From: Daniel Colascione <dancol@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Tim Murray <timmurray@google.com>,
Joel Fernandes <joelaf@google.com>,
Suren Baghdasaryan <surenb@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <guro@fb.com>, Vlastimil Babka <vbabka@suse.cz>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Dennis Zhou (Facebook)" <dennisszhou@gmail.com>,
Prashant Dhamdhere <pdhamdhe@redhat.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v2] Document /proc/pid PID reuse behavior
Date: Wed, 7 Nov 2018 10:21:59 -0800 [thread overview]
Message-ID: <CAKOZuet9KGHc9dAyC=-cMZNt39s2m9=YEu3R1-7ExWzaNzLzjA@mail.gmail.com> (raw)
In-Reply-To: <20181107171644.GK3074@bombadil.infradead.org>
On Wed, Nov 7, 2018 at 9:16 AM, Matthew Wilcox <willy@infradead.org> wrote:
> On Tue, Nov 06, 2018 at 08:01:13AM +0200, Mike Rapoport wrote:
>> > diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
>> > index 12a5e6e693b6..0b14460f721d 100644
>> > --- a/Documentation/filesystems/proc.txt
>> > +++ b/Documentation/filesystems/proc.txt
>> > @@ -125,6 +125,13 @@ process running on the system, which is named after the process ID (PID).
>> > The link self points to the process reading the file system. Each process
>> > subdirectory has the entries listed in Table 1-1.
>> >
>> > +Note that an open a file descriptor to /proc/<pid> or to any of its
>
> "open file descriptor" (the "a" is unnecessary)
Thanks for spotting that. I had to re-read that sentence three times
or so before even seeing that extra "a".
>> > +contained files or subdirectories does not prevent <pid> being reused
>> > +for some other process in the event that <pid> exits. Operations on
>> > +open /proc/<pid> file descriptors corresponding to dead processes
>> > +never act on any new process that the kernel may, through chance, have
>> > +also assigned the process ID <pid>. Instead, operations on these FDs
>> > +usually fail with ESRCH.
>
> The paragraph is a bit wordy. More pithy:
>
> An open file descriptor for /proc/<pid> (or any of the files or
> subdirectories in it) does not prevent <pid> from being reused after
> the process exits. Operations on a file descriptor referring to a dead
> process usually return ESRCH. They do not act on any new process which
> has been assigned the same <pid>.
I'll send a new patch version --- unless we can just tweak the patch
when we merge it into the tree?
next prev parent reply other threads:[~2018-11-07 18:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 15:06 [PATCH] Document /proc/pid PID reuse behavior Daniel Colascione
2018-11-01 7:08 ` Mike Rapoport
2018-11-05 13:22 ` [PATCH v2] " Daniel Colascione
2018-11-06 6:01 ` Mike Rapoport
2018-11-07 17:16 ` Matthew Wilcox
2018-11-07 18:21 ` Daniel Colascione [this message]
2018-11-06 13:05 ` Michal Hocko
2018-11-07 15:48 ` Daniel Colascione
2018-11-07 16:00 ` Michal Hocko
2018-11-07 16:10 ` Daniel Colascione
2018-11-07 16:19 ` Michal Hocko
2018-11-19 11:16 ` Aleksa Sarai
2018-11-07 17:04 ` Martin Steigerwald
2018-11-08 12:02 ` David Laight
2018-11-08 12:27 ` Matthew Wilcox
2018-11-08 13:42 ` David Laight
2018-11-08 14:07 ` Matthew Wilcox
2018-11-08 14:14 ` David Laight
2018-11-08 13:25 ` Michal Hocko
2018-11-19 10:54 ` Pavel Machek
2018-11-19 16:24 ` Daniel Colascione
2018-11-20 8:50 ` Pavel Machek
2018-11-20 9:05 ` Vlastimil Babka
2018-11-20 9:18 ` Pavel Machek
2018-11-20 17:39 ` Matthew Wilcox
2018-11-20 17:48 ` Daniel Colascione
2018-11-20 17:59 ` Matthew Wilcox
2018-11-20 16:37 ` Joel Fernandes
2018-11-20 16:49 ` Jonathan Corbet
2018-11-20 16:57 ` Pavel Machek
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