From nobody Wed Apr 15 01:30:09 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 11FDBC04A68 for ; Thu, 28 Jul 2022 09:14:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235302AbiG1JOA (ORCPT ); Thu, 28 Jul 2022 05:14:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233460AbiG1JN6 (ORCPT ); Thu, 28 Jul 2022 05:13:58 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C144655A6 for ; Thu, 28 Jul 2022 02:13:56 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id e132so1076838pgc.5 for ; Thu, 28 Jul 2022 02:13:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id; bh=ifRf6yNz0UpoCdtj88m7UxYW0lnEYEGGWf6UZFMfb/E=; b=UMqibFaMrO5UXXc8EmGsrmHmsXBzZWIjYQFhNtKcGhReIxfLEjWuotzgbVuqFLKaKG oR41b2bJne+sypFSCzu1sNaRAkUjHOEX6c5s5yQpVHXvfiY8iAKr1Z8HCpE/KgA1kP/A Qm7NH7hwlT8hk/qQssIeurA63moDyca2WTF5fC+sy49l/fQhOFpq1rxM0+izAvXIhrls eL1GUmFU6aPvT2gGUeOiiuqve9QsYIGxWaKT0o3WRPZwDx9rkNI3uh4RvRb30zZ+dMtN P5akBKRCBKLAhdOv/WxJmvPrsI0B0seshkcQgsMy9fPZup4XS8zMuhmdVy3GUnuVajNw 0Whg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=ifRf6yNz0UpoCdtj88m7UxYW0lnEYEGGWf6UZFMfb/E=; b=2tsoot/8Dn0LBrUrAwzqf2nt0iOttwfV6rHFxU0zbu592HSB4F+/aIN/B0qUw9awTB 4OXsZTq12E9DjBN85W6biOBlDIbsOEP4aTtM/7tvxyO94/YSmofP4Sq4WnESdV08EOY+ QV/xngMLtAH1z2VdigA330Ed6VukbpKZHGFO/Yy6EOsHtuL4tpwU+zV++j9Jp2w0ivTY tzvYXcVATfi9SvfZxGiJdYloc3LpqF72HXFiM+uc/KJSteGeDWFSue3KW1Cw70HSjqnX 4IdQDJngwpldmO+L2J2W8XtZ8P371X2ENtMtZBrOXwzwvN7JkyfXm8fVIEV3jqN56XIg sWhQ== X-Gm-Message-State: AJIora+a4ZAVOxuvaSb2mlqB6nmRCAbRSeFlfXeM9Eehlp/MXd337sx5 VuOoni/tpJ8cJ9JLPoTX3K4zkA== X-Google-Smtp-Source: AGRyM1saXjIwDHTO2NzoOk4vH/43+tdtVnUn9lT05MVWU6gR2I3it/u7NGRbP5+s7pvSWimGAexQXg== X-Received: by 2002:a05:6a00:2190:b0:52b:fe5f:5939 with SMTP id h16-20020a056a00219000b0052bfe5f5939mr16525576pfi.83.1658999636171; Thu, 28 Jul 2022 02:13:56 -0700 (PDT) Received: from n131-251-112.byted.org ([121.30.179.115]) by smtp.gmail.com with ESMTPSA id p9-20020a170902e74900b0016dc2366722sm681304plf.77.2022.07.28.02.13.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Jul 2022 02:13:51 -0700 (PDT) From: tujinjiang@bytedance.com To: mhocko@suse.com Cc: shy828301@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jinjiang Tu Subject: [PATCH v2] vmscan: Do not free nr_deferred for memcg aware shrinkers Date: Thu, 28 Jul 2022 17:13:41 +0800 Message-Id: <20220728091341.20820-1-tujinjiang@bytedance.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Jinjiang Tu When a memcg aware shrinker is registered by register_shrinker(), shrinker->nr_deferred will not be initialized. But when the shrinker is unregistered by unregister_shrinker(), shrinker->nr_deferred will be freed. Luckily, the memcg aware shrinkers in the current kernel are pre-zeroed. But a new memcg aware shrinker may be added in the future, and we should not assume the shrinker is pre-zeroed. Another unregister API free_prealloced_shrinker() does not assume the shrinker is pre-zered and free shrinker->nr_deferred only if it is not memcg aware. So unregister_shrinker() should do like free_prealloced_shrinker(). Signed-off-by: Jinjiang Tu --- mm/vmscan.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index f7d9a683e3a7..f8a9a5349b6e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -675,8 +675,11 @@ void unregister_shrinker(struct shrinker *shrinker) down_write(&shrinker_rwsem); list_del(&shrinker->list); shrinker->flags &=3D ~SHRINKER_REGISTERED; - if (shrinker->flags & SHRINKER_MEMCG_AWARE) + if (shrinker->flags & SHRINKER_MEMCG_AWARE) { unregister_memcg_shrinker(shrinker); + up_write(&shrinker_rwsem); + return; + } up_write(&shrinker_rwsem); =20 kfree(shrinker->nr_deferred); --=20 2.17.1