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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764058149; bh=XqRq7kplVxhYGNzr105/v144FYOHWjKj2LupjtZhQuk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mLshyslPa3UjOa8eCf4PBZlVgAJ4YIqYI/eMgpfd4Ohv8/Y83HKae4OmSnPeYp6wo cR0lDouYxSW08C1z262NdTq01IkB+c+IEsJ+4YM4gVDy1SNmUxu4VkVHG6G67a97pn 2xc0nCP13CcSIWSCMd1u6r/CpbTIJ124t307FuwcaAg5D2VACYWiguJWtbEKgnry2m VCDUq/QVII7t/BkjlK8UNxZ7MWX/Dgqi/7mXvN6VSiL5ch64RtOu5CbQkkIdxR7lTJ dpCVyGthO8GJMt1n10pKg0PCbgQtRbLDrQCbRTyqU91egIXnBC+F3MfwSOQ873PT4W EgMtD7hWasMWg== Message-ID: <9fdc1d1f-ce00-47ff-bdf5-66e8a511be25@kernel.org> Date: Tue, 25 Nov 2025 09:09:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" To: Ilias Stamatis , akpm@linux-foundation.org, linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, nadav.amit@gmail.com, huang.ying.caritas@gmail.com, andriy.shevchenko@linux.intel.com, bhe@redhat.com, nh-open-source@amazon.com References: <20251124165349.3377826-1-ilstam@amazon.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251124165349.3377826-1-ilstam@amazon.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7A3E8C000D X-Stat-Signature: 3z8sesssbxkniyxh9et3u5yafdoffhop X-HE-Tag: 1764058150-222898 X-HE-Meta: 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 CPEiePt6 yJyTLcjgI6XMTKrWPqJcIlk4qn7SHOo2Ydil1om/oyeVG72rTXHBfWcKGCjvPdlaX18DnpdCrsZXDKGuO7rV+odotMJFX4etaFKP7gPmKdscKRdP3cy4vcG3R0FXjCs3ZnkMwd/ExeERQMvtONz8wFIVFl7zEfRLbi3eUlwWKaCtj68E7YPCzN0A7GGht3UPgtA/nZkWdbFEjZ0UeW/nhAzh0CUo26yqXQUneQQNKm15FhIRGEF4KTyjRl0oa4VD/1DdWXnh/9MnrluLrP3/uccmMeFFYLobjD62wX+jhDSiciSB3osJOsvYAWjZkZdft7fVYXuHR+bb0i8SU3STXEjiS1nzcLPiFWnZPdP7trw4oYlwWJGJD89S62qdsQ+7LZ4WWYjrOkwBaYQk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 11/24/25 17:53, Ilias Stamatis wrote: > Commit 97523a4edb7b ("kernel/resource: remove first_lvl / siblings_only > logic") removed an optimization introduced by commit 756398750e11 > ("resource: avoid unnecessary lookups in find_next_iomem_res()"). That > was not called out in the message of the first commit explicitly so it's > not entirely clear whether removing the optimization happened > inadvertently or not. Remembering the history, we have some things where the top might not fully describe what the lower levels do. An example is for example found here: Author: Dan Williams Date: Thu Feb 16 00:36:02 2023 -0800 dax/kmem: Fix leak of memory-hotplug resources While experimenting with CXL region removal the following corruption of /proc/iomem appeared. Before: f010000000-f04fffffff : CXL Window 0 f010000000-f02fffffff : region4 f010000000-f02fffffff : dax4.0 f010000000-f02fffffff : System RAM (kmem) The CXL Windows will certainly not match System RAM, as one example. How would your change affect such cases? -- Cheers David