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 883172594BE; Fri, 15 Aug 2025 17:30:30 +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=1755279030; cv=none; b=aa2z4GzsZfkZR1ZnLLx3XY8YKv57pWwokNr3eEuIp5SEpUOb2vADl+iJvOUhQ1BT+1PCBunU06W7Mqv4GWTKz0qw0551YIWLsjMoo1l7WMLhtXvlHQQqCuCzbV/0oIHcT9EjsdJvBcp4mC4M1L8l1MBP5oGVKcB87CtE6MzBT7s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755279030; c=relaxed/simple; bh=46Vhq5B5B8BhfkVAaBvZm6I80x160rOMz23izYCe7nQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=r5vMtB55FwtDH5WqsYgtslFtTtlAgUsp/EsT/emVE5qERI/hT8fv3+tqMgx9LmcRekNYZKSsWcF5i+959SNFUp6OoLOXZo73NMScY0JIPcjIrMOJ27V3/ujBVAxl2hxKyxwEBJavL4OB/ztC237Udm2OK9EkCG1/d71H/SpYP2c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PaR9LgCR; 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="PaR9LgCR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86670C4CEEB; Fri, 15 Aug 2025 17:30:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755279030; bh=46Vhq5B5B8BhfkVAaBvZm6I80x160rOMz23izYCe7nQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PaR9LgCR3Nq8DqCnN0257ae3AWJtEgbd7LbBNcjk3Q5e5xLZtpEhNunt91yFsPi2G vb8RbYLnohJYlXjTYDH6y6v1o7aeT/olP4FuMbkW4MvO6Rtdv7Su0ZJYbh8U/OUX+o njNaGgjJwUwy2owusEOHa6cZwZKKq6hpYwjherCnfLuTRvDQ7JlCnhsuQaNDu8HSde GUtp3tO7tHaTF7Wi61w7Vkv1oCTPa6z6DxN3ZgFjw8tdJGaJr/klp5hvsU+tHzY3Lp xqxNeKLmZv6sbwoHK8ZO5H2kkgJ2pTN2oKWf/37Uuh7l7mihTAouGri8fM9nLoOB5p /HwlEiT3pwi0w== Message-ID: <41ed390c-884e-4158-9fe8-ce3af53cf77b@kernel.org> Date: Fri, 15 Aug 2025 19:30:21 +0200 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH v4 net-next 01/10] mptcp: Fix up subflow's memcg when CONFIG_SOCK_CGROUP_DATA=n. Content-Language: en-GB, fr-BE To: Kuniyuki Iwashima , Shakeel Butt Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Neal Cardwell , Paolo Abeni , Willem de Bruijn , Mat Martineau , Johannes Weiner , Michal Hocko , Roman Gushchin , Andrew Morton , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Tejun Heo , Simon Horman , Geliang Tang , Muchun Song , Mina Almasry , Kuniyuki Iwashima , netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org References: <20250814200912.1040628-1-kuniyu@google.com> <20250814200912.1040628-2-kuniyu@google.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Kuniyuki, On 15/08/2025 19:24, Kuniyuki Iwashima wrote: > On Thu, Aug 14, 2025 at 7:31 PM Kuniyuki Iwashima wrote: >> >> On Thu, Aug 14, 2025 at 6:06 PM Shakeel Butt wrote: >>> >>> On Thu, Aug 14, 2025 at 05:05:56PM -0700, Kuniyuki Iwashima wrote: >>>> On Thu, Aug 14, 2025 at 4:46 PM Shakeel Butt wrote: >>>>> >>>>> On Thu, Aug 14, 2025 at 04:27:31PM -0700, Kuniyuki Iwashima wrote: >>>>>> On Thu, Aug 14, 2025 at 2:44 PM Shakeel Butt wrote: >>>>>>> >>>>>>> On Thu, Aug 14, 2025 at 08:08:33PM +0000, Kuniyuki Iwashima wrote: >>>>>>>> When sk_alloc() allocates a socket, mem_cgroup_sk_alloc() sets >>>>>>>> sk->sk_memcg based on the current task. >>>>>>>> >>>>>>>> MPTCP subflow socket creation is