Usama Arif 9ba85f5529 mm: do not start/end writeback for pages stored in zswap
Most of the work done in folio_start_writeback is reversed in
folio_end_writeback.  For e.g.  NR_WRITEBACK and NR_ZONE_WRITE_PENDING are
incremented in start_writeback and decremented in end_writeback.  Calling
end_writeback immediately after start_writeback (separated by
folio_unlock) cancels the affect of most of the work done in start hence
can be removed.

There is some extra work done in folio_end_writeback, however it is
incorrect/not applicable to zswap:
- folio_end_writeback incorrectly increments NR_WRITTEN counter,
  eventhough the pages aren't written to disk, hence this change
  corrects this behaviour.
- folio_end_writeback calls folio_rotate_reclaimable, but that only
  makes sense for async writeback pages, while for zswap pages are
  synchronously reclaimed.

Link: https://lkml.kernel.org/r/20240612100109.1616626-1-usamaarif642@gmail.com
Link: https://lkml.kernel.org/r/20240610143037.812955-1-usamaarif642@gmail.com
Signed-off-by: Usama Arif <usamaarif642@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-03 19:30:07 -07:00
2024-06-30 14:32:24 -07:00
2024-06-29 13:48:24 -07:00
2024-06-17 18:35:12 -07:00
2024-06-26 22:02:55 +02:00
2024-06-21 08:03:55 -04:00
2024-06-14 17:57:10 -07:00
2022-09-28 09:02:20 +02:00
2022-10-10 12:00:45 -07:00
2024-06-28 09:18:01 -07:00
2024-06-30 14:40:44 -07:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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