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b=H65gbf2iEGv2XZKo4se061BH3bpHpe3VUjVrcnH1e+nvvMAQO8XAvhKSS1QlzRZj/ Xuf1p9OvYpjwTNrVOHuRn76V/YYYj7Ma7qMir7f49NfjE/PsXgWBuBnPntta+oizSu IJQtP0EFsaHz8PDDj3NYWZ4e09Ec2QXBZbsnRvDSm3knw6q/ZaB4s6547BwB2e/p+Y BsqkzdIscaS0Sef0dyM67Pv66p53nbpBoqUhBVJk23R8kRQjAfWRoEqS8jrHGFt0Dt ya3hvDQVXDeh3pkiuW6MyJqSxzt0hN6M3/lEuWBIE1avqqnJAW9wOLw7FET6ICk+jb 3laaHp7g0kQNA== Date: Mon, 29 Jun 2026 14:48:28 +0300 From: Mike Rapoport To: Wei Yang Cc: linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Taku Izumi , Yuan Liu , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] mm/mm_init: drop overlap_memmap_init() Message-ID: References: <20260625073941.145014-1-rppt@kernel.org> <20260625073941.145014-3-rppt@kernel.org> <20260625095846.4e2tl3fbduc24erg@master> <20260626092952.qoihjgphv43ezw6v@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260626092952.qoihjgphv43ezw6v@master> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 647C3A000A X-Stat-Signature: p6j7zfi7tpa5fb7ei5asqju4qebj8nnf X-HE-Tag: 1782733715-367120 X-HE-Meta: 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 alYONbaM ALswyI58J8/CZHoEe9DkVivuH+DgU7WAUjQdzFhbuR6bAG4sZCUpaOQCJyig+nrMGXiW2/WyvbDrY1F6UDr5VyhOp7RbsLfu5e1m/Jsbxn5UgYGy5qo7yFt0Wo/zIoDxbm3kUu7iWZYNE0ZQUP6xTbe+v04rUTbbZC1KSql5szd5R5ivzg4nnsXebMzvXzJ2FhVIQF0QkMnXRFqxp8V8h4iLPZhQuXpjyNb02h48h5KiFhwTS7ikdakiN7/jwdT1O+rKSDIwc1UKdMYsrhfv8nMANEbeOYa6kqqLB0boXlzPV0qCGHxJEBveu3r4pq+OaDiFJKR0EuiJoqLzfsC4Qn6X7dqS5uoHQydW0Ylpyd/OOCXDxYgIe9p2IJpx4J0DwZffKaPkCk1XIT9Z3EeZ/wxbJhg0HJAEU1EZeg9Cc9HyA1WQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 26, 2026 at 09:29:52AM +0000, Wei Yang wrote: > On Fri, Jun 26, 2026 at 10:40:32AM +0300, Mike Rapoport wrote: > >Hi Wei, > > > >On Thu, Jun 25, 2026 at 09:58:47AM +0000, Wei Yang wrote: > >> On Thu, Jun 25, 2026 at 10:39:40AM +0300, Mike Rapoport wrote: > >> >From: "Mike Rapoport (Microsoft)" > >> > > >> >When ZONE_NORMAL and ZONE_MOVABLE could overlap because kernelcore=mirror > >> >didn't reduce the span of ZONE_NORMAL, initialization of the memory map had > >> >to skip overlapping pages during initialization of ZONE_MOVABLE to avoid > >> >double initialization of the same struct pages. > >> > > >> >Since kernelcore=mirror works now the same way as other variants of > >> >kernelcore=/movablecore=, and adjusts the span of ZONE_NORMAL, there can't > >> >be an overlap between ZONE_NORMAL and ZONE_MOVABLE. > >> > > >> >Remove overlap_memmap_init(). > >> > > >> > >> Do you think this is valuable to mention the double init for the overlapped > >> range? > > > >Not sure I follow. > >We had this weird overlap_memmap_init() exactly to avoid double init. > > > > Yes, this is really weird. > > As I described the detail in [1], before this change kernel would have > overlapped zone range like: > > Normal [100000, 1c0000] > Movable [140000, 1c0000] > > Which means [140000, 1c0000] belongs to both Normal and Movable. > And memmap_init_range() would be called on this range twice for Normal and > Movable respectively. And we want overlap_memmap_init() could skip init this > to Normal. Because actually, the memory in this range belongs to Movable Zone. > > But overlap_memmap_init() only would skip for Zone Movable. This means when > init to Zone Normal, it doesn't skip as we want. And when init to Zone > Movable, we don't expect it to skip. I'll add something along these lines into the cover letter and will merge it as a merge commit. Will send v2 soon. > [1]: https://lore.kernel.org/linux-mm/20260623092351.13031-3-richard.weiyang@gmail.com/ > > -- > Wei Yang > Help you, Help me -- Sincerely yours, Mike.