syzbot

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BUG: KCSAN: data-race in block_uevent / inc_diskseq

write to 0xffff88810236a218 of 8 bytes by task 3301 on cpu 1:
 inc_diskseq+0x2d/0x40 block/genhd.c:1581
 disk_force_media_change+0x9e/0xe0 block/disk-events.c:297
 __loop_clr_fd drivers/block/loop.c:1139 [inline]
 lo_release+0x2cb/0x400 drivers/block/loop.c:1740
 bdev_release+0x373/0x3d0 block/bdev.c:-1
 blkdev_release+0x15/0x20 block/fops.c:699
 __fput+0x298/0x650 fs/file_table.c:468
 fput_close_sync+0x6e/0x120 fs/file_table.c:573
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close fs/open.c:1572 [inline]
 __x64_sys_close+0x56/0xf0 fs/open.c:1572
 x64_sys_call+0x2738/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:4
 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 0xffff88810236a218 of 8 bytes by task 2991 on cpu 0:
 block_uevent+0x31/0x50 block/genhd.c:1319
 dev_uevent+0x349/0x3d0 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+0x7f/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+0x5ca/0x6f0 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: 0x000000000000010b -> 0x000000000000010d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2991 Comm: udevd Tainted: G        W           6.16.0-syzkaller-08685-g260f6f4fda93 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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