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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43ead33d65asm11893147f8f.4.2026.04.16.01.45.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2026 01:45:09 -0700 (PDT) Date: Thu, 16 Apr 2026 04:45:06 -0400 From: "Michael S. Tsirkin" To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Johannes Weiner , Zi Yan Subject: Re: [PATCH RFC 3/9] mm: add __GFP_PREZEROED flag and folio_test_clear_prezeroed() Message-ID: <20260416022758-mutt-send-email-mst@kernel.org> References: <20260413163644-mutt-send-email-mst@kernel.org> <20260414062524-mutt-send-email-mst@kernel.org> <6fc307da-72b4-4d07-9e34-5e6c0563124c@kernel.org> MIME-Version: 1.0 In-Reply-To: <6fc307da-72b4-4d07-9e34-5e6c0563124c@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: x-Ra2mUGh9jq2F9y2350MA7_pTnklkq3dKqHZJebYts_1776329111 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8A0B6C000B X-Stat-Signature: rzcrimb133ys4dcjhrxu4sabuc561h5z X-Rspam-User: X-HE-Tag: 1776329114-660795 X-HE-Meta: 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 JVRf6APi Yp12FoHjY6pbphkAhXpWZw8NcWn3AeJIabMgPLEmtMwVjEI7zTCxYD9D1cF3SY5lnTDVIrm/SvXn+o41drvSLmxcsWO6C7k8pDhy3ccNldqopmeLxPkKQFZ4zjI9GMZ98bCXxzmTxJel+GceTpEEXGErc+ILzfjWQu3FBuq7Sy19kq0Zb+4xeqlUm7416TIk5xifK/Tj+4lNpJBv8FMJIAkudVT2jF8B78UPnUx3rG716D8kST08WC/TPnTfLmntP5YMa4vAlsxx7qZyqwt5FJfbbROU2/Gw+/ESqz74B58ekaKFyyHXq2ngnzjkyWdalsZ1ICiee6JhzwFhUpv5YUGv6l2LIPgH3ZhsyQEQMz4NOM1H38EdD9u7BmN8FDCHdrd82 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 14, 2026 at 05:46:58PM +0200, David Hildenbrand (Arm) wrote: > On 4/14/26 12:29, Michael S. Tsirkin wrote: > > On Tue, Apr 14, 2026 at 11:04:04AM +0200, David Hildenbrand (Arm) wrote: > >> On 4/13/26 22:37, Michael S. Tsirkin wrote: > >>> > >>> I admit I only vaguely understand the core mm refactoring you are suggesting. > >>> > >> > >> Oh, I was hoping claude would figure that out for you. > > > > We figured it out together) > > :) > > [...] > > > > > > > Pretty much what I did, except I felt it is better to change the > > existing APIs. A bit more churn, but in return there's less of a chance > > we forget to pass the user address. > > > > Because, if we do, the result works fine on x86 but corrupts memory > > on other arches. > > Converting everything is probably cleaner long term, But there are many > instances where we just don't really have an address, or the address is > irrelevant, because we wouldn't care about the difference when zeroing. > > vma_alloc_folio() is the API to use when we have a VMA + address. > > But yeah, something that is harder to mess up would be nice. Well ... I am making progress on this but it is very intrusive. Are we sure we do not want simply this, just maybe renaming the flags? For example: __GFP_PREZERO -> __GFP_ZERO_HINT - request a hint that the allocated page is zero And an API hiding the fact that the hint is in page->private. Hmm? > -- > Cheers, > > David