From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5EAA60A2603 for ; Thu, 29 Oct 2026 15:42:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=iTG4XzTe; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=VBWpMU/K DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=x05fCxndf1hYykwEJ06qD0sbC4EVKTE/sZRMpUPdEQc=; b=iTG4XzTeqkD1Q/JBS1ga+iwq+h p5S8sQLlWyxCRy8dExy8l3K9Dd8pYHNshs7e5DcwZRy0H3FSXWL5FJXwvOm1xMc6C7+vl++5yLkK+ bmP99EPii/NxCVaGCEXq0IMsd5C5DDNXFmJqFWo8SqT+KQ3JD7ZOLzcJjlty2UURNJrkSRs2+VIft ZNmQuJTgFG3H2teOxrxRUo2cea6+sKKtlTrvFmCUko/5b1Ru+igSeauA+AZJ2G/MFXULQfEmmPccc Ti7qnSif2N/zS+fXFSYDpstWGUZLAX5aeszfzA7yjKMOAI0q1wKvF4tHSmCmHhdji4cVDGRegA8lh SJk151Dw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMSHK-00000009elz-13vF; Thu, 29 Oct 2026 15:42:58 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMSHI-00000009elX-3TRR for kexec@lists.infradead.org; Thu, 29 Oct 2026 15:42:56 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 471E643F1A; Thu, 29 Oct 2026 15:42:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B22651F01824; Thu, 29 Oct 2026 15:42:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793288576; bh=x05fCxndf1hYykwEJ06qD0sbC4EVKTE/sZRMpUPdEQc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=VBWpMU/KLAu7f/e/8Noc5/ky4m6uYCqrAnbDe7B1Eiyf3YKYYuSJu9S6rMUBwAHRq rxdNuSkxQyc4TOUMzaXdWdtkkmG4SSedqSFbH+UiVGUvDBhSbF5ps5Rj1N4WC5Z+1M nVg6ipTCrheIKd6OSnlqmCHY40aY5JuHQMktjBDTz0bNGDllpKtBpr67h+uTjX/02/ BPVwPJ/jrEhMjy1lbZssZEiGQ47CW+eoOvd7LM9X+gXcm1M/wx1zx2VQ/uyO8q67C5 n6t0zAffCO2JyYnGumXddDp++ELqcS68IiiH0skAk3Y++ZmqpXAGKI8OP//9xNZw14 KXjSab75N39jg== Received: from phl-compute-06.internal (phl-compute-06.internal [10.202.2.46]) by mailfauth.ams.internal (Postfix) with ESMTP id 55D60198003A; Thu, 29 Oct 2026 11:42:41 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-06.internal (MEProxy); Thu, 29 Oct 2026 11:42:51 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGrojcwHOYNV1R27yGMmE+sn2SpgiwFqzTWix470caHvIOH90SafujrsKt+HTJD90 SN5SPP69uNBPn1MxWH6/eaMHHTJo/SvRT/z0Ju39Z9YfjzvKYsDYrFhgheSCBdJ9b5YIFp cIdIwys365LDAngvB6UcUIm3AGzNccSf4yN/FZLQr8sexIPFzUStpfInmWS9yXmQgvCx5c fmpZ7EbFXEWylssnvmmDQCnrMMUW1jHsUhf/jrVErtMG2Lbffr1bqxM2P6gj7ypN5ZdyZj TgAYvrVjfWikwB2MTrnw3YjFYjeMV0UDDQUTP/dXoAy/YlzoJiJh64//IR8g0ZuUVQCpel PcjjoB9Q6Jx3knI5olrCUi4hirBEGQQT+oSeGTeh25/h09KblyE6Vl7jNLQSnQit4V+35z J17GU/oPzC0n+oCMVsG/dfInPKVCtLZBd5z2d7pFm7kIyajC91WW0fXwTIMOKy3y+R1okp ekcKGTudIOrHnEZRx1GDJKalnfGvVV/PnxC4Qbu/41RL8DRLjWQuiSHsfiURJwHwuxhasY GYMOJsxXNzU8cnNcXtdtzJIfeYba/tJgBPi2qhRcbC1kxMhMglGWVDH8uH+rSsnay/vQnw D3Mh5eiVtNV6r+viH4MNCT1TzsAFldnQpQurl7rb5p9gSfzssla1/AAmhpLw X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 29 Oct 2026 11:42:39 -0400 (EDT) Date: Thu, 29 Oct 2026 15:42:38 +0000 From: Kiryl Shutsemau To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 42/46] mm/huge_memory: split huge PUDs when adjusting VMA boundaries Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-42-6f74bec9a5bb@kernel.org> <9f4128a4-85fc-4f4b-ac41-b9d348f56e37@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Oct 29, 2026 at 04:35:46PM +0100, David Hildenbrand (Arm) wrote: > On 10/29/26 15:40, David Hildenbrand (Arm) wrote: > > On 10/29/26 15:31, Kiryl Shutsemau wrote: > >> On Thu, Oct 29, 2026 at 03:24:29PM +0100, David Hildenbrand (Arm) wrote: > >>> > >>> __split_huge_pud() must split a leave. Either by zapping it (what we do right > >>> now) or by populating page tables (as in Usama's PoC). > >> > >> No, meant the situation when pud_leaf() is true, but split_pud is false, > >> so __split_huge_pud() is never hit. pud_present() is true so we proceed > >> to pmd_offset() > > > > Oh, yeah, I can add a WARN_ON_ONCE() for that, it would be a bug in the software. > > Ah, or I can just drop the split_pud check. Let me do that. Yeah, looks good. -- Kiryl Shutsemau / Kirill A. Shutemov