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From: Andrew Morton <akpm@linux-foundation.org>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Michal Hocko <mhocko@suse.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH] proc/kpageflags: add KPF_WAITERS
Date: Fri, 16 Feb 2018 15:57:52 -0800	[thread overview]
Message-ID: <20180216155752.4a17cfd41875911c79807585@linux-foundation.org> (raw)
In-Reply-To: <151834540184.176427.12174649162560874101.stgit@buzz>

On Sun, 11 Feb 2018 13:36:41 +0300 Konstantin Khlebnikov <khlebnikov@yandex-team.ru> wrote:

> KPF_WAITERS indicates tasks are waiting for a page lock or writeback.
> This might be false-positive, in this case next unlock will clear it.

Well, kpageflags is full of potential false-positives.  Or do you think
this flag is especially vulnerable?

In other words, under what circumstances will we have KPF_WAITERS set
when PG_locked and PG-writeback are clear?

> This looks like worth information not only for kernel hacking.

Why?  What are the use-cases, in detail?  How are we to justify this
modification?

> In tool page-types in non-raw mode treat KPF_WAITERS without
> KPF_LOCKED and KPF_WRITEBACK as false-positive and hide it.

>  fs/proc/page.c                         |    1 +
>  include/uapi/linux/kernel-page-flags.h |    1 +
>  tools/vm/page-types.c                  |    7 +++++++

Please update Documentation/vm/pagemap.txt.

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  reply	other threads:[~2018-02-16 23:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-11 10:36 Konstantin Khlebnikov
2018-02-16 23:57 ` Andrew Morton [this message]
2018-02-17  8:14   ` Konstantin Khlebnikov
2018-02-21  0:00     ` Andrew Morton
2018-02-17  8:15 ` [PATCH] Documentation/vm/pagemap.txt: document bit WAITERS Konstantin Khlebnikov

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