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imf02.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=lst.de; spf=pass (imf02.hostedemail.com: domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779884417; a=rsa-sha256; cv=none; b=LaneF/m8am5kP8pKMrxC6Ckk+QVhgqNKEs1ovb+lK8SZN7WhFw6Ik99umq8VBDy4IwyGMj AaJqD2L4RX/fUutL813NgKff1odzWiKw24lhj1+EHj84cBgMGRtK+uj5mkKslAyCL/39LY 7ILWh5S2U6vu6Hxjoh01PmMDicz/ZHE= Received: by verein.lst.de (Postfix, from userid 2407) id F307A68B05; Wed, 27 May 2026 14:20:13 +0200 (CEST) Date: Wed, 27 May 2026 14:20:13 +0200 From: Christoph Hellwig To: "Vlastimil Babka (SUSE)" Cc: Christoph Hellwig , Harry Yoo , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Jesper Dangaard Brouer , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, io-uring@vger.kernel.org, kasan-dev@googlegroups.com, bpf@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH] mm/slab: improve kmem_cache_alloc_bulk Message-ID: <20260527122013.GA6765@lst.de> References: <20260527070239.2252948-1-hch@lst.de> <20260527070239.2252948-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7888080010 X-Stat-Signature: escja3w711tnhd4f5d9kykcnyum7srix X-Rspam-User: X-HE-Tag: 1779884417-913546 X-HE-Meta: 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 yK50anx3 rD0y8UsgKNvencAaCPyiWzexA3HDH58lQZU1UhGZKMigr5e/b26X3toKQ8dOlH2HxCrDH+fhW/Yvkq4havJvEFodVBZbmuJ+F6z/6ym25Syd6w6wOZ3seNhHNVwNPXqM75C7mKiQOHgDPsjORWhfadTdCv6UTqJE9uhENlxDZHR4zV+w= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, May 27, 2026 at 11:38:21AM +0200, Vlastimil Babka (SUSE) wrote: > On 5/27/26 09:02, Christoph Hellwig wrote: > > The kmem_cache_alloc_bulk return value is weird. It returns the number > > of allocated objects, but that must always be 0 or the requested number > > based on the implementations and the handling in the callers, but that > > assumption is not actually documented anywhere, which confuses automated > > review tools. > > > > Fix this by returning a bool if the allocation succeeded and adding a > > kerneldoc comment explaining the API. > > > > Signed-off-by: Christoph Hellwig > > Would 0 / -ENOMEM be more like what people would expect? I guess both that > and bool are better than the current API. I find an errno return where the API could not return anything but the specific error code a bit odd. But even that would be a lot better than the current version.