From: Michel Lespinasse <walken@google.com>
To: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Waychison <mikew@google.com>,
Suleiman Souhlal <suleiman@google.com>,
Ying Han <yinghan@google.com>
Subject: Re: [PATCH 10/10] Use down_read_critical() for /sys/<pid>/exe and /sys/<pid>/maps files
Date: Thu, 20 May 2010 19:44:12 -0700 [thread overview]
Message-ID: <AANLkTimcqi9TUnWMOIRAYA-SphHzqXeb9s_B54eNnkT4@mail.gmail.com> (raw)
In-Reply-To: <31783.1274282492@redhat.com>
On Wed, May 19, 2010 at 8:21 AM, David Howells <dhowells@redhat.com> wrote:
> 0 0 10 2 1 s 2/2 0 0 2217200 636227 210255
> 0 0 10 2 1 s 2/2 0 0 2217903 629175 212926
> 0 0 10 2 1 s 2/2 0 0 2224136 647912 212506
>
> Feel free to have a play.
Thanks for sharing your testing code.
> BTW, the code also works on FRV in NOMMU mode (which uses the spinlock-based
> rwsem version).
Yes, I made sure to keep the generic (and non-x86 asm) versions
working by always separating x86 specific changes from the rest.
> However... I'm not certain that giving a process that's accessing
> /proc/pid/maps priority over a second process that may be trying to do mmap or
> page fault or something internally is a good idea.
One thing to keep in mind if you're concerned about the higher
priority is that these /proc files are still not open to everyone - a
user can't read the /proc/<pid>/exe and /proc/<pid>/maps files for
another user's processes unless he's got CAP_SYS_PTRACE priviledges.
--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
next prev parent reply other threads:[~2010-05-21 2:44 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-17 22:25 [PATCH 00/10] V3: rwsem changes + down_read_critical() proposal Michel Lespinasse
2010-05-17 22:25 ` [PATCH 01/10] x86 rwsem: minor cleanups Michel Lespinasse
2010-05-17 22:25 ` [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers Michel Lespinasse
2010-05-17 22:25 ` [PATCH 03/10] rwsem: lighter active count checks when waking up readers Michel Lespinasse
2010-05-17 22:25 ` [PATCH 04/10] rwsem: let RWSEM_WAITING_BIAS represent any number of waiting threads Michel Lespinasse
2010-05-17 22:25 ` [PATCH 05/10] rwsem: wake queued readers when writer blocks on active read lock Michel Lespinasse
2010-05-17 22:25 ` [PATCH 06/10] rwsem: smaller wrappers around rwsem_down_failed_common Michel Lespinasse
2010-05-17 22:25 ` [PATCH 07/10] generic rwsem: implement down_read_critical() / up_read_critical() Michel Lespinasse
2010-05-17 22:44 ` Linus Torvalds
2010-05-17 23:13 ` Michel Lespinasse
2010-05-17 23:20 ` Michel Lespinasse
2010-05-19 13:21 ` David Howells
2010-05-19 23:47 ` Michel Lespinasse
2010-05-21 3:35 ` Michel Lespinasse
2010-05-17 22:25 ` [PATCH 08/10] rwsem: down_read_critical infrastructure support Michel Lespinasse
2010-05-17 22:25 ` [PATCH 09/10] x86 rwsem: down_read_critical implementation Michel Lespinasse
2010-05-17 22:25 ` [PATCH 10/10] Use down_read_critical() for /sys/<pid>/exe and /sys/<pid>/maps files Michel Lespinasse
2010-05-19 11:47 ` [PATCH 01/10] x86 rwsem: minor cleanups David Howells
2010-05-20 21:37 ` Michel Lespinasse
2010-05-19 12:04 ` [PATCH 02/10] rwsem: fully separate code pathes to wake writers vs readers David Howells
2010-05-20 21:48 ` Michel Lespinasse
2010-05-19 12:25 ` [PATCH 03/10] rwsem: lighter active count checks when waking up readers David Howells
2010-05-20 22:33 ` Michel Lespinasse
2010-05-21 8:06 ` David Howells
2010-05-19 12:33 ` [PATCH 04/10] rwsem: let RWSEM_WAITING_BIAS represent any number of waiting threads David Howells
2010-05-19 12:44 ` [PATCH 05/10] rwsem: wake queued readers when writer blocks on active read lock David Howells
2010-05-19 12:51 ` [PATCH 06/10] rwsem: smaller wrappers around rwsem_down_failed_common David Howells
2010-05-19 13:34 ` [PATCH 08/10] rwsem: down_read_critical infrastructure support David Howells
2010-05-20 23:30 ` Michel Lespinasse
2010-05-21 8:03 ` David Howells
2010-05-19 14:36 ` [PATCH 09/10] x86 rwsem: down_read_critical implementation David Howells
2010-05-19 15:21 ` [PATCH 10/10] Use down_read_critical() for /sys/<pid>/exe and /sys/<pid>/maps files David Howells
2010-05-21 2:44 ` Michel Lespinasse [this message]
2010-05-22 1:49 ` Michel Lespinasse
2010-05-25 9:42 ` David Howells
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