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b=QsjnKBIveTMF7UYQJeJoj497i829x0ccFzZw4zOgFOiqRBg6lnNi6YuIYuCoQrJf5 oQ7wa6yF63oSUGq2PYrM9Fv1rsp0g/EDZlOrW9ApS+j2DlOQsfOSipK4XaDhlnLePF dEV5JIqYjb2thSuFnM1aSxTYdzqxerudU2HhxThvavNxaglycBpeiWWBZ9yV0vYLAd tSeqmeXjnlENqPk5D4BKc306FogQneS3lTFMgxpErif8+sk+sU7dfNiJn/1wwdh1Un U/NwJMakKBbdpc42QpxEknf7Xc8XW5wK2GW5NEepWE/0UReU4nT+6dSMc+hNeq9QpE 9dW/3OCIJnYCQ== Message-ID: <4621037e-d051-4db1-bb58-ffe8c0afa3de@kernel.org> Date: Fri, 19 Jun 2026 15:45:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: page_ext: validate section in for_each_page_ext iterator To: Matthew Wilcox Cc: Luiz Capitulino , Ketan , Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , kernel@oss.qualcomm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260617-page_ext-v1-1-37ad802b1a38@oss.qualcomm.com> <1dbebf73-6c46-44e1-ac6a-f5ffa9849b37@kernel.org> <698e5cdc-8f1d-4984-bb54-a4b7979b4dc8@redhat.com> <3149fcee-eded-49b0-baf4-ab69c27ff063@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 15E791C000D X-Stat-Signature: 5fte7r3pj5onqhzi63teaz54f59ruach X-HE-Tag: 1781876736-455254 X-HE-Meta: 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 cN1cT6Ov LCELZwO1XF0wCeHT6D6nPzmU8AUeThfB1PwPQYq0aT7BCWNr0bqTyU1gqfEX266mZejFpYyl8BmSHYDWE+lZNEiGEid8pkFgMzkWKLIzjthHfJNCBmSSFyZHrXA8M+aYEZ6OdsmSpjywHwiqzMZD6ahcuqBr+vnnxGxQBCQymml0UWcNdgMKHE+FSgNNTQPjMtMq0m7+cpMFL3skQP6NgkisOonyWtDFOp936Yb/rLFvaP7N65DP8NpSWXDfBX4yGmOVUa5nNAZyUA4iJho+7ntIOc5oUYyseO4xSRQir25VTvmHpJIx5YhUWEw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/19/26 15:38, Matthew Wilcox wrote: > On Fri, Jun 19, 2026 at 10:00:59AM +0200, David Hildenbrand (Arm) wrote: >> Likely we should just handle that in the iterator, looking up page-ext for something >> that doesn't exist is weird. > > Yes, but I prefer to pass 'max' to the _next step explicitly, rather > than put it in the iterator struct. Untested patch attached. Yeah, no strong opinion, same fix idea. > > The other way to do it is s/index/remaining/ and count it down rather > than upwards. But that assumes none of the iterator users look at > iter->index, and I don't have the patience to check that. > > I find it weird that somebody botheresd to add kernel-doc for > page_ext_iter_begin/next. They're internal implementation and really > shouldn't have public documentation. Yeah, Luiz was just very thorough :) -- Cheers, David