From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCC0C621 for ; Thu, 5 Sep 2024 00:31:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725496308; cv=none; b=iRq7aac78nXaexnzVb4bwcdfQiyhK5MGMoiwn6vYMjKodf07atdJ+p4oouYAL2h5vNTmIgCM9cPFP1c8y3yvL2E2ie+BDZxLexQXy7r2/NbwJto9L8tttGIcUz2wd/+sedQFFwbeWKQmY1JUnClSaL+Wg+/lb7cnDL0DeC5/jog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725496308; c=relaxed/simple; bh=dZTE30XsT2qtq5FQUXzNfU44xsB9Bt9PuIDD2SYkgNk=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=Ihc1Am7/PMsyMf7Cks4kdQo4hRw82lhWP4Brw3DSPPTadWGjMOjBEYW4kAE4TlMuiYgqyB5PsoRc8D0b5nBXXbyKkoWSTsgGcxSmcezFR/QmNtTBJp2mUd+MGVlNw8Hjzf/mnEToAQgXre4TntLimueGKW5MK9X+vxRz6pwZ+H4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--kinseyho.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=0zyGFcg2; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--kinseyho.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="0zyGFcg2" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-20206086d92so2927865ad.2 for ; Wed, 04 Sep 2024 17:31:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1725496306; x=1726101106; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=dCiOKpOFqlD6C2iCSSs7Lyoq3x0IlMR0Jw1jQQmJ13E=; b=0zyGFcg2TZ13LdNPT04Eb5mjJBWxR6VmvT162m+aKW9FKuJV51dGZJqjiqO0a3naPC 2LZK8THd9fz75zrpJxvZe0kXrwwD0g08ZXHW/bxWbdpH6bYce6Ix4k4R6ChgtepETglN sKYx9sE1EhM1CHGw6N3zzSK5vwSiZ5jxVlNxiUFbH/Ryca2GbA+wlXB28+NBUj1l/2Ii 4XoJ3VlxPr5s+dTc4HqsLZTEuZHnIVWHntgnZo8Rdy1EZGlwmA87hbiz6UCLlDS7mupi 3teVE16QOhjWVBJvYh670mEl+kqjdVIPtfoDt9/Deg7Cj1ApoUYRq3uBC4NcLkvpjAPu vhKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725496306; x=1726101106; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=dCiOKpOFqlD6C2iCSSs7Lyoq3x0IlMR0Jw1jQQmJ13E=; b=QINlFfOJZjuxiwY/zjNgfP9ZAeHnDqh7EEo+CyTwlI6oaQORbIf63Rc27rl5SjLaDa FtHACzJMzQdyetVVoUFwjZrh78+DWUB42+R+xVDtzEy6iyk1YjRCXsUKv0vnVBrYqQQK 8QXBAPrCswGL9MIC2AbZec0G/Q5x5FWFmyeZ4sCg0iJXmI0Paf3hxmYKO9SKjvWkxdc0 ng5wGwBetIjVI71vSczJiVyhYe63onh8A6sK5oFEOJ02F/PHNSCRnwHhJkQWdn77ivGt u8d7E13kUZEBLSvj3iZUbgvtf5czzb16WhevmNYR0GEV3DXeyz0uCw5OgKUXJHk2fbBB OLlQ== X-Forwarded-Encrypted: i=1; AJvYcCWfoopsk/3/rYrU6GRDz7amjUQ+fIIY0IHrQoJB5bsFK2dvBF3LBMYPiZ6rTeWP2sv4RJP4FMEzUgOoo74=@vger.kernel.org X-Gm-Message-State: AOJu0Yz+jt/Vf1PEPl4DIfazI5TRC88K93pILKGbP32b21GuVMTODryr aK1q7prJMuk+vzFRBe9Chk4WC31ZQ5jYM4Pw8f059JuU49A6xz4dqyZuOp3jvm/s5NtnnWq3kv3 +lfC8hHY8gw== X-Google-Smtp-Source: AGHT+IHGHiTuciDfvv/IhVf91ROgyhWylO6eINXSVTS1ZmC1WL6d+mazuFmoRnQz+5tklBVZyYGtt0yYpGER1A== X-Received: from kinseyct.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:46b]) (user=kinseyho job=sendgmr) by 2002:a17:902:e84b:b0:205:5550:f34f with SMTP id d9443c01a7336-2055550ff57mr10546555ad.6.1725496306005; Wed, 04 Sep 2024 17:31:46 -0700 (PDT) Date: Thu, 5 Sep 2024 00:30:49 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.46.0.469.g59c65b2a67-goog Message-ID: <20240905003058.1859929-1-kinseyho@google.com> Subject: [PATCH mm-unstable v4 0/5] Improve mem_cgroup_iter() From: Kinsey Ho To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Yosry Ahmed , Roman Gushchin , Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Tejun Heo , Zefan Li , mkoutny@suse.com, "T . J . Mercier" , Hugh Dickins , Kinsey Ho Content-Type: text/plain; charset="UTF-8" Incremental cgroup iteration is being used again [1]. This patchset improves the reliability of mem_cgroup_iter(). It also improves simplicity and code readability. [1] https://lore.kernel.org/20240514202641.2821494-1-hannes@cmpxchg.org/ --- v4: Fixed memcg restart bug reported by hughd in v3, patch 4/5 v3: https://lore.kernel.org/20240827230753.2073580-1-kinseyho@google.com/ Removed __rcu tag from patch 2/5 which removes the need for rcu_dereference(). This helps readability. v2: https://lore.kernel.org/20240813204716.842811-1-kinseyho@google.com/ Add patch to clarify css sibling linkage is RCU protected. The kernel build bot RCU sparse error from v1 has been ignored. v1: https://lore.kernel.org/20240724190214.1108049-1-kinseyho@google.com/ Kinsey Ho (5): cgroup: clarify css sibling linkage is protected by cgroup_mutex or RCU mm: don't hold css->refcnt during traversal mm: increment gen # before restarting traversal mm: restart if multiple traversals raced mm: clean up mem_cgroup_iter() include/linux/cgroup-defs.h | 6 ++- include/linux/memcontrol.h | 4 +- kernel/cgroup/cgroup.c | 16 +++---- mm/memcontrol.c | 84 ++++++++++++++++--------------------- 4 files changed, 51 insertions(+), 59 deletions(-) -- 2.46.0.469.g59c65b2a67-goog