Implementing alignment guarantees for kmalloc()

kmalloc() is a frequently used primitive for the allocation of small objects in the kernel. During the 2019 Linux Storage, Filesystem, and Memory Management Summit, Vlastimil Babka led a session about the unexpected alignment problems developers face when using this function. After a few months he has come back with the second version of a patch set implementing a natural alignment guarantee for kmalloc(). From the strong opposition it faced initially, it seemed that the change would not get accepted. However, it ended up in Linus Torvalds's tree. Let's explore what happened.

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