_uevent+0x31/0x50 block/genhd.c:1320
 dev_uevent+0x372/0x400 drivers/base/core.c:2700
 uevent_show+0x117/0x200 drivers/base/core.c:2756
 dev_attr_show+0x3c/0xa0 drivers/base/core.c:2421
 sysfs_kf_seq_show+0x1a0/0x280 fs/sysfs/file.c:65
 kernfs_seq_show+0x82/0xa0 fs/kernfs/file.c:205
 seq_read_iter+0x316/0x940 fs/seq_file.c:230
 kernfs_fop_read_iter+0xc4/0x300 fs/kernfs/file.c:279
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x649/0x770 fs/read_write.c:572
 ksys_read+0xda/0x1a0 fs/read_write.c:715
 __do_sys_read fs/read_write.c:724 [inline]
 __se_sys_read fs/read_write.c:722 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:722
 x64_sys_call+0x27bc/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000001f0 -> 0x00000000000001fc

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5559 Comm: udevd Not tainted 6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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