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 6AFABCA0FED for ; Fri, 5 Sep 2025 21:21:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 529998E0006; Fri, 5 Sep 2025 17:21:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 500F98E0001; Fri, 5 Sep 2025 17:21:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 43DE98E0006; Fri, 5 Sep 2025 17:21:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 355C08E0001 for ; Fri, 5 Sep 2025 17:21:05 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D1FB5C0342 for ; Fri, 5 Sep 2025 21:21:04 +0000 (UTC) X-FDA: 83856466848.13.189A952 Received: from out-176.mta1.migadu.com (out-176.mta1.migadu.com [95.215.58.176]) by imf23.hostedemail.com (Postfix) with ESMTP id 0E55914000D for ; Fri, 5 Sep 2025 21:21:02 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=T92UJ6nl; spf=pass (imf23.hostedemail.com: domain of roman.gushchin@linux.dev designates 95.215.58.176 as permitted sender) smtp.mailfrom=roman.gushchin@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=1757107263; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=osQ9Lif183itocSuB65QNUmR7DDdBX3nJ25Dd19v7/A=; b=RDGLzdYj9jdxSHWi61YufRvI4A+GGi6a0Hkml4ZNBfci4X1RVIvOzJwby9uUtTXmLGWkcD aS/Yho0psAKnF5D16YekyNzm3gqX8f5cKd3aWn6ktX/4xswEWclMzFvVHJmFFiS2DHAfjV mkZSp7WqP70xGJZB1JRlaZ04NomJk40= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=T92UJ6nl; spf=pass (imf23.hostedemail.com: domain of roman.gushchin@linux.dev designates 95.215.58.176 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1757107263; a=rsa-sha256; cv=none; b=iKz/TXSya7i+Bww3V9HLmXZ6sNn9dXwZMZtDEoOteCbgO53NKWJiQwfmAutT0uJPPHBQZe PElNkuUWjKm6akFM6+kGLS7S8ZBYrCyAoeLvXGZOCpmoc6TYQL6D0JhBDWjt+eXqe0nmMV mN4GKiOUgNmC/yu2JSMimZxPRtb3U+c= 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=1757107260; 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: in-reply-to:in-reply-to:references:references; bh=osQ9Lif183itocSuB65QNUmR7DDdBX3nJ25Dd19v7/A=; b=T92UJ6nlCLVsFWAjC543fR6YxZ7eSKX4N/EozztC9mQXQQZDNQpa1JqppUr7HfB/1DqVC1 eMMGdMAl5kM/wbqM9bnCE4A7yj8zaOMAzfc1girqTcnRs2VN1F4AGpd0+z+Rm87itDCCbG IVdmYsC+5yZnrIvGVfOGBtML1s5j1Pg= From: Roman Gushchin To: Shakeel Butt Cc: Andrew Morton , Tejun Heo , Johannes Weiner , Michal Hocko , Muchun Song , Alexei Starovoitov , Peilin Ye , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH] memcg: skip cgroup_file_notify if spinning is not allowed In-Reply-To: <20250905201606.66198-1-shakeel.butt@linux.dev> (Shakeel Butt's message of "Fri, 5 Sep 2025 13:16:06 -0700") References: <20250905201606.66198-1-shakeel.butt@linux.dev> Date: Fri, 05 Sep 2025 14:20:46 -0700 Message-ID: <87y0qsa95d.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 0E55914000D X-Stat-Signature: esa86rra83zxxkk4pkehrobu7nfwhngo X-Rspam-User: X-HE-Tag: 1757107262-765122 X-HE-Meta: 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 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: Shakeel Butt writes: > Generally memcg charging is allowed from all the contexts including NMI > where even spinning on spinlock can cause locking issues. However one > call chain was missed during the addition of memcg charging from any > context support. That is try_charge_memcg() -> memcg_memory_event() -> > cgroup_file_notify(). > > The possible function call tree under cgroup_file_notify() can acquire > many different spin locks in spinning mode. Some of them are > cgroup_file_kn_lock, kernfs_notify_lock, pool_workqeue's lock. So, let's > just skip cgroup_file_notify() from memcg charging if the context does > not allow spinning. Hmm, what about OOM events? Losing something like MEMCG_LOW doesn't look like a bit deal, but OOM events can be way more important. Should we instead preserve the event (e.g. as a pending_event_mask) and raise it on the next occasion / from a different context? Thanks