From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6767E372063; Wed, 1 Jul 2026 16:54:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782924898; cv=none; b=mWgSjkO+roRQQ+Vg5ewTfbME4AOegP9myfluDVN076ijjkiO6zC9H9daDgtuc4G9y1bZiFZ3sicwCgKngy0vJdcsvK4kNsVy2Q8WnQlBUoJxRdGzk7GH9jxu7pSBJ9QMiZTrxzhX/3Z0MLtZusJuG/iebI8HUL2ofNrtI9/2DJQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782924898; c=relaxed/simple; bh=7l9gIHgifJoMN3zoS9PXdp7hn8eP6N9EERRtvi9nqk0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=IwRVJOpB3RkcVRMs4XWMGS+sgyEIIQyL50KusD43/UuOihqXzGFr5IB75xG92lfDeGBNMRZF5hG//GccKnZjo9ZWsV40QrAfTmATvLW7VxTMeH/iX8HQQU2AMsJFdviNLE0G6Pw1tQiGakcLiGwQL4hQofCEbJldPIT58pBQF7A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MIi48hmX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MIi48hmX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25E881F000E9; Wed, 1 Jul 2026 16:54:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782924897; bh=87Wni51q7tV3DEcX7N0ywWkBdDM6S1XyRH7FSeJhsxg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=MIi48hmXsvy9gv6zAWRL5MXmswZhWZ0M1QqKS9FFSgETxRmTX2oSFqeGqE2qU5kxG k9280jpyr+SZh9okxydz/S4PDEhFalWWrTJP/ntLSe8r0V21zOn2UlDwojqVFcdpaD yyWSQDMkpPtx5d/6NZvWAggJEGl5tipOWNlOHf3Pta2mG9GhmIt4Diw/gQg+R+gOfk /QYH5/pPDy2FBtljlx1gcdfhfp5Ty2fRnXNHbwg6rVzYbrXUFjn8qPij2nGrnfbgE4 MywQ1ESFcJnXMuWQ0En144bm6nFQOV27fZo894EdmNDXtLGS3mWP40g2X5YldmHHDh WB3BMJhUXFyQA== Message-ID: <43b4c503-14ba-4e88-b56c-caf5ef0597de@kernel.org> Date: Wed, 1 Jul 2026 18:54:52 +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] mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug To: Gregory Price Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, kernel-team@meta.com, osalvador@suse.de, akpm@linux-foundation.org, rppt@kernel.org, mgorman@techsingularity.net, hannes@cmpxchg.org, vbabka@kernel.org References: <20260630214039.2263562-1-gourry@gourry.net> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/1/26 17:05, Gregory Price wrote: > On Wed, Jul 01, 2026 at 10:35:41AM +0200, David Hildenbrand (Arm) wrote: >> >>> * The node we allocated has no zone fallback lists. For avoiding >>> diff --git a/mm/mm_init.c b/mm/mm_init.c >>> index 306ea5c13f54..37fd64ce144d 100644 >>> --- a/mm/mm_init.c >>> +++ b/mm/mm_init.c >>> @@ -1536,7 +1536,7 @@ void __init set_pageblock_order(void) >>> * NOTE: this function is only called during memory hotplug >>> */ >>> #ifdef CONFIG_MEMORY_HOTPLUG >>> -void __ref free_area_init_core_hotplug(struct pglist_data *pgdat) >>> +int __ref free_area_init_core_hotplug(struct pglist_data *pgdat) >>> { >>> int nid = pgdat->node_id; >>> enum zone_type z; >>> @@ -1544,8 +1544,14 @@ void __ref free_area_init_core_hotplug(struct pglist_data *pgdat) >>> >>> pgdat_init_internals(pgdat); >>> >>> - if (pgdat->per_cpu_nodestats == &boot_nodestats) >>> - pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); >>> + if (pgdat->per_cpu_nodestats == &boot_nodestats) { >>> + struct per_cpu_nodestat __percpu *p; >>> + >>> + p = alloc_percpu(struct per_cpu_nodestat); >>> + if (!p) >>> + return -ENOMEM; >>> + pgdat->per_cpu_nodestats = p; >> >> Is there a need for the temporary variable? >> > > at start: > pgdat->per_cpu_nodestats = &boot_nodestats > > So need a tmp to do the swap/revert/etc Reviewing too many patches today ... makes sense. > >> Also how to handle cleanup on error? Or why can we skip cleanup? (what happens >> if we get another call to __try_online_node() later?) >> > > -ENOMEM -> > hotadd_init_pgdat -> NULL > __try_online_node -> -ENOMEM > pr_err("Cannot online node %d due to NULL pgdat\n", nid); > try_online_node -> -ENOMEM > __add_memory_resource -> error_memblock_remove: > > Basically we're left exactly where we were before we made the attempt. > > Another call should work just fine after a bunch of dmesg spew. Okay, so the additional pgdat_init_internals) should be ok. Makes sense to me, thanks. -- Cheers, David