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t=1793808468; bh=flMXNxiWEHoQiHXSBFrkZmNU7RGBVxxqF50tkqZe2B4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=lbPC9u+WqYTYnkkFYDRtOoONdVem35rdhn1WaS6YkI8WISarsntkV4jhI5q2fjK9+ zspoBxzyTUkVHUYhcWT+UZhrrzs06Ytq2pzC5iTmI2HNz1qFMVfT/9i4abcyJ65Tki oEmwxGDSQC4cp9XWKAjS2WiCXIuTzH2lGkKajODaW77el/K7fQrd9jIp8mR2vqwPXV w18nv7QajlOZt3UEKAZm5dlTzI5S6awAYFSiiZEX9loTMWocH5GahmjM3U+Wfo4DEP YmlN9NpzVlydvVlh91CES/Dgm0Jom6aqg6OBuQ+IL2qClJ3+H5VDMcS4mmLRNU9zyZ 6gxO/iPPf1cvA== Message-ID: <92e52f59-e096-4cb1-bce8-8081f489002c@kernel.org> Date: Wed, 4 Nov 2026 17:07:34 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/hugetlb: allow crashkernel to reuse hugetlb CMA memory To: Kiryl Shutsemau , Usama Arif Cc: Andrew Morton , baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, muchun.song@linux.dev, osalvador@suse.de, jbohac@suse.cz, sourabhjain@linux.ibm.com, ruanjinjie@huawei.com, leitao@debian.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com References: <20261104142727.2894800-1-usama.arif@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 57874C0008 X-Stat-Signature: 3is3tofnzkjfpgb6b1iosk1fc5f48ceb X-Rspam-User: X-HE-Tag: 1793808469-752334 X-HE-Meta: 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 5Iyms2zj alzyp2VZ/Cw5DxSgccE+WY1to12k3iPLoedveNBgyMGoCo5f9E0JWFG2hhLDp00jHKwmDpjZJAaNx/FlAICvHH8rThuxiwTq3L2ZxD8XWoDlNyhcbDI5gjR5TUnJHafkccWTVjZwg83RosN4gqpzQoGGUPQqbHPv0YocRyxsnmZ0ARhruQ1fT9o3TH9enYyR2sC2/ytnd0F9D4+3mmWMaqEZ+Snzkt5tG/MduIqSfo4pUwaVrrKi0JlAwrV02/EUGFv6p 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 11/4/26 16:20, Kiryl Shutsemau wrote: > On Wed, Nov 04, 2026 at 06:27:27AM -0800, Usama Arif wrote: >> Use a separate suffix to make the exclusion of existing HugeTLB >> allocations from the vmcore an explicit choice. > > The crashkernel=size,cma documentation already says that pages allocated > from the range are not in the vmcore and that it should not be used if > dumping of userspace memory is intended. HugeTLB pages are userspace > memory. I don't see what a new suffix makes explicit that ",cma" does > not already. > > Why not let crashkernel=size,cma take hugetlb CMA first and reserve a > dedicated area only for what hugetlb CMA does not cover? With > hugetlb_cma=6G crashkernel=2G,cma there would be no extra CMA at all. Hiding that complexity from the user would indeed be nice. -- Cheers, David