From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C8E4B3CAA52 for ; Wed, 15 Jul 2026 11:40:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784115647; cv=none; b=HAgXlZNuaAeV6BvtkLbUs0veImLJtKfCenK2g4i1g/mswD3nbTtVBt+PXWoGqhQK3bY/5fpzPcy7FTbapKspygr2V6zLER+s9nHpN0McMTjNx7UPNjrEos1goaqu4v+AxOWZmJymS3RjLTit+QbMeJM8PkLxiKbqY10YqED7tTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784115647; c=relaxed/simple; bh=aJPszi/WhVbBiKCEv/pkObigBK2rziE+vnR4fu+G3pY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=U/rqrGI3Op9hllHVPjMFFoTgCEAOYqh1CuOr+anWbuwf2I2LtRzgst62aKOBuQnvWPLlu9/A8v/zUmEacva1BRcmK+1mptY6m20ehYgGp2LRdGzvrF1zk0qbj2smlE2E0+nvsgjTPNF/aBrIp7Tlgp0JE+LWBM/9m7tyigJNzs8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QgI2raK1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QgI2raK1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCA7D1F000E9; Wed, 15 Jul 2026 11:40:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784115645; bh=WuJEdrQZcATrQ7CUm0n3hD53dF2v9/by4tZJAjBZdLk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QgI2raK1Y0Tcl/rR/Aw+qp054NBIElSG1bKanzjcL3pS+K8s9mhqpehoiojVgZLkb YjJIzUtd0R5QX6qALucQSEXXpCaju4ZbTcouySC/Fhyrtv/fFbvE2JBU62/AlCh+Lk sC5uOHCmq7U0o2XChMTc0exyEFZeG8SI2GZDlsM1WASF6zUziqqCkklT8rAqzEgJ+u ccxtrd0bGSfXTYnHNzrgxnuSd8Kq6nbgkFs7sRMoCmgggoZqbpmsTsm4NC/ebpY/Wy 1zGRc6JhO/G/4NKtjIXrMt6ID3MI1qtu1FxF591wsU4Obcrg1TBn9okduroIogfvMG utKyShduPV9fw== From: Sasha Levin To: stable@vger.kernel.org Cc: Qi Zheng , Muchun Song , Christian Brauner , =?UTF-8?q?Christian=20K=C3=B6nig?= , Chuck Lever , Daniel Vetter , Daniel Vetter , "Darrick J. Wong" , Dave Chinner , Greg Kroah-Hartman , Joel Fernandes , Kirill Tkhai , "Paul E. McKenney" , Roman Gushchin , Sergey Senozhatsky , Steven Price , Theodore Ts'o , Vlastimil Babka , Abhinav Kumar , Alasdair Kergon , Alexander Viro , Alyssa Rosenzweig , Andreas Dilger , Andreas Gruenbacher , Anna Schumaker , Arnd Bergmann , Bob Peterson , Borislav Petkov , Carlos Llamas , Chandan Babu R , Chao Yu , Chris Mason , Coly Li , Dai Ngo , Dave Hansen , David Airlie , David Hildenbrand , David Sterba , Dmitry Baryshkov , Gao Xiang , Huang Rui , Ingo Molnar , Jaegeuk Kim , Jani Nikula , Jan Kara , Jason Wang , Jeff Layton , Jeffle Xu , Joonas Lahtinen , Josef Bacik , Juergen Gross , Kent Overstreet , Marijn Suijten , "Michael S. Tsirkin" , Mike Snitzer , Minchan Kim , Muchun Song , Nadav Amit , Neil Brown , Oleksandr Tyshchenko , Olga Kornievskaia , Richard Weinberger , Rob Clark , Rob Herring , Rodrigo Vivi , Sean Paul , Song Liu , Stefano Stabellini , Thomas Gleixner , Tomeu Vizoso , Tom Talpey , Trond Myklebust , Tvrtko Ursulin , Xuan Zhuo , Yue Hu , Andrew Morton , Sasha Levin Subject: [PATCH 6.6.y 1/2] mm: shrinker: remove redundant shrinker_rwsem in debugfs operations Date: Wed, 15 Jul 2026 07:40:36 -0400 Message-ID: <20260715114037.728053-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026071317-sandfish-tulip-2010@gregkh> References: <2026071317-sandfish-tulip-2010@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Qi Zheng [ Upstream commit 1dd49e58f966b1eecd935dc28458a8369ae94ad1 ] debugfs_remove_recursive() will wait for debugfs_file_put() to return, so the shrinker