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From: Vlastimil Babka <vbabka@suse.cz>
To: Daniel Colascione <dancol@google.com>
Cc: Thomas Lindroth <thomas.lindroth@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [REGRESSION] "Locked" and "Pss" in /proc/*/smaps are the same
Date: Wed, 4 Jul 2018 10:46:52 +0200	[thread overview]
Message-ID: <f31b26d0-b94e-b545-8776-a4494179149d@suse.cz> (raw)
In-Reply-To: <CAKOZuev9K0EMpqBoie4H7XduB63KayORxO=JEZvS9rv_4PVsqQ@mail.gmail.com>

On 07/03/2018 06:20 PM, Daniel Colascione wrote:
> On Tue, Jul 3, 2018 at 12:36 AM, Vlastimil Babka <vbabka@suse.cz> wrote:
>> +CC
>>
>> On 07/01/2018 08:31 PM, Thomas Lindroth wrote:
>>> While looking around in /proc on my v4.14.52 system I noticed that
>>> all processes got a lot of "Locked" memory in /proc/*/smaps. A lot
>>> more memory than a regular user can usually lock with mlock().
>>>
>>> commit 493b0e9d945fa9dfe96be93ae41b4ca4b6fdb317 (v4.14-rc1) seems
>>> to have changed the behavior of "Locked".
> 
> Thanks for fixing that. I submitted a patch [1] for this bug and some
> others a while ago, but the patch didn't make it into the tree because
> or wasn't split up correctly or something, and I had to do other work.

Hmm I see. I pondered about the patch and wondered if the scenarios it
fixes are really possible for smaps_rollup. Did you observe them in
practice? Namely:
- when seq_file starts and stops multiple times on a single open file
description
- when it issues multiple show calls for the same iterator value

I don't think it can happen when all positions but the last one just
return SEQ_SKIP.

Anyway I think the seq_file iterator API usage for smaps_rollup is
unnecessary. Semantically the file shows only one "element" and that's
the set of rollup values for all vmas. Letting seq_file do the iteration
over vmas brings only complications?

> [1] https://marc.info/?l=linux-mm&m=151927723128134&w=2
> 

      reply	other threads:[~2018-07-04  8:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-01 18:31 [REGRESSION] "Locked" and "Pss" in /proc/*/smaps are the same Thomas Lindroth
2018-07-03  7:36 ` Vlastimil Babka
2018-07-03  7:45   ` Vlastimil Babka
2018-07-03 16:20   ` Daniel Colascione
2018-07-04  8:46     ` Vlastimil Babka [this message]

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