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 AB96040EBAD; Wed, 15 Jul 2026 13:16:36 +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=1784121400; cv=none; b=TeZmNYH8qE4kPT9fM+qXOfscLr2fBlcsSL8Aa5fpT3oK1U/kgHR/QbKwFzU3fbYMF4k3W4fx6WZg1EujtsQ/LD7gt3a3wJHH4u+1Py+PRrYIXLlQUwL6+hRSePee2G5ImKSpXX2DvdkCRjLZKjRU+zIyXUbJnDzF8C0Ec59KbhA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784121400; c=relaxed/simple; bh=Kw4qNJiriDvmXjMEsDH+w7ghSOhjZ3L5XXQ39XhO05E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QJ3zaJBETVje+OCK8xvK7nZwqcReZqdgQxX59G81eUxd2xFHo1bau2wV7Hroug+5gO3rbhshLTwOAWly3mkyXjtoodsKp8bfd0Xp+vmQ5fNUoWMjiMnpfxyHn5Yj3gf6E5+Uo8JJteOIJ+WyMMfR+FVQygjoJwMlk6GF1kNzKL8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ok3JXN6g; 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="Ok3JXN6g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5106F1F000E9; Wed, 15 Jul 2026 13:16:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784121394; bh=L/blMt7c0/x/SOLABbbNCJG/CCPLnSKvmx9YqzzFQVA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Ok3JXN6gpujiV3WYE7zP0r0lt52trOjQDdcE9kNKvTHziuUZHP3P4fzdSoFmnaqQS jOkSXWvZPIfENSuklm7MShw6mNUQEosX9cteCzZKvFlab6DjYc27FmT16HaVRcN3e6 wHrPVvSQNCVRKXbzh7NMwRN++gjPwOKO6MAYrTCqX4rdLA6l3cVycxT3rz4RizFbbM RKxa0OFzfReAQ7iRnxMCkjz5JR3QYN+cShFG0hjbYv38Hk/NG6lMMijhaWC09xwgDz Yf4iZ3zlV7bW8eEYbUpy3ye+L1QxYG86m6QfismhI/EWkC9MoZ0rT/ysFdQ5Osu0I6 DRMUAcWKev7Vw== Message-ID: Date: Wed, 15 Jul 2026 15:16:28 +0200 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/4] cgroup/cpuset: update some comments about the page allocator Content-Language: en-US To: Brendan Jackman , Andrew Morton , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Waiman Long , Ridong Chen , Tejun Heo , =?UTF-8?Q?Michal_Koutn=C3=BD?= , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-rt-devel@lists.linux.dev References: <20260715-spin-trylock-followup-v3-0-fc4d246f705d@google.com> <20260715-spin-trylock-followup-v3-2-fc4d246f705d@google.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260715-spin-trylock-followup-v3-2-fc4d246f705d@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/15/26 13:03, Brendan Jackman wrote: > These comments describing the page allocator are out of date: > > - __alloc_pages() is no longer a public API and has no business being > described outside of mm/. > > - The `wait` variable is gone. > > It may be out of date for other reasons too but this patch is just > fixing the issues that stood out. > > To fix it: > > - Instead of referring to a specific function, instead to "the page > allocator" > > - Completely drop out-of-date details of that function's internal > behaviour, since they were irrelevant anyway. > > Suggested-by: Zi Yan > Link: https://lore.kernel.org/all/DJP11T5V7BDW.2FZZZ8R6LOY4I@nvidia.com/ > Reviewed-by: Zi Yan > Signed-off-by: Brendan Jackman Reviewed-by: Vlastimil Babka (SUSE) > --- > kernel/cgroup/cpuset.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 24ea2d09cdbdb..dfd0f827e3b92 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -4193,7 +4193,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) > * nearest enclosing hardwalled ancestor cpuset. > * > * Scanning up parent cpusets requires callback_lock. The > - * __alloc_pages() routine only calls here with __GFP_HARDWALL bit > + * page allocator only calls here with __GFP_HARDWALL bit > * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the > * current tasks mems_allowed came up empty on the first pass over > * the zonelist. So only GFP_KERNEL allocations, if all nodes in the > @@ -4206,11 +4206,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) > * come before the __GFP_HARDWALL check, otherwise a dying task > * would be blocked on the fast path. > * > - * The second pass through get_page_from_freelist() doesn't even call > - * here for GFP_ATOMIC calls. For those calls, the __alloc_pages() > - * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set > - * in alloc_flags. That logic and the checks below have the combined > - * affect that: > + * The second pass through get_page_from_freelist() doesn't even call here for > + * GFP_ATOMIC calls. That, and the checks below have the combined affect that: > * in_interrupt - any node ok (current task context irrelevant) > * GFP_ATOMIC - any node ok > * tsk_is_oom_victim - any node ok > @@ -4327,8 +4324,8 @@ void cpuset_nodes_allowed(struct cgroup *cgroup, nodemask_t *mask) > * should not be possible for the following code to return an > * offline node. But if it did, that would be ok, as this routine > * is not returning the node where the allocation must be, only > - * the node where the search should start. The zonelist passed to > - * __alloc_pages() will include all nodes. If the slab allocator > + * the node where the search should start. The zonelist used by > + * the allocator will include all nodes. If the slab allocator > * is passed an offline node, it will fall back to the local node. > * See kmem_cache_alloc_node(). > */ >