From: Kees Cook <keescook@chromium.org>
To: Mateusz Guