linux-kernel - Re: [PATCH] zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF

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Message-ID: <ec203c0e-13a9-4163-94dd-a8a8d6d2c070@kernel.dk>
Date: Wed, 12 Jun 2024 10:57:30 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Oleg Nesterov <oleg@...hat.com>, Andrew Morton
 <akpm@...ux-foundation.org>, Rachel Menge <rachelmenge@...ux.microsoft.com>
Cc: linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
 Wei Fu <fuweid89@...il.com>, apais@...ux.microsoft.com,
 Sudhanva Huruli <Sudhanva.Huruli@...rosoft.com>,
 Christian Brauner <brauner@...nel.org>,
 Mike Christie <michael.christie@...cle.com>,
 Joel Granados <j.granados@...sung.com>, Mateusz Guzik <mjguzik@...il.com>,
 "Paul E. McKenney" <paulmck@...nel.org>,
 Frederic Weisbecker <frederic@...nel.org>,
 Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
 Joel Fernandes <joel@...lfernandes.org>,
 Josh Triplett <josh@...htriplett.org>, Boqun Feng <boqun.feng@...il.com>,
 Steven Rostedt <rostedt@...dmis.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Lai Jiangshan <jiangshanlai@...il.com>, Zqiang <qiang.zhang1211@...il.com>
Subject: Re: [PATCH] zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with
 TIF_SIGPENDING

On 6/8/24 6:06 AM, Oleg Nesterov wrote:
> kernel_wait4() doesn't sleep and returns -EINTR if there is no
> eligible child and signal_pending() is true.
> 
> That is why zap_pid_ns_processes() clears TIF_SIGPENDING but this is not
> enough, it should also clear TIF_NOTIFY_SIGNAL to make signal_pending()
> return false and avoid a busy-wait loop.

Reviewed-by: Jens Axboe <axboe@...nel.dk>

-- 
Jens Axboe