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Rao" , linux-mm@kvack.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC PATCH] mm: z3fold: rename CONFIG_Z3FOLD to CONFIG_Z3FOLD_DEPRECATED Message-ID: References: <20240112193103.3798287-1-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20240112193103.3798287-1-yosryahmed@google.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B584D40003 X-Stat-Signature: 1ow4myqboh6xr97uppezjra3onnstg37 X-Rspam-User: X-HE-Tag: 1705423498-338904 X-HE-Meta: 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 sNU0LzW9 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Yosry Ahmed writes: >The z3fold compressed pages allocator is not widely used, most users use >zsmalloc. The only disadvantage of zsmalloc in comparison is the >dependency on MMU, and zbud is a more common option for !MMU as it was >the default zswap allocator for a long time. > >In hopes of having a single compressed pages allocator at some point, >and following in the footsteps of SLAB, deprecate z3fold. Rename the >user-visible option so that users with CONFIG_Z3FOLD=y get a new prompt >with explanation during make oldconfig. Remove CONFIG_Z3FOLD=y from >defconfigs. > >Existing users, if any, should voice their objections. Otherwise, we can >remove z3fold in a few releases. > >Signed-off-by: Yosry Ahmed Acked-by: Chris Down Thanks. We are definitely hurting users as well by keeping this around with its known issues when writeback is disabled, for example. >--- >I have limited understanding of Kconfigs. I modelled this after commit >eb07c4f39c3e ("mm/slab: rename CONFIG_SLAB to CONFIG_SLAB_DEPRECATED"), >but one difference is that CONFIG_Z3FOLD is a tristate. I made >CONFIG_Z3FOLD_DEPRECATED a boolean config, and CONFIG_Z3FOLD default y >so that it is on by default if CONFIG_Z3FOLD_DEPRECATED is selected. I >am not sure if that's the correct way to do this. > >--- > arch/loongarch/configs/loongson3_defconfig | 1 - > arch/powerpc/configs/ppc64_defconfig | 1 - > mm/Kconfig | 13 +++++++++++-- > 3 files changed, 11 insertions(+), 4 deletions(-) > >diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig >index 33795e4a5bd63..89b66b6c6a1d5 100644 >--- a/arch/loongarch/configs/loongson3_defconfig >+++ b/arch/loongarch/configs/loongson3_defconfig >@@ -85,7 +85,6 @@ CONFIG_ZPOOL=y > CONFIG_ZSWAP=y > CONFIG_ZSWAP_COMPRESSOR_DEFAULT_ZSTD=y > CONFIG_ZBUD=y >-CONFIG_Z3FOLD=y > CONFIG_ZSMALLOC=m > # CONFIG_COMPAT_BRK is not set > CONFIG_MEMORY_HOTPLUG=y >diff --git a/arch/powerpc/configs/ppc64_defconfig b/arch/powerpc/configs/ppc64_defconfig >index 544a65fda77bc..d39284489aa26 100644 >--- a/arch/powerpc/configs/ppc64_defconfig >+++ b/arch/powerpc/configs/ppc64_defconfig >@@ -81,7 +81,6 @@ CONFIG_MODULE_SIG_SHA512=y > CONFIG_PARTITION_ADVANCED=y > CONFIG_BINFMT_MISC=m > CONFIG_ZSWAP=y >-CONFIG_Z3FOLD=y > CONFIG_ZSMALLOC=y > # CONFIG_SLAB_MERGE_DEFAULT is not set > CONFIG_SLAB_FREELIST_RANDOM=y >diff --git a/mm/Kconfig b/mm/Kconfig >index 1902cfe4cc4f5..bc6cc97c08349 100644 >--- a/mm/Kconfig >+++ b/mm/Kconfig >@@ -193,15 +193,24 @@ config ZBUD > deterministic reclaim properties that make it preferable to a higher > density approach when reclaim will be used. > >-config Z3FOLD >- tristate "3:1 compression allocator (z3fold)" >+config Z3FOLD_DEPRECATED >+ bool "3:1 compression allocator (z3fold) (DEPRECATED)" > depends on ZSWAP > help >+ Deprecated and scheduled for removal in a few cycles. If you have >+ a good reason for using Z3FOLD rather than ZSMALLOC or ZBUD, please >+ contact linux-mm@kvack.org and the zswap maintainers. >+ > A special purpose allocator for storing compressed pages. > It is designed to store up to three compressed pages per physical > page. It is a ZBUD derivative so the simplicity and determinism are > still there. > >+config Z3FOLD >+ tristate >+ default y >+ depends on Z3FOLD_DEPRECATED >+ > config ZSMALLOC > tristate > prompt "N:1 compression allocator (zsmalloc)" if ZSWAP >-- >2.43.0.275.g3460e3d667-goog > >