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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/sparse: Remove sparse buffer pre-allocation mechanism Message-ID: References: <20260410092419.2446420-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1A486140018 X-Stat-Signature: frf8u56xcj9dmucs5tdrs3t96aoirkez X-HE-Tag: 1776168691-319476 X-HE-Meta: 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 7EZSbvuO 5+6QUM3TyrQPSj0KtcIZBTqIreMILRryuZ0j+AoP1YdBz6oqdhrVrxMqAVWSz2Nco8WcRux3gG362Ja0KLi+U2LYABrL6MYm2dFEdq8c0m2zDAdHGiook5ArkfS6aTSLH7WdZQhHheeXnbINMDm1SLoEoDKaTPoyTubiQC45TeW/Zy4SCAr6lxUU1+O8Qr0CPV5eN/ITDxTnYjZFl80+o4zy62LiDC47Y8oK9oyyhvRnsf0ghk1rWT/JDDVkxIpJuKdWw01HjxFx3oz8g/VGK8Kk3Gw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 13, 2026 at 09:02:43PM +0200, David Hildenbrand (Arm) wrote: > > - > > -void * __meminit sparse_buffer_alloc(unsigned long size) > > -{ > > - void *ptr = NULL; > > - > > - if (sparsemap_buf) { > > - ptr = (void *) roundup((unsigned long)sparsemap_buf, size); > > - if (ptr + size > sparsemap_buf_end) > > - ptr = NULL; > > - else { > > - /* Free redundant aligned space */ > > - if ((unsigned long)(ptr - sparsemap_buf) > 0) > > - sparse_buffer_free((unsigned long)(ptr - sparsemap_buf)); > > - sparsemap_buf = ptr + size; > > This code implied, that we would usually get contiguous memory sections > (on the same node) to have contiguous PFNs in the SPARSE !VMEMMAP case. > That will no longer be the case (reliably). > > The code must be prepared to handle that, so I guess that is fine. And > we don't care that much about SPARSE !VMEMMAP. I've started to hunt them down ;-P https://lore.kernel.org/all/20260413104649.852228-1-rppt@kernel.org/ > Acked-by: David Hildenbrand (Arm) > > -- > Cheers, > > David -- Sincerely yours, Mike.