From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 023792E2EEF for ; Mon, 20 Oct 2025 07:57:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760947078; cv=none; b=sbYsA44iDrulCi+zmDQaRoDjtLOx572FvSPdIYtUPO+PJ6o0thHFFoH8Mt04Kmg4bRMwrupz+R8qI0ZMc8QpQ/qP24+Uurh5FJXhwge+lX7YfXg+rb3cg3Aq/hc8PZWWAiYVTSkqFW8gGL8rcPoUi+toLkW5iAq7luxTDBB/FJo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760947078; c=relaxed/simple; bh=8zBaeTAGRid/xfdpIBpVoSaALQ/grLexOcPr4gVnjmc=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=qHEZ9IuqBVyRVopkhvYdnVrYuE6uxhZGV0YlCCxGUDrZFDyxrMOeu4jowdC64/N40n/fjORxOh3pr2WUM+uXmQ2UBvpmK2KxlSyZYdsiE32VUaTvJ0uLBHvZAeWK6pacML+D1NfEikOFAzXaie8avabGYPi/AU86Nd8OTflsTbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=g6TO3KLM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="g6TO3KLM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3567DC4CEF9; Mon, 20 Oct 2025 07:57:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760947077; bh=8zBaeTAGRid/xfdpIBpVoSaALQ/grLexOcPr4gVnjmc=; h=Subject:To:Cc:From:Date:From; b=g6TO3KLMDPBXz1uy5lBu1/PBsyrE7aflZIahQSL6suvmK8K9z4v7d5VDgnO4qDPVA Cl286az+ztaURtniL3OiYTs3uIR5ZVjVVb6omfC6xXpI//cahzgiHedZI4oUGT1WY9 zV1UcMG/Im5YPqzXVNsz9Hu3TeTu38g3qHwUbzug= Subject: FAILED: patch "[PATCH] vfs: Don't leak disconnected dentries on umount" failed to apply to 5.4-stable tree To: jack@suse.cz,brauner@kernel.org Cc: From: Date: Mon, 20 Oct 2025 09:57:42 +0200 Message-ID: <2025102042-tactical-subtract-5775@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=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 56094ad3eaa21e6621396cc33811d8f72847a834 # git commit -s git send-email --to '' --in-reply-to '2025102042-tactical-subtract-5775@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 56094ad3eaa21e6621396cc33811d8f72847a834 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 2 Oct 2025 17:55:07 +0200 Subject: [PATCH] vfs: Don't leak disconnected dentries on umount When user calls open_by_handle_at() on some inode that is not cached, we will create disconnected dentry for it. If such dentry is a directory, exportfs_decode_fh_raw() will then try to connect this dentry to the dentry tree through reconnect_path(). It may happen for various reasons (such as corrupted fs or race with rename) that the call to lookup_one_unlocked() in reconnect_one() will fail to find the dentry we are trying to reconnect and instead create a new dentry under the parent. Now this dentry will not be marked as disconnected although the parent still may well be disconnected (at least in case this inconsistency happened because the fs is corrupted and .. doesn't point to the real parent directory). This creates inconsistency in disconnected flags but AFAICS it was mostly harmless. At least until commit f1ee616214cb ("VFS: don't keep disconnected dentries on d_anon") which removed adding of most disconnected dentries to sb->s_anon list. Thus after this commit cleanup of disconnected dentries implicitely relies on the fact that dput() will immediately reclaim such dentries. However when some leaf dentry isn't marked as disconnected, as in the scenario described above, the reclaim doesn't happen and the dentries are "leaked". Memory reclaim can eventually reclaim them but otherwise they stay in memory and if umount comes first, we hit infamous "Busy inodes after unmount" bug. Make sure all dentries created under a disconnected parent are marked as disconnected as well. Reported-by: syzbot+1d79ebe5383fc016cf07@syzkaller.appspotmail.com Fixes: f1ee616214cb ("VFS: don't keep disconnected dentries on d_anon") CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Christian Brauner diff --git a/fs/dcache.c b/fs/dcache.c index a067fa0a965a..035cccbc9276 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2557,6 +2557,8 @@ struct dentry *d_alloc_parallel(struct dentry *parent, spin_lock(&parent->d_lock); new->d_parent = dget_dlock(parent); hlist_add_head(&new->d_sib, &parent->d_children); + if (parent->d_flags & DCACHE_DISCONNECTED) + new->d_flags |= DCACHE_DISCONNECTED; spin_unlock(&parent->d_lock); retry: