259043e3b7
If CONFIG_ZSWAP is set to N, it means zswap cannot be enabled.
zswap_never_enabled() should return true.
The only effect of this issue is that with Barry's latest large folio
swapin patches for zram ("mm: support mTHP swap-in for zRAM-like
swapfile"), we will always fallback to order-0 swapin, even mistakenly
when !CONFIG_ZSWAP.
Basically this bug makes Barry's in progress patches not work at all.
The API was created to inform the mm core that zswap has never been
enabled, allowing the mm core to perform mTHP swap-in. This is a
transitional solution until zswap supports mTHP. If zswap has been
enabled, performing mTHP swap-in will result in corrupted data. You
may find the answer in the mTHP swap-in series:
https://lore.kernel.org/linux-mm/CAJD7tkZ4FQr6HZpduOdvmqgg_-whuZYE-Bz5O2t6yzw6Yg+v1A@mail.gmail.com/
Link: https://lkml.kernel.org/r/20240629232231.42394-1-21cnbao@gmail.com
Fixes: 0300e17d67c3 ("mm: zswap: add zswap_never_enabled()")
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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.