triggered from userspace or >>>>>>>> an in-kernel worker. >>>>>>>> >>>>>>>> In the latter case, sk->sk_memcg is not what we want. So, we fix >>>>>>>> it up from the parent socket's sk->sk_memcg in mptcp_attach_cgroup(). >>>>>>>> >>>>>>>> Although the code is placed under #ifdef CONFIG_MEMCG, it is buried >>>>>>>> under #ifdef CONFIG_SOCK_CGROUP_DATA. >>>>>>>> >>>>>>>> The two configs are orthogonal. If CONFIG_MEMCG is enabled without >>>>>>>> CONFIG_SOCK_CGROUP_DATA, the subflow's memory usage is not charged >>>>>>>> correctly. >>>>>>>> >>>>>>>> Let's wrap sock_create_kern() for subflow with set_active_memcg() >>>>>>>> using the parent sk->sk_memcg. >>>>>>>> >>>>>>>> Fixes: 3764b0c5651e3 ("mptcp: attach subflow socket to parent cgroup") >>>>>>>> Suggested-by: Michal Koutný >>>>>>>> Signed-off-by: Kuniyuki Iwashima >>>>>>>> --- >>>>>>>> mm/memcontrol.c | 5 ++++- >>>>>>>> net/mptcp/subflow.c | 11 +++-------- >>>>>>>> 2 files changed, 7 insertions(+), 9 deletions(-) >>>>>>>> >>>>>>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>>>>>> index 8dd7fbed5a94..450862e7fd7a 100644 >>>>>>>> --- a/mm/memcontrol.c >>>>>>>> +++ b/mm/memcontrol.c >>>>>>>> @@ -5006,8 +5006,11 @@ void mem_cgroup_sk_alloc(struct sock *sk) >>>>>>>> if (!in_task()) >>>>>>>> return; >>>>>>>> >>>>>>>> + memcg = current->active_memcg; >>>>>>>> + >>>>>>> >>>>>>> Use active_memcg() instead of current->active_memcg and do before the >>>>>>> !in_task() check. >>>>>> >>>>>> Why not reuse the !in_task() check here ? >>>>>> We never use int_active_memcg for socket and also >>>>>> know int_active_memcg is always NULL here. >>>>>> >>>>> >>>>> If we are making mem_cgroup_sk_alloc() work with set_active_memcg() >>>>> infra then make it work for both in_task() and !in_task() contexts. >>>> >>>> Considering e876ecc67db80, then I think we should add >>>> set_active_memcg_in_task() and active_memcg_in_task(). >>>> >>>> or at least we need WARN_ON() if we want to place active_memcg() >>>> before the in_task() check, but this looks ugly. >>>> >>>> memcg = active_memcg(); >>>> if (!in_task() && !memcg) >>>> return; >>>> DEBUG_NET_WARN_ON_ONCE(!in_task() && memcg)) >>> >>> You don't have to use the code as is. It is just an example. Basically I >>> am asking if in future someone does the following: >>> >>> // in !in_task() context >>> old_memcg = set_active_memcg(new_memcg); >>> sk = sk_alloc(); >>> set_active_memcg(old_memcg); >>> >>> mem_cgroup_sk_alloc() should work and associate the sk with the >>> new_memcg. >>> >>> You can manually inline active_memcg() function to avoid multiple >>> in_task() checks like below: >> >> Will do so, thanks! > > I noticed this won't work with the bpf approach as the > hook is only called for !sk_kern socket (MPTCP subflow > is sk_kern == 1) and we need to manually copy the > memcg anyway.. so I'll use the original patch 1 in the > next version. Thank you for having checked that! Cheers, Matt -- Sponsored by the NGI0 Core fund.