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 BE5B0CCF9E0 for ; Tue, 28 Oct 2025 14:03:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 28A9F80156; Tue, 28 Oct 2025 10:03:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 23B648013F; Tue, 28 Oct 2025 10:03:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0DCA080156; Tue, 28 Oct 2025 10:03:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id EA98A8013F for ; Tue, 28 Oct 2025 10:03:20 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 9881C13B128 for ; Tue, 28 Oct 2025 14:03:20 +0000 (UTC) X-FDA: 84047690160.28.629D6AB Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) by imf07.hostedemail.com (Postfix) with ESMTP id CD17740014 for ; Tue, 28 Oct 2025 14:03:18 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Keb41diP; spf=pass (imf07.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1761660199; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AQ5H2mz4dVXx5yLN5zTg1jKj+s12XH2F8FoyP4DTscE=; b=UMTuSidKHPcbMHrANlAkgHvGFbBFFYmgFBuXfvrsQgAXTg4K8YpyVRA2iP8v1LoUgqtLTY 72h9HeNJKorPI2Amz4hMrJ8o8prFTVRALoRjMTOvez5JvO48FqhQSZJiXfI/M8j0BzvwCj g2aH7ivuBPuQsSTs2Pqjp2mYfD0zjn8= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Keb41diP; spf=pass (imf07.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.180 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1761660199; a=rsa-sha256; cv=none; b=sdnmopS4OtM3yrrmoMWgYzEAEztehWf3kcGLYdkCCzW5W0uCjCzAP7gk2pUPjEHqTwfb3a CeJ8y5pK+0+2QTKwMqKRPKUEHLmLyr4WnVlwazZ/71Rn+kYkYotUqI2H9fBMWoOvYXnpHU 85lYLVt8UHDKfyCPLf41YvPRPc9UZ18= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761660197; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AQ5H2mz4dVXx5yLN5zTg1jKj+s12XH2F8FoyP4DTscE=; b=Keb41diPvx6YSmv3KjV5tfMFVwgCTvM3vVnU5B8tPPTriLp0WGiAeHuYMTVXp2SxD5lxBu 33n4iaxgrmdpRj6MsPU9h3TczXEoHjcIiBgf6j5GU4SPKcdnBad+SPu7i363kDDpf4bSkC 3R2eVAJrKlZIF4uljuyHmUYjf+6rNsw= From: Qi Zheng To: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v1 10/26] mm: memcontrol: prevent memory cgroup release in count_memcg_folio_events() Date: Tue, 28 Oct 2025 21:58:23 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: CD17740014 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: mxqwdr3jyyu3yi1jy7zbnf7g51xmg4xt X-HE-Tag: 1761660198-657949 X-HE-Meta: U2FsdGVkX1/rn7iRKsIj/HWhO7Lg6aeCa80LliK/Ew2wzU4008psV1S8VzNNqKDhWI8ZKUhn5LEJX4GDA5BQGSLfo+EKOCDA2eZKDkWf2thWi8i22McjWYVC8kDT2yD7wAaOmiSC58pjSIRegP5kRqvSCxlewGO1+GteJjayTsIN++TGUIEFquQmqvMuufaBU0/wWmEdPSuJnc6nQXhfD7OEJl4rhDxJ59Knun2CUBiZ46o0MHAKuzdOB7qqq7jUyquafsAzxyDOrCPwMB8awirmNeVlpOf/ymyWC6oRx0SvyPUHeyq+PnKDmSzuz/JraSGRBMzH3z/zY3p1kYxl55TYvHhivKg+yBBkMRQBR9tLhWZWrqKMb10x6/koOqgw8b8FVZweioslkZ7sq6UT8kgrjJtip6WDForp89naiqCwEmpZWnGTtBhjrYLT2BM7ZdDrcIiamLFqavtHE29ORI21fTRC9hlBhFXcHA/BfkBR3Vuq+mNywU+uAG8G3+9QK0wRKCCeESHsC7mki3SiwfYaqRaOG6cHVPqJTLkMXYcM1JNZelXXgiRaCuLiYr30RDb1sWDsQskgc8v7v61NrDb0iRw2x3IjpNWgPkSWfl+IqU8fKLr/tfEO3tVuL2A5d8+aRzCF7mzGkOnNW/Wfu6iy5zgdgfIFSJGlArlBwZzeg9nrddy/VdAJo19jgtvyJb/k7rN5l6e4O1KkfeC2o4eEYwmZFuc/nxpmaBktbsZSriZz0g0q3jWdYKj76QmeW3IjPjGb+sYa8C64L3qis52rJzmzYBv7GEioLE4305aL0amhfnwWTOHYltit17q3ndMcCnFq8njsNDAS49REauZadXQi8LAhFk6kpElaanBekJuY8GLNa1Eo8rFecSyk75C1e3uqGdtqFzPzr311HjchrEC9vEDM5fDIhKt9Eg9gsYzGM1/AujwydeMZUyZJSkcBzh+Ub1eS4f4elb+ mtS4JtSG NEV7MkijoIHQjI+pHv2ixKC4RFICR2BSHtALeiMNFpXy6TdIDH+ntmQD18sIUr87wo4Ao3KTKWnnyMmsE5Nt5k8CE38B4+CntxavS9lKg4VR5Ab+5tbR3hUsENv8tz1LRjLFwv1GJQ+BylSlugQ/XEByehCISC4WXcFKN+TZ0cmppTHdTR85IoK7csWtfjmGiwKu6DPAp/RW/6NTjO5mTBqJFCqTk10Ax7oEloa2st/C4RF/U8T+seGHtLDVHo34E6vlp+oi3HpGaLitSro+B4+TEOnlVo6kCfFX4CFPpUPFwjiA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Muchun Song In the near future, a folio will no longer pin its corresponding memory cgroup. To ensure safety, it will only be appropriate to hold the rcu read lock or acquire a reference to the memory cgroup returned by folio_memcg(), thereby preventing it from being released. In the current patch, the rcu read lock is employed to safeguard against the release of the memory cgroup in count_memcg_folio_events(). This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Signed-off-by: Qi Zheng --- include/linux/memcontrol.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 174e52d8e7039..ca8d4e09cbe7d 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -984,10 +984,15 @@ void count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, static inline void count_memcg_folio_events(struct folio *folio, enum vm_event_item idx, unsigned long nr) { - struct mem_cgroup *memcg = folio_memcg(folio); + struct mem_cgroup *memcg; - if (memcg) - count_memcg_events(memcg, idx, nr); + if (!folio_memcg_charged(folio)) + return; + + rcu_read_lock(); + memcg = folio_memcg(folio); + count_memcg_events(memcg, idx, nr); + rcu_read_unlock(); } static inline void count_memcg_events_mm(struct mm_struct *mm, -- 2.20.1