will not be freed when doing debugfs operations (such as shrinker_debugfs_count_show() and shrinker_debugfs_scan_write()), so there is no need to hold shrinker_rwsem during debugfs operations. Link: https://lkml.kernel.org/r/20230911092517.64141-4-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng Reviewed-by: Muchun Song Cc: Christian Brauner Cc: Christian König Cc: Chuck Lever Cc: Daniel Vetter Cc: Daniel Vetter Cc: Darrick J. Wong Cc: Dave Chinner Cc: Greg Kroah-Hartman Cc: Joel Fernandes Cc: Kirill Tkhai Cc: Paul E. McKenney Cc: Roman Gushchin Cc: Sergey Senozhatsky Cc: Steven Price Cc: Theodore Ts'o Cc: Vlastimil Babka Cc: Abhinav Kumar Cc: Alasdair Kergon Cc: Alexander Viro Cc: Alyssa Rosenzweig Cc: Andreas Dilger Cc: Andreas Gruenbacher Cc: Anna Schumaker Cc: Arnd Bergmann Cc: Bob Peterson Cc: Borislav Petkov Cc: Carlos Llamas Cc: Chandan Babu R Cc: Chao Yu Cc: Chris Mason Cc: Coly Li Cc: Dai Ngo Cc: Dave Hansen Cc: David Airlie Cc: David Hildenbrand Cc: David Sterba Cc: Dmitry Baryshkov Cc: Gao Xiang Cc: Huang Rui Cc: Ingo Molnar Cc: Jaegeuk Kim Cc: Jani Nikula Cc: Jan Kara Cc: Jason Wang Cc: Jeff Layton Cc: Jeffle Xu Cc: Joonas Lahtinen Cc: Josef Bacik Cc: Juergen Gross Cc: Kent Overstreet Cc: Marijn Suijten Cc: "Michael S. Tsirkin" Cc: Mike Snitzer Cc: Minchan Kim Cc: Muchun Song Cc: Nadav Amit Cc: Neil Brown Cc: Oleksandr Tyshchenko Cc: Olga Kornievskaia Cc: Richard Weinberger Cc: Rob Clark Cc: Rob Herring Cc: Rodrigo Vivi Cc: Sean Paul Cc: Song Liu Cc: Stefano Stabellini Cc: Thomas Gleixner Cc: Tomeu Vizoso Cc: Tom Talpey Cc: Trond Myklebust Cc: Tvrtko Ursulin Cc: Xuan Zhuo Cc: Yue Hu Signed-off-by: Andrew Morton Stable-dep-of: b902890c62d2 ("mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()") Signed-off-by: Sasha Levin --- mm/shrinker_debug.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index 3ab53fad8876ea..61702bdc1af48d 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -49,17 +49,12 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) struct mem_cgroup *memcg; unsigned long total; bool memcg_aware; - int ret, nid; + int ret = 0, nid; count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL); if (!count_per_node) return -ENOMEM; - ret = down_read_killable(&shrinker_rwsem); - if (ret) { - kfree(count_per_node); - return ret; - } rcu_read_lock(); memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE; @@ -92,7 +87,6 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); rcu_read_unlock(); - up_read(&shrinker_rwsem); kfree(count_per_node); return ret; @@ -117,7 +111,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, struct mem_cgroup *memcg = NULL; int nid; char kbuf[72]; - ssize_t ret; read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); if (copy_from_user(kbuf, buf, read_len)) @@ -146,12 +139,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, return -EINVAL; } - ret = down_read_killable(&shrinker_rwsem); - if (ret) { - mem_cgroup_put(memcg); - return ret; - } - sc.nid = nid; sc.memcg = memcg; sc.nr_to_scan = nr_to_scan; @@ -159,7 +146,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, shrinker->scan_objects(shrinker, &sc); - up_read(&shrinker_rwsem); mem_cgroup_put(memcg); return size; -- 2.53.0