linux-kernel - [PATCH 0/3] mm: zswap: trivial folio conversions

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Date: Fri, 24 May 2024 03:38:15 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>, Nhat Pham <nphamcs@...il.com>, 
	Chengming Zhou <chengming.zhou@...ux.dev>, Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Yosry Ahmed <yosryahmed@...gle.com>
Subject: [PATCH 0/3] mm: zswap: trivial folio conversions

Some trivial folio conversions in zswap code.

The mean reason I included a cover letter is that I wanted to get
feedback on what other trivial conversions can/should be done in
mm/zswap.c (keeping in mind that only order-0 folios are supported
anyway).  These are the things I came across while searching for 'page'
in mm/zswap.c, and chose not to do anything about for now:

1. zswap_max_pages(), zswap_accept_thr_pages(), zswap_total_pages():
  - We can use 'size' instead of 'pages' and shift the return by
    PAGE_SHIFT. This adds an unnecessary shift, but I doubt it matters
    at all. The motivation is to get rid of 'page' to find things that
    should be converted more easily.

2. Counters names: zswap_stored_pages, zswap_written_back_pages, etc.

3. Comments all over the place reference 'page' instead of 'folio'.

4. shrink_memcg_cb(), zswap_shrinker_scan():
  - Rename encountered_page_in_swap_cache to
    encounterd_folio_in_swap_cache, or even better: folio_eexist or
    hit_swap_cache.

5. entry_to_nid():
  - It's tempting to try to use folio_to_nid(virt_to_folio()), but I
    think this adds an unnecessary call to compound_head(). It may not
    matter in practice though because the page is always a head page.

Yosry Ahmed (3):
  mm: zswap: use sg_set_folio() in zswap_{compress/decompress}()
  mm :zswap: use kmap_local_folio() in zswap_load()
  mm: zswap: make same_filled functions folio-friendly

 mm/zswap.c | 41 ++++++++++++++++++-----------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

-- 
2.45.1.288.g0e0cd299f1-goog