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Date:   Sat, 19 Aug 2023 04:53:03 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Hongchen Zhang <zhanghongchen@loongson.cn>
Cc:     David Howells <dhowells@redhat.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Steve French <stfrench@microsoft.com>,
        Jens Axboe <axboe@kernel.dk>, David Disseldorp <ddiss@suse.de>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Nick Alcock <nick.alcock@oracle.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        loongson-kernel@lists.loongnix.cn
Subject: Re: [PATCH v5 2/2] pipe: use __pipe_{lock,unlock} instead of spinlock
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References: <20230811010309.20196-2-zhanghongchen@loongson.cn>
 <20230811010309.20196-1-zhanghongchen@loongson.cn>
 <3955287.1692002820@warthog.procyon.org.uk>
 <b6f395a6-ca81-f107-0a3f-59e8f8d41f9d@loongson.cn>
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On Sat, Aug 19, 2023 at 11:28:58AM +0800, Hongchen Zhang wrote:
> Hi David,
> 
> On 2023/8/14 pm 4:47, David Howells wrote:
> > Hongchen Zhang <zhanghongchen@loongson.cn> wrote:
> > 
> > > -	spin_lock_irq(&pipe->rd_wait.lock);
> > > +	__pipe_lock(pipe);
> > 
> I changed the code and the post_one_notification is not called inside spin
> lock ,please check this patch again.

In remove_watch_from_object(), you moved post_one_notification() before
lock_queue(), but it's still called inside a RCU read-side critical
section, which cannot sleep.

Please test with CONFIG_DEBUG_ATOMIC_SLEEP before you send a new version.
You should probably turn on DEBUG_SPINLOCK, LOCKDEP, DEBUG_MUTEXES
and a few other debug options.