From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B1DE32AAC6 for ; Fri, 24 Apr 2026 07:26:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777015585; cv=none; b=PfKj606j/2GWoIud/JyFpPbWHwoFm7rZFDgoOUfvtas42vpA0qPWhdfwqW9jIlE+U8QjYJb8+3Ktc/8nsjPwIp92Ox6NWRCpYPqPtSy9LJviBMS6e0Z8Aov4mVF7fB6q5mEUafmhUNCy3DmMDXwRHTCgbnvh28otu6iz6/nV+BI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777015585; c=relaxed/simple; bh=5dmzXPh5bpR2t1b0uCMuOAqmdZYp5LGnT+Lwxr5M/oo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jS492L/v5UE4cZcsfOGksUPnp/9J5CEZOGnVRT6djCsSMH5mhVovVCltTA79UQrsMlzcVtuwxSkZ5Uhg+9wpC9PbKkTnwbVSh1nBsfeiQs5vXdTN1UXITKXD6OWJ4Lfwr+ZsN2/AMQDbaqJeXmzHDfbmDkovPQad/CFld9ffE6U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=C6/S2Vgh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="C6/S2Vgh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B53E4C19425; Fri, 24 Apr 2026 07:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777015584; bh=5dmzXPh5bpR2t1b0uCMuOAqmdZYp5LGnT+Lwxr5M/oo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=C6/S2VghcGegNnoRZvvUqEJC5Se8UaQriA/q3zpdTKceryHugwPWmW3hLepdvu1F+ 2pM+7AAqUoTcF2vFap5zsQEkhXzDgXYV78p0OUuJuBbqwBv3O/8qmPDmftAAl3npF0 xW/rsHX18FkQjJ+YAAeoc6OliYWOCGHcOEkrOczwwIR7JJOdORUKzS+ONFq0/aasrm hP3Sx+oWS6eTZF945+EHKpbaheEyeT0B2vNJIJS1KrWjWeYm3RWxWjG9f4dFefYjb2 Mwbeyt6hyV1NXzUvZvL3q+lySBi28hFUyuJMztEzXOwji88N0hU/rAZhQILqhxViia bamHzpaHrw1WA== Message-ID: Date: Fri, 24 Apr 2026 09:26:18 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/5] mm: Introduce zone_appears_fragmented() To: =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Matthew Brost Cc: intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner References: <20260423055656.1696379-1-matthew.brost@intel.com> <20260423055656.1696379-2-matthew.brost@intel.com> <76191a17-18bf-4e9b-9ab5-dc9a48abfabb@kernel.org> <291406b26b8badf2e565996515931d9ebe50208f.camel@linux.intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <291406b26b8badf2e565996515931d9ebe50208f.camel@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 4/24/26 09:05, Thomas Hellström wrote: > On Thu, 2026-04-23 at 15:21 -0700, Matthew Brost wrote: >> On Thu, Apr 23, 2026 at 12:08:36PM -0700, Matthew Brost wrote: >>> >>> If the order were included in shrink_control, there is about a 95% >>> certain that this change would allow TTM / Xe to break the >>> problematic >>> kswapd feedback loop. This may also better express the intent of >>> the >>> problem we are trying to fix here. >>> >>> For reference, the cover letter [1] details the problem. >>> >>> Any guidance from the core MM folks would be appreciated—would >>> adding >>> the order to shrink_control be an acceptable solution? >>> >>> Matt >>> >>> [1] https://patchwork.freedesktop.org/series/165330/ >>> >> >> It doesn't look like __GFP_NORETRY, __GFP_RETRY_MAYFAIL, __GFP_NOFAIL >> make it to the sc->gfp_mask flags from the caller and get into kswapd >> loop... > > Perhaps that's because they mostly (only?) make sense from direct > reclaim? Looks like the trace is from kswapd. kswap obtains the desired order through pgdat->kswapd_order, as a hint from allocation code (wakeup_kswapd). The order can be easily merged (just use the max) We do have the gfp_flags there, but merging them from different wakeups is a bit more tricky (and when to reset?). Assume we have one urgent request for order-0 and one non-urgent (noretry,nofail, ...) request for order-9, we'd have to figure out a way how to represent that. Gets more complicated for more orders. Of course, we could have some kind of array, and try to store some "priority" per order. But I assume plumbing that into the rest of kswapd might not be that easy. -- Cheers, David