From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794062759; b=ktwrUZjNT7pGUm61Q0wAwobTJ87S7xfpyx9wBSkWbdmoQZhW/AitkjM7Pob5/OsR9cCK EfnGOX6u55jnNS2WrSTWlm6+fyrPtEvitweC9Y0u/yXUBUJC8xkQHAstEOVnI1lE/n+5m pAuZAUnUBueCU6XtgZKEyT/DYOQ7U2YE7HW80i5ZDG5eCparseqDrTmn42wU1FSxg3QEm 90TIN5M87hLTtjTaA4YzVfGzcczh8AZ4olF1gahl7klC0TuDqbTVublPLMboekJ+9URyY fQ3ikSIL/FeLLC+Tmly3dHbOMG21ENwb27l04Wuta5g6vuZJyIB4G/VA+IP83FMliCw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794062759; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=HJ5/ylU/bAUBZO9xRPdBTBLjpUndXiOXryoxPdtEFN4=; b=lamUKzbSu0hvwkKYI+//z00BasP1p8pGNpgqotbOHfF6OWOsf2f4YORb9wFdz31bqkH4 LHlwIHKqaoJpumudSZ+bDLalVP2H/o7bIJCPSJITQ12C/g6TuFgqJ+GXbInDwMoWLO7HP sNef0n4GxVt8DGcfwiGXklVPkqzAz68hNQD/kshuLu+4u9TrboxANhKpvRuKtdxClq6xo khe9xHhcI0MWtGYy3LeLBT5N0BUShfvbXhsujocxpkfd9R/7GVV2VFmf7+uu9AB4XZYiZ vaWDbcitgerqvERS8p9INtSWcBhuDUhB47bxQ2Hmq2tul+c4p87RXljEiC/bAcU9I9w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ALTotvpl; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1008606A32D; Sat, 7 Nov 2026 14:45:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ALTotvpl Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DD761F008A1; Sat, 7 Nov 2026 14:45:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794062759; bh=HJ5/ylU/bAUBZO9xRPdBTBLjpUndXiOXryoxPdtEFN4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ALTotvplTxf/wrhCaz7qDJsCu9o+NLzbaQXBoI65W6j4pjDVJasp+8nZbakPzmBte Lv/Pew5mrmcdYkNKtta6et+Za9g6+x+Yui2i3WQ84JGADsZtsdbV9pxeTRrktVoFVS XFYJu7o1rZUw4CH1y1sRq8Jp4j561F1sERGWTRiQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Jan Kara , "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.18 070/869] fs_pin: publish pins with RCU list helpers Date: Sat, 7 Nov 2026 08:45:52 -0500 Message-ID: <20261107134854.880636088@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Karl Mehltretter [ Upstream commit 8d01d6b4c17c406f37a9b6edac93dfb858af30d0 ] pin_insert() initializes a pin before adding it under pin_lock. The kill paths read the list heads under RCU without taking that lock. Plain hlist insertion does not publish the earlier initialization to those readers. KCSAN weak-memory checking reported acct_on() callback initialization racing with pin_kill() after the superblock-list publication. The corresponding LKMM model permits the stale read with plain publication; the RCU release/acquire pair forbids it. Use the RCU hlist add and dereference helpers for both pin lists. Fixes: 2798d4ce6160 ("acct: get rid of acct_lock for acct->count") Cc: stable@vger.kernel.org Signed-off-by: Karl Mehltretter Link: https://patch.msgid.link/20260903002100.34822-1-kmehltretter@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin --- fs/fs_pin.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/fs_pin.c b/fs/fs_pin.c index 47ef3c71ce907..1a508f2167e0a 100644 --- a/fs/fs_pin.c +++ b/fs/fs_pin.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include #include "internal.h" @@ -22,8 +23,8 @@ void pin_remove(struct fs_pin *pin) void pin_insert(struct fs_pin *pin, struct vfsmount *m) { spin_lock(&pin_lock); - hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins); - hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins); + hlist_add_head_rcu(&pin->s_list, &m->mnt_sb->s_pins); + hlist_add_head_rcu(&pin->m_list, &real_mount(m)->mnt_pins); spin_unlock(&pin_lock); } @@ -73,7 +74,7 @@ void mnt_pin_kill(struct mount *m) while (1) { struct hlist_node *p; rcu_read_lock(); - p = READ_ONCE(m->mnt_pins.first); + p = rcu_dereference(hlist_first_rcu(&m->mnt_pins)); if (!p) { rcu_read_unlock(); break; @@ -87,7 +88,7 @@ void group_pin_kill(struct hlist_head *p) while (1) { struct hlist_node *q; rcu_read_lock(); - q = READ_ONCE(p->first); + q = rcu_dereference(hlist_first_rcu(p)); if (!q) { rcu_read_unlock(); break; -- 2.53.0