Re: [LSF/MM/BPF TOPIC] Reclaiming & documenting page flags

[Mike Rapoport <rppt@kernel.org>]

On Mon, Jan 29, 2024 at 04:32:03AM +0000, Matthew Wilcox wrote:
> Our documentation of the current page flags is ... not great.  I think
> I can improve it for the page cache side of things; I understand the
> meanings of locked, writeback, uptodate, dirty, head, waiters, slab,
> mlocked, mappedtodisk, error, hwpoison, readahead, anon_exclusive,
> has_hwpoisoned, hugetlb and large_remappable.
> 
> Where I'm a lot more shaky is the meaning of the more "real MM" flags,
> like active, referenced, lru, workingset, reserved, reclaim, swapbacked,
> unevictable, young, idle, swapcache, isolated, and reported.
> 
> Perhaps we could have an MM session where we try to explain slowly and
> carefully to each other what all these flags actually mean, talk about
> what combinations of them make sense, how we might eliminate some of
> them to make more space in the flags word, and what all this looks like
> in a memdesc world.
> 
> And maybe we can get some documentation written about it!  Not trying
> to nerd snipe Jon into attending this session, but if he did ...

I suspect Jon will be there anyway, but not sure he'd be willing to do the
writing :)

I was going to propose the "mm docs" session again, but this one seems more
useful than talking yet again about how hard it is to get MM documentation
done.

And I can take on myself putting the explanations from this session into
writing.
 
> [thanks to Amir for reminding me that I meant to propose this topic]
> 

-- 
Sincerely yours,
Mike.