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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: syzbot <syzbot+ecccecbc636b455f9084@syzkaller.appspotmail.com>,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com, tj@kernel.org,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] kernfs: Drop kernfs_rwsem while invoking
 lookup_positive_unlocked().
Message-ID: <20250221074957.6Gqax5ib@linutronix.de>
References: <67b45276.050a0220.173698.004f.GAE@google.com>
 <20250218163938.xmvjlJ0K@linutronix.de>
 <20250220203924.GL1977892@ZenIV>
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In-Reply-To: <20250220203924.GL1977892@ZenIV>

On 2025-02-20 20:39:24 [+0000], Al Viro wrote:
> On Tue, Feb 18, 2025 at 05:39:38PM +0100, Sebastian Andrzej Siewior wrote:
> 
> > +	scoped_guard(rcu) {
> > +		knparent = find_next_ancestor(kn, NULL);
> > +		if (WARN_ON(!knparent)) {
> > +			dput(dentry);
> > +			return ERR_PTR(-EINVAL);
> > +		}
> 
> NAK.  dput() is blocking; you *can't* do that under rcu_read_lock().

Thank you.
Since it got merged, let me do another one on top.

Sebastian