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From: Oleg Nesterov <oleg@redhat.com>
To: Mani Tofigh via B4 Relay <devnull+mt4022.columbia.edu@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	tz2294@columbia.edu, stable@vger.kernel.org,
	Mani Tofigh <mt4022@columbia.edu>
Subject: Re: [PATCH] pipe: keep per-write wakeups for EPOLLEXCLUSIVE consumers
Date: Thu, 12 Nov 2026 00:34:53 +0100	[thread overview]
Message-ID: <avT7nQs7zYseYtMw@redhat.com> (raw)
In-Reply-To: <20261111-pipe-epollexclusive-wakeup-v1-1-0af6283e9fda@columbia.edu>

On 11/11, Mani Tofigh via B4 Relay wrote:
>
> From: Mani Tofigh <mt4022@columbia.edu>
>
> A task blocked in read() on a pipe can sleep while the pipe holds data,
> when an epoll(EPOLLEXCLUSIVE) watcher of the read end was added before
> it.  The watcher's entry on ->rd_wait is exclusive and sits ahead of the
> reader, so a write into an empty pipe wakes only the watcher.

I am already sleeping, but at first glance this is already wrong?

I mean, a WQ_FLAG_EXCLUSIVE waiter should not sit ahead of non-exclusive
waiter, no?

Oleg.


  reply	other threads:[~2026-11-11 23:35 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-11 21:02 [PATCH] pipe: keep per-write wakeups for EPOLLEXCLUSIVE consumers Mani Tofigh via B4 Relay
2026-11-11 21:02 ` Mani Tofigh
2026-11-11 23:34 ` Oleg Nesterov [this message]
2026-11-12 10:26   ` Oleg Nesterov
2026-11-12 12:56 ` Oleg Nesterov

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