linux.git/mm/zpool.c, branch v6.15

mm: zpool: remove zpool_malloc_support_movable()

2025-03-17T07:05:41+00:00

zpool_malloc_support_movable() always returns true for zsmalloc, the only
remaining zpool driver.  Remove it and set the gfp flags in
zswap_compress() accordingly.  Opportunistically use GFP_NOWAIT instead of
__GFP_NOWARN | __GFP_KSWAPD_RECLAIM for conciseness as they are
equivalent.

Link: https://lkml.kernel.org/r/20250305061134.4105762-6-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed 
Reviewed-by: Sergey Senozhatsky 
Acked-by: Johannes Weiner 
Acked-by: Nhat Pham 
Cc: Thomas Gleixner 
Cc: Chengming Zhou 
Cc: Herbert Xu 
Cc: Minchan Kim 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton

mm: zpool: remove object mapping APIs

2025-03-17T07:05:40+00:00

zpool_map_handle(), zpool_unmap_handle(), and zpool_can_sleep_mapped() are
no longer used.  Remove them with the underlying driver callbacks.

Link: https://lkml.kernel.org/r/20250305061134.4105762-4-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed 
Reviewed-by: Sergey Senozhatsky 
Acked-by: Johannes Weiner 
Acked-by: Nhat Pham 
Cc: Chengming Zhou 
Cc: Herbert Xu 
Cc: Minchan Kim 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton

mm: zpool: add interfaces for object read/write APIs

2025-03-17T07:05:40+00:00

Patch series "Switch zswap to object read/write APIs".

This patch series updates zswap to use the new object read/write APIs
defined by zsmalloc in [1], and remove the old object mapping APIs and the
related code from zpool and zsmalloc.


This patch (of 5):

Zsmalloc introduced new APIs to read/write objects besides mapping them. 
Add the necessary zpool interfaces.

Link: https://lkml.kernel.org/r/20250305061134.4105762-1-yosry.ahmed@linux.dev
Link: https://lkml.kernel.org/r/20250305061134.4105762-2-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed 
Reviewed-by: Sergey Senozhatsky 
Acked-by: Johannes Weiner 
Acked-by: Nhat Pham 
Cc: Chengming Zhou 
Cc: Herbert Xu 
Cc: Minchan Kim 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton

mm: zbud: remove zbud

2025-03-17T05:06:01+00:00

The zbud compressed pages allocator is rarely used, most users use
zsmalloc.  zbud consumes much more memory (only stores 1 or 2 compressed
pages per physical page).  The only advantage of zbud is a marginal
performance improvement that by no means justify the memory overhead.

Historically, zsmalloc had significantly worse latency than zbud and
z3fold but offered better memory savings.  This is no longer the case as
shown by a simple recent analysis [1].  In a kernel build test on tmpfs in
a limited cgroup, zbud 2-3% less time than zsmalloc, but at the cost of
using ~32% more memory (1.5G vs 1.13G).  The tradeoff does not make sense
for zbud in any practical scenario.

The only alleged advantage of zbud is not having the dependency on
CONFIG_MMU, but CONFIG_SWAP already depends on CONFIG_MMU anyway, and zbud
is only used by zswap.

Remove zbud after z3fold's removal, leaving zsmalloc as the one and only
zpool allocator.  Leave the removal of the zpool API (and its associated
config options) to a followup cleanup after no more allocators show up.

Deprecating zbud for a few cycles before removing it was initially
proposed [2], like z3fold was marked as deprecated for 2 cycles [3]. 
However, Johannes rightfully pointed out that the 2 cycles is too short
for most downstream consumers, and z3fold was deprecated first only as a
courtesy anyway.

[1]https://lore.kernel.org/lkml/CAJD7tkbRF6od-2x_L8-A1QL3=2Ww13sCj4S3i4bNndqF+3+_Vg@mail.gmail.com/
[2]https://lore.kernel.org/lkml/Z5gdnSX5Lv-nfjQL@google.com/
[3]https://lore.kernel.org/lkml/20240904233343.933462-1-yosryahmed@google.com/

Link: https://lkml.kernel.org/r/20250129180633.3501650-3-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed 
Reviewed-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Acked-by: Nhat Pham 
Cc: Alexander Gordeev 
Cc: Chengming Zhou 
Cc: Christian Borntraeger 
Cc: Dan Streetman 
Cc: Heiko Carstens 
Cc: Huacai Chen 
Cc: Miaohe Lin 
Cc: Seth Jennings 
Cc: Sven Schnelle 
Cc: Vasily Gorbik 
Cc: Vitaly Wool 
Cc: Vlastimil Babka 
Cc: WANG Xuerui 
Signed-off-by: Andrew Morton

mm: zpool: return pool size in pages

2024-04-26T03:55:48+00:00

All zswap backends track their pool sizes in pages.  Currently they
multiply by PAGE_SIZE for zswap, only for zswap to divide again in order
to do limit math.  Report pages directly.

