Re: [PATCH v3 1/5] hugetlb: use page.private for hugetlb specific page flags

[Oscar Salvador <osalvador@suse.de>]

On Fri, Jan 22, 2021 at 11:52:27AM -0800, Mike Kravetz wrote:
> As hugetlbfs evolved, state information about hugetlb pages was added.
> One 'convenient' way of doing this was to use available fields in tail
> pages.  Over time, it has become difficult to know the meaning or contents
> of fields simply by looking at a small bit of code.  Sometimes, the
> naming is just confusing.  For example: The PagePrivate flag indicates
> a huge page reservation was consumed and needs to be restored if an error
> is encountered and the page is freed before it is instantiated.  The
> page.private field contains the pointer to a subpool if the page is
> associated with one.
> 
> In an effort to make the code more readable, use page.private to contain
> hugetlb specific page flags.  These flags will have test, set and clear
> functions similar to those used for 'normal' page flags.  More importantly,
> an enum of flag values will be created with names that actually reflect
> their purpose.
> 
> In this patch,
> - Create infrastructure for hugetlb specific page flag functions
> - Move subpool pointer to page[1].private to make way for flags
>   Create routines with meaningful names to modify subpool field
> - Use new HPageRestoreReserve flag instead of PagePrivate
> 
> Conversion of other state information will happen in subsequent patches.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE L3