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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lbPC9u+W; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4DE49606A329; Wed, 4 Nov 2026 16:07:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lbPC9u+W Received: by smtp.kernel.org (Postfix) with ESMTPSA id D060B1F00919; Wed, 4 Nov 2026 16:07:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; 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-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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 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