From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1B0931E85C; Wed, 27 May 2026 14:07:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779890838; cv=none; b=KEl7boONZmzmJLox9PiRH5IsEaagbsZOFX5gJ+vrSpcZu3yasLtJjojKpEqRHrykdoPBRIEF2Us+AdwqnIBIh0T3RaDwf3SegZCRJy6g3erqXv6djWVynnr1cnGpSF5giUQZnn9InLcRL+n66Dol/rJuErZUeqNaUH9mnM5ywJE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779890838; c=relaxed/simple; bh=fM5pzb26nz6chM1Tp0xDBtJLVszrZLmu3CnKv0EDSt8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YqvNfayVUJ13rzvRExP4s5fbXQ8E9wsNwBZnrjD6Wx/OtIw28VXxQoEQTfzoHrWGU8RanV+dKBCIjyXRRTo808jrsc7GmOF0gsDdbx29QsRjve7vQWPVND/5GjskmgJrGnvOmT+yJX2wHVFB2GtbKgYf1MdSLpP/xeIuCcWYOm4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YO3iCQgJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YO3iCQgJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DF5B1F000E9; Wed, 27 May 2026 14:07:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779890837; bh=i6CFXNwgelzox7IvTlIMcrTk9ZivAZLyNzDVQx0vmz0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=YO3iCQgJzQNEuhfJf9xffpLM/icOpMtouwv0izhfb2PKmNQmpH5td51ftB6Du9zOc fHsEanU0BPD8hO37OadHUSVoZd+RngunGa80VBbuatQFfj5tBWlCENwUPM/nfite3C C//16ZlWxP8B5dRSXTSIkQhzKGlOPwaPmn9YLyibH26prw+593LpwZ2DzvkSvUV1gH tfeSw0vUJAIXqB4Adgbf2M7zIJslaT4zS23i6ZJR/pUIHD3BJSSBiiT2dxu1lfwi1r VCpC/dAdISBdIqPPs3SA+oZCx3VP+2EOveKbCGA3Im3COWqV1EtTZXQBlp61LBnMC5 8K+VIxz8FXnmA== Message-ID: <482ee03a-c5b3-4873-a550-cc5743068616@kernel.org> Date: Wed, 27 May 2026 16:07:12 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: improve the kmem_cache_alloc_bulk API Content-Language: en-US To: Christoph Hellwig Cc: 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 References: <20260527070239.2252948-1-hch@lst.de> <20260527122148.GA6838@lst.de> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/27/26 14:21, Christoph Hellwig wrote: > On Wed, May 27, 2026 at 11:11:31AM +0200, Vlastimil Babka (SUSE) wrote: >> > value convention. Fix that and add documentation. >> > >> > Note that the few comments explaining it mention that the gfp flags >> > must allow "spinning". That's not really a term used in the memory >> > allocator, is this supposed to mean "block" or "sleep"? >> >> Page allocator now has alloc_pages_nolock() for when no spinning is >> possible, and it uses ALLOC_TRYLOCK internally. >> >> Slab has kmalloc_nolock() relying on that when it needs new pages. > > The comment long predates that, and it isn't expressed using gfp flags, Do we both mean this comment? -/* Note that interrupts must be enabled when calling this function. */ +/* + * Note that interrupts must be enabled when calling this function and gfp + * flags must allow spinning. + */ int kmem_cache_alloc_bulk_noprof(struct kmem_cache *s, gfp_t flags, size_t size, void **p) commit 46dea1744498 ("slab: refill sheaves from all nodes") from this January. Previously it was just interrupts enabled. > but by requiring separate functions so I somehow doubt that was meant. Yeah, it's expressed by the _nolock variants. But slab propagates it internally by the gfp flags, and since 46dea1744498 it affects kmem_cache_alloc_bulk(). > But I could also not see why it would not support GFP_ATOMIC / > GFP_NOWAIT allocation, so I might just be confused. Yeah those are supported because they can spin, just not sleep.