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Thu, 01 Oct 2026 23:01:32 -0700 (PDT) Date: Fri, 2 Oct 2026 15:01:30 +0900 From: Hyunchul Lee To: NeilBrown Cc: Miklos Szeredi , Amir Goldstein , Kees Cook , Joel Granados , Richard Weinberger , Anton Ivanov , Johannes Berg , Breno Leitao , Andreas Hindborg , Jan Harkes , Hugh Dickins , Baolin Wang , Namjae Jeon , Carlos Maiolino , Alexander Viro , Christian Brauner , Jeff Layton , Jan Kara , linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-um@lists.infradead.org, codalist@coda.cs.cmu.edu, coda@cs.cmu.edu, linux-mm@kvack.org, ntfs@lists.linux.dev, linux-xfs@vger.kernel.org Subject: Re: [PATCH 1/7] VFS/xfs/ntfs: drop parent lock across d_alloc_parallel() in d_add_ci() Message-ID: References: <20260929034158.1455429-1-neilb@ownmail.net> <20260929034158.1455429-2-neilb@ownmail.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260929034158.1455429-2-neilb@ownmail.net> X-Rspam-User: X-Stat-Signature: tgfj5gnu5su4usyr4pmyufrkzrmej15i X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: DD83C180008 X-HE-Tag: 1790920894-491734 X-HE-Meta: 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 QUkaxfyF 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 29, 2026 at 01:36:01PM +1000, NeilBrown wrote: > From: NeilBrown > > A proposed change will invert the lock ordering between > d_alloc_parallel() and inode_lock() on the parent. > When that happens it will not be safe to call d_alloc_parallel() while > holding the parent lock - even shared. > > We don't need to keep the parent lock held when d_add_ci() is run - the > VFS doesn't need it as dentry is exclusively held due to > DCACHE_PAR_LOOKUP and the filesystem has finished its work. > > So drop and reclaim the lock (shared or exclusive as determined by > LOOKUP_SHARED) to avoid future deadlock. > > Signed-off-by: NeilBrown For the NTFS part, Looks good to me. Reviewed-by: Hyunchul Lee -- Thanks, Hyunchul