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Date:   Tue, 24 Aug 2021 19:35:27 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Dave Jones <davej@codemonkey.org.uk>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: 5.14-rc breaks iotop swap io monitoring.
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On Tue, Aug 24, 2021 at 09:34:02AM -0700, Linus Torvalds wrote:

> Even if you enable it at run-time, processes that have been started
> before it was enabled won't actually have the 'tsk->delays'
> allocation. So I'm not sure how effective the run-time thing is.

Right; we *could* fix that by looping through the tasklist; grabbing a
task ref, doing the alloc and restarting until we've iterated the whole
tasklist and not found a task without a delays thing.

Didn't think it would be worth it, but can be done..