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Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vfvSi-0000000Gh72-07Qu; Wed, 14 Jan 2026 07:38:40 +0000 Date: Wed, 14 Jan 2026 07:38:40 +0000 From: Al Viro To: Harry Yoo Cc: linux-mm@kvack.org, Vlastimil Babka , linux-fsdevel@vger.kernel.org, Linus Torvalds , Christian Brauner , Jan Kara , Mateusz Guzik , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 01/15] static kmem_cache instances for core caches Message-ID: <20260114073840.GT3634291@ZenIV> References: <20260110040217.1927971-1-viro@zeniv.linux.org.uk> <20260110040217.1927971-2-viro@zeniv.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 601E6160006 X-Stat-Signature: ormtx4pujckzfzkxgica37uc5pfgapcz X-HE-Tag: 1768376235-985406 X-HE-Meta: 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 ipypW5JZ 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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: On Wed, Jan 14, 2026 at 04:30:24PM +0900, Harry Yoo wrote: > SLAB_NO_MERGE prevents both side of merging - when 1) creating the cache, > and when 2) another cache tries to create an alias from it. > > Avoiding 1) makes sense, but is there a reason to prevent 2)? > > If it's fine for other caches to merge into a cache with static > duration, then it's sufficient to update find_mergeable() to not attempt > creating an alias during cache creation if args->preallocated is > specified (instead of using SLAB_NO_MERGE). Umm... For static-in-module - definitely (what if it goes away before the dynamic alias?), for globally static... might be fine, I guess...