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b=FbgV3wVsZqo9w2ruVmy8VP2xJrKH6PVVF1CJzV0hBpuSGPDuVaZTvJqv+3/KgVK1E GwIFHt80Cl8diJF4uGxipeEOrdoCYI01B26PI3JZzll56seXCbv1Rmogw2MAxtmTL9 sf53K+UkCoJGXPSUs5G8CqLU87xbFewtkQcsC+zCFi2349cpdk2WAja/4gvQ2K9lW8 cTkvwAM5VlV3QGG6zKNHGWJIZ0EQvEzeJa2wJZsqG1J7boGyWoCtWr+C0xQddg74FN pLj88z6UjrCUNEUJOmwAlORhFochQSTEon3QbIPEcvjypUMRxoqTLfV2bdLM8KoLTh ENe5yePI5pbYQ== Date: Sun, 8 Nov 2026 17:00:11 +0000 From: Harry Yoo To: "Vlastimil Babka (SUSE)" Cc: Andrey Ryabinin , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Geert Uytterhoeven , Conor Dooley , Damien Le Moal , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com Subject: Re: [PATCH v3 05/10] mm, slab: rework KMALLOC_RECLAIM handling of SLUB_TINY Message-ID: References: <20261105-slub_tiny_rework-v3-0-0484ce59eabb@kernel.org> <20261105-slub_tiny_rework-v3-5-0484ce59eabb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261105-slub_tiny_rework-v3-5-0484ce59eabb@kernel.org> X-Rspamd-Queue-Id: 0B0D314000D X-Rspamd-Server: rspam12 X-Stat-Signature: 9dndnnnsbrmpieim6jxm4hxhrunnzn33 X-Rspam-User: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794157213-809943 X-HE-Meta: U2FsdGVkX18yrKNu7qqmgorw0AsbcG5jsWkEw0d3T3UGygcHDbgmmYiE/G0ax4KQiNqL0CdBIk04SXNnejPZJnisbID++K1IyN7QHysgwhsftl6n5bjnHgS/zYNDr51HigyzdQrFu0ZE9+ssLU5WLfqe9rmgQFFx/Mi72BXCXcmMTaLHXdgACszfL7XjDrOBcwM+m1r9utfLQDAIam3qLZaGjGMcC8oI5mgRgLfe5ZrO0wkvZVCyMiMDygAVkAG/BCS/C9DB0HzDO252Yn1tZ0Cwr0eJN3jffP7Q3RRtjmeu2NoWna1n4+LQOjXgrolzKUItgoKpOFnNlNA9QRdr7WAbLcGd219F5w/aJaqhjZOlWBjjl+yddjLeJzWT+vq/155QktgNB4gIj15DwtBdoXR8NL8XdhMAnQpBtTxS/7VPSKNZuaBlX3D/FYXvBHfTYMA4OO5FN6v3WKTNv5bTfTWvWzu1ggWgFFNJorC71KtIKzXreSIfGdA+jneWMQs6cYnEoi4bhJxfENOiF0ri5g23LUTKqedqQsa+vwux56EdMvUnwBDMSmiyu6ykxoLiUhXvVPPQzIpsOQA93ZnKTtW0WCZiKUUpm0VZlKSFRizGFo9k8MuKLGWPHWBU8cS/twDbN/c4opzYAavhyqQuVPp5RLPMxvXv2qpT3yxSUc9SmIsKdQ5im+uZwChD/YAA9Br92ezX9+Z54EbnWy/auQRaEVe6bcnrOXSAMwMuC44dqk0/PUje+aMrzZglGRD+kAgNjevVNcxH2HdhX0sTlUfgfNVDgPa6yRGvj8Imkxx6lAI2ViJ5OEgiCRdJrpLwn97XJ+DsJLIAfseItxbg9z5ydkeFCNnueTpZhQJXBbh5xVmqAc3ZKyWfU0SuN/4U7CrNXgcgjpEJrxNNQH3/JZq3EslcGb5UXKpYmy4SdT4n4eXWLnkxN6nqG+cuat/ofkDz0Wpq539gMeAeijq aORE360M 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 05, 2026 at 09:43:54AM +0100, Vlastimil Babka (SUSE) wrote: > One (relatively minor) aspect of CONFIG_SLUB_TINY is the assumption that > letting reclaimable and non-reclaimable caches merge will save more > memory, which is more important on small systems than the page allocator > level fragmentation (where distinguishing reclaimable slabs should > help). > > For now that has been achieved by #ifdefs that result in making the > SLAB_RECLAIM_ACCOUNT no-op and aliasing KMALLOC_RECLAIM to > KMALLOC_NORMAL on the enum values level. > > With the goal of converting CONFIG_SLUB_TINY to a boot-time decision, > rework this so that SLAB_RECLAIM_ACCOUNT and KMALLOC_RECLAIM are > distinctly defined always. Nice! > Now, creation of kmalloc-rcl caches is > avoided by assigning a pointer to the normal kmalloc cache on the > kmalloc_caches array level. > > To prepare disconnecting of this boot-time decision (and the evaluation > of the need for kmalloc_no_objext) from CONFIG_SLUB_TINY, introduce a > slub_tiny_enabled variable that's initialized to the CONFIG_SLUB_TINY > state. > > There is one minor functional change for CONFIG_SLUB_TINY=y. Since > SLAB_RECLAIM_ACCOUNT is not 0 anymore, caches that differ only in that > flag will stop being mergeable. If that turns out to have a noticeable > impact on memory footprint, we can adjust the merging decisions to > ignore SLAB_RECLAIM_ACCOUNT when slub_tiny_enabled is true. > > Signed-off-by: Vlastimil Babka (SUSE) > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) -- Cheers, Harry / Hyeonggon