CVE-2021-46921: In the Linux kernel, the following vulnerability has been resolved: locking/qrwlock: Fix ordering in queued_write_lock_

A vulnerability in the Linux kernel's queued read-write lock mechanism allowed a race condition where a reader could modify a value while a writer thought it had acquired the lock. The problem occurred because the writer's lock acquisition wasn't properly ordered with respect to the atomic compare-and-exchange operation (cmpxchg, a CPU instruction that compares and swaps values atomically), creating a window where reads could see stale data before the write lock was truly secured.