Link: https://lkml.kernel.org/r/20240312153901.3441-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner 
Acked-by: Yosry Ahmed 
Reviewed-by: Chengming Zhou 
Reviewed-by: Nhat Pham 
Cc: Yosry Ahmed 
Signed-off-by: Andrew Morton

mm: zswap: remove shrink from zpool interface

2023-06-19T23:19:27+00:00

Now that all three zswap backends have removed their shrink code, it is
no longer necessary for the zpool interface to include shrink/writeback
endpoints.

Link: https://lkml.kernel.org/r/20230612093815.133504-6-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo 
Reviewed-by: Yosry Ahmed 
Acked-by: Nhat Pham 
Acked-by: Johannes Weiner 
Reviewed-by: Sergey Senozhatsky 
Cc: Dan Streetman 
Cc: Minchan Kim 
Cc: Seth Jennings 
Cc: Vitaly Wool 
Signed-off-by: Andrew Morton

zpool: remove MODULE_LICENSE in non-modules

2023-04-13T20:13:54+00:00

Since commit 8b41fc4454e ("kbuild: create modules.builtin without
Makefile.modbuiltin or tristate.conf"), MODULE_LICENSE declarations
are used to identify modules. As a consequence, uses of the macro
in non-modules will cause modprobe to misidentify their containing
object file as a module when it is not (false positives), and modprobe
might succeed rather than failing with a suitable error message.

So remove it in the files in this commit, none of which can be built as
modules.

Signed-off-by: Nick Alcock 
Suggested-by: Luis Chamberlain 
Cc: Luis Chamberlain 
Cc: linux-modules@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Hitomi Hasegawa 
Cc: Dan Streetman 
Cc: Andrew Morton 
Cc: linux-mm@kvack.org
Signed-off-by: Luis Chamberlain

zpool: clean out dead code

2022-12-12T02:12:10+00:00

There is a lot of provision for flexibility that isn't actually needed or
used.  Zswap (the only zpool user) always passes zpool_ops with an .evict
method set.  The backends who reclaim only do so for zswap, so they can
also directly call zpool_ops without indirection or checks.

Finally, there is no need to check the retries parameters and bail with
-EINVAL in the reclaim function, when that's called just a few lines below
with a hard-coded 8.  There is no need to duplicate the evictable and
sleep_mapped attrs from the driver in zpool_ops.

Link: https://lkml.kernel.org/r/20221128191616.1261026-3-nphamcs@gmail.com
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Johannes Weiner 
Signed-off-by: Nhat Pham 
Cc: Dan Streetman 
Cc: Minchan Kim 
Cc: Nitin Gupta 
Cc: Seth Jennings 
Cc: Vitaly Wool 
Signed-off-by: Andrew Morton

zswap: do not allocate from atomic pool

2022-11-30T23:59:07+00:00

zswap_frontswap_load() should be called from preemptible context (we even
call mutex_lock() there) and it does not look like we need to do
GFP_ATOMIC allocaion for temp buffer.  The same applies to
zswap_writeback_entry().

Use GFP_KERNEL for temporary buffer allocation in both cases.

Link: https://lkml.kernel.org/r/Y3xCTr6ikbtcUr/y@google.com
Signed-off-by: Johannes Weiner 
Signed-off-by: Nhat Pham 
Signed-off-by: Sergey Senozhatsky 
Cc: Dan Streetman 
Cc: Minchan Kim 
Cc: Sergey Senozhatsky 
Cc: Vitaly Wool 
Signed-off-by: Andrew Morton

zpool: remove the list of pools_head

2022-01-15T14:30:31+00:00

The list of pools_head is no longer needed because the caller has been
deleted in commit 479305fd7172 ("zpool: remove zpool_evict()").

Link: https://lkml.kernel.org/r/20211215163727.GA17196@pc
Signed-off-by: Zhaoyu Liu 
Cc: Dan Streetman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds