From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F304CC43458 for ; Tue, 14 Jul 2026 11:31:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EF7A46B0092; Tue, 14 Jul 2026 07:31:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ECEDB6B0093; Tue, 14 Jul 2026 07:31:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E0C726B0095; Tue, 14 Jul 2026 07:31:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B00DB6B0092 for ; Tue, 14 Jul 2026 07:31:30 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 31BBE14032C for ; Tue, 14 Jul 2026 11:31:30 +0000 (UTC) X-FDA: 84987166740.06.4CF1882 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) by imf23.hostedemail.com (Postfix) with ESMTP id CFAE0140004 for ; Tue, 14 Jul 2026 11:31:26 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=aubsTbCz; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf23.hostedemail.com: domain of ridong.chen@linux.dev designates 91.218.175.179 as permitted sender) smtp.mailfrom=ridong.chen@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784028687; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=zwhrkQgNNnztcrozTTZGeAnrDC8vAtQeya0vh3r35g4=; b=sc5eslj4diQoH1XfKSVs80rsjt+9+XWJ2J6PB5BYGFI89aLcOfZVmvZX50ES24vnh1ComS PpVmE7YTNDpgUAm8pC3pWQTaISWB+RhfKJPJsZ7afaowQCMq0UnEbh7tdVIvbf3A1LUa3k osUOfrzCcBHaKk/m4ys0he2TquJpdhw= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=aubsTbCz; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf23.hostedemail.com: domain of ridong.chen@linux.dev designates 91.218.175.179 as permitted sender) smtp.mailfrom=ridong.chen@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784028687; b=OMgre4Gca23+YzkPJesMcvYRHBS57etIlwvTblNTPtiU9Tv4UR0i2f/LcuZarUhFXMypVD t1I5ecNJkAs1/gJqgR2jCqPmzlmfqJIHULGbctpWB2V36O3GBipOFjxBaA7Gs2SHM1jNYn 8yOvJ0niKyxXj8BtpHfTPmC5ungJrFs= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784028683; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zwhrkQgNNnztcrozTTZGeAnrDC8vAtQeya0vh3r35g4=; b=aubsTbCz2J03ebsHx5YMNPz+vCnRTn2SVDUHzV4RWAcoPSGngHtReBCmi1/XyTh4KGbt8A 72hx/ld7+39lC45i4jqGr1WlT4lLcu/Rkvyu7Xj+/pjRSGYywHARH9pvG50tCZrLWq5EMW pyoqFG4tdKTLCW8zpowzsqFvlGyB/GM= Date: Tue, 14 Jul 2026 19:31:05 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 1/2] memcg: move mem_cgroup_swappiness to memcontrol.h To: Barry Song Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Chris Li , Kairui Song , David Hildenbrand , Yuanchu Xie , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Ridong Chen References: <20260711091157.306070-1-ridong.chen@linux.dev> <20260711091157.306070-2-ridong.chen@linux.dev> <87dc4105-b98b-4541-bafe-c0adfbf58836@linux.dev> <0545ee70-b0a0-4a93-ac2c-3e84ff504e5a@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Ridong Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: sdhrrnwk9i1a5hkbsnu3i4pdx8kkqrfh X-Rspamd-Queue-Id: CFAE0140004 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1784028686-327139 X-HE-Meta: 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 3oziqG3H k9cTLASuSvgg2MmwW9MJz36PvLh7etH+oC/UFZ8q82sZQmi16KqHkG23G31xyq5UqoEEE3JAKDJiz8NNK/qJ47Wl9rkD8wkD87jYrM7ZuK1dsBmd1QVSBtJKxBVdBAZNp53eWGSy7LmP6PuXv9Fo3woIf3WDEDRIf5A9JB3zdP0iQ19OG4KmLo09Es8AJRzqApIqIFE1VeW8Ad1veCDoJWd9rr6jTbEwEfm+EUpqwFDDSeztqfNTqwYNlZgKsS0ox2OxMaTejJrrCCt3tAjT7OmjtRZju1Qm+PgrJofRMyc7C/iP/I4PkZjbLkSsF2UxtNtr96oLb4RnFQFu+ROEtrBHw4aLYtvFQLIONWsCxlvYiSGiNVZMDtGDWsXIPAulbJyUr1V8OVmlWzAzNlNUGgWxHu7lvk/qwLvWG Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/14/2026 6:21 PM, Barry Song wrote: > On Tue, Jul 14, 2026 at 3:43 PM Ridong Chen wrote: >> >> >> >> On 7/14/2026 9:48 AM, Barry Song wrote: >>> On Tue, Jul 14, 2026 at 9:43 AM Barry Song wrote: >>>> >>>> On Tue, Jul 14, 2026 at 9:20 AM Ridong Chen wrote: >>>>> >>>>> >>>>> >>>>> On 7/13/2026 11:08 PM, Barry Song wrote: >>>>>> On Sat, Jul 11, 2026 at 5:12 PM Ridong Chen wrote: >>>>>>> >>>>>>> From: Ridong Chen >>>>>>> >>>>>>> The per-memcg swappiness knob is v1-only; v2 always uses global >>>>>>> vm_swappiness and ignores the per-cgroup field. >>>>>>> >>>>>>> Guard memcg->swappiness with CONFIG_MEMCG_V1, and move the helper >>>>>>> to memcontrol.h where it belongs. >>>>>>> >>>>>>> No functional change for v1; v2-only kernels drop the unused field. >>>>>>> >>>>>>> Signed-off-by: Ridong Chen >>>>>>> Acked-by: Johannes Weiner >>>>>> >>>>>> Reviewed-by: Barry Song >>>>>> >>>>>> With some nits. >>>>>> >>>>>>> --- >>>>>> [...] >>>>>>> struct mem_cgroup_per_node *nodeinfo[]; >>>>>>> @@ -365,6 +366,9 @@ enum objext_flags { >>>>>>> >>>>>>> #define OBJEXTS_FLAGS_MASK (__NR_OBJEXTS_FLAGS - 1) >>>>>>> >>>>>>> +/* Defined in mm/vmscan.c; used by mem_cgroup_swappiness(). */ >>>>>>> +extern int vm_swappiness; >>>>>> >>>>>> This is a bit unusual. I'm not sure whether mm/swap.h would be >>>>>> a more appropriate place for this. >>>>>> >>>>> Thank you for your reply. >>>>> >>>>> The vm_swappiness variable is not utilized within mm/swap.c. >>>>> Furthermore, since memcontrol.h does not include swap.h, retaining the >>>>> extern int vm_swappiness declaration in mm/swap.h will result in a >>>>> compilation failure. >>>> >>>> If this is the case, it still seems better to keep >>>> extern int vm_swappiness in include/linux/swap.h. >>>> >>>> Then we don't need the comment: >>>> /* Defined in mm/vmscan.c; used by mem_cgroup_swappiness(). */ >>>> >>>> It also makes it clearer that vm_swappiness is an extern variable >>>> belonging to the swap module, rather than the memcontrol module. >>> >>> BTW, if mem_c_group_swappiness() and vm_swappiness are only used >>> within mm/, could all of these be moved to mm/swap.h and >>> mm/internal.h instead? >>> >>> We are making a big effort to move many unrelated things out of >>> include/linux/swap.h recently. Could you check? >>> >>> https://lore.kernel.org/linux-mm/20260708-ch-swap-series-plus-folio-lru-cleanup-v9-0-2bc72b4f8730@gmail.com/ >> >> Good suggestion. Moving them to mm/internal.h makes sense. Will update >> in the next version. > > Either mm/swap.h or mm/internal.h. > vm_swappiness probably belongs in mm/swap.h rather than > mm/internal.h, right? > > BTW, I am not particularly eager about this cleanup; > it could be done later as a separate patch. > > If you decide not to do the cleanup, I think it would be better to > leave "extern int vm_swappiness" in include/linux/swap.h rather than > declaring it in include/linux/memcontrol.h? I noticed that some swap-related macros are already defined in mm/internal.h, so I'm planning to place the code right after them for better grouping. Does that work for you? ``` ... #define MEMCG_RECLAIM_MAY_SWAP (1 << 1) #define MEMCG_RECLAIM_PROACTIVE (1 << 2) #define MIN_SWAPPINESS 0 #define MAX_SWAPPINESS 200 /* Just reclaim from anon folios in proactive memory reclaim */ #define SWAPPINESS_ANON_ONLY (MAX_SWAPPINESS + 1) extern int vm_swappiness; static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) { #ifdef CONFIG_MEMCG_V1 /* Cgroup2 doesn't have per-cgroup swappiness */ if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return READ_ONCE(vm_swappiness); /* root ? */ if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg)) return READ_ONCE(vm_swappiness); return READ_ONCE(memcg->swappiness); #else return READ_ONCE(vm_swappiness); #endif } ... ``` -- Best regards Ridong