From nobody Mon Feb 9 08:56:08 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F41BC7619A for ; Thu, 23 Mar 2023 04:01:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230333AbjCWEBG (ORCPT ); Thu, 23 Mar 2023 00:01:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbjCWEAx (ORCPT ); Thu, 23 Mar 2023 00:00:53 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6BC31F935 for ; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id q30-20020a17090a17a100b0023d376ac2c5so321244pja.5 for ; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679544045; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0V6KepxSWjC0U8YUMhyf5sEsW80RflfKR4tDJnFyjUM=; b=nvFwhwj7qGyMPQaTPrzYFw+T0XNSe66OQzM5b4pjwLTwVBRy9Yg/AbwpYFnRMIM5gG L465fbRhjctsBw/iYduTrtP7LUUTB2pfnwQVaagEQM0GyAtfd40drA654+PpJ27hrtIB BUWcp/c32KQ98SFLCZ9FSHYNM6vaide1p2wRQYwdJvG/bU3/l2g1YAjLINeXoxbcrV2W 3/G5Y/6fhAJDfUsgxXfVWzP78YqVFCMwh/+/7IKP9AVvA+7qfhsyQkLxneMASA+CreO0 VfuwrktKMl3lyTDdGpOXeKO210ebUx1dz4XnfSvMg+6i1Ne/G/0TP1oqkrL/txGwmyNx VJtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679544045; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0V6KepxSWjC0U8YUMhyf5sEsW80RflfKR4tDJnFyjUM=; b=skSkR8VeGDk8/cPLOKpeLz72fuFTI2Mx2D6WBrEWdgxndtyLX5cD+OjZurGodx7iP3 srlm2HgSC03MUFYjVq/PTL2XHG9GacsKrtjPb6iYVeyrbwMksFBpzB7SiD+2K2tLbSYG nkXZcsBZyigtsEtk8Qlo2XcKX/jHj1LaFU1vgT93n7tGnl2uNkD/CwHQT6Mm0MnWAMjx apTIjIjXnmas4mM0PNKCYvOxbz+MVQi6l+LuycS+kCDEVSjTPRQdoHpnuwlY+AP8UBvu W3sH5RYvdbIzeS2Pv5xllahnNHxjl0xkoCkZnBJi+ZMj3WuIay40ueyz56atMolvUs09 FBsA== X-Gm-Message-State: AO0yUKWcEclZ5Y9ZVwAobIcGzKLmbg0FLaQrMjoQC/he5Dznj4pNcOQU 8fFnTZwJFthtse1ZB7u+RZeGywye7gi0qoCT X-Google-Smtp-Source: AK7set+NjW/4AXEB5d0IG7XiVNOSp7doL59qiTn9uvLqiFnoG/BqWGCoWZHV7SR3pQA/2uxuP1t6d8Miz+ziUaX1 X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6a00:851:b0:628:30d:2d2f with SMTP id q17-20020a056a00085100b00628030d2d2fmr2879444pfk.5.1679544045305; Wed, 22 Mar 2023 21:00:45 -0700 (PDT) Date: Thu, 23 Mar 2023 04:00:32 +0000 In-Reply-To: <20230323040037.2389095-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230323040037.2389095-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.rc1.284.g88254d51c5-goog Message-ID: <20230323040037.2389095-3-yosryahmed@google.com> Subject: [RFC PATCH 2/7] memcg: do not disable interrupts when holding stats_flush_lock From: Yosry Ahmed To: Tejun Heo , Josef Bacik , Jens Axboe , Zefan Li , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton Cc: Vasily Averin , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The rstat flushing code was modified so that we do not disable interrupts when we hold the global rstat lock. Do the same for stats_flush_lock on the memcg side to avoid unnecessarily disabling interrupts throughout flushing. Since the code exclusively uses trylock to acquire this lock, it should be fine to hold from interrupt contexts or normal contexts without disabling interrupts as a deadlock cannot occur. For interrupt contexts we will return immediately without flushing anyway. Signed-off-by: Yosry Ahmed --- mm/memcontrol.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5abffe6f8389..e0e92b38fa51 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -636,15 +636,17 @@ static inline void memcg_rstat_updated(struct mem_cgr= oup *memcg, int val) =20 static void __mem_cgroup_flush_stats(void) { - unsigned long flag; - - if (!spin_trylock_irqsave(&stats_flush_lock, flag)) + /* + * This lock can be acquired from interrupt context, but we only acquire + * using trylock so it should be fine as we cannot cause a deadlock. + */ + if (!spin_trylock(&stats_flush_lock)) return; =20 flush_next_time =3D jiffies_64 + 2*FLUSH_TIME; cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup); atomic_set(&stats_flush_threshold, 0); - spin_unlock_irqrestore(&stats_flush_lock, flag); + spin_unlock(&stats_flush_lock); } =20 void mem_cgroup_flush_stats(void) --=20 2.40.0.rc1.284.g88254d51c5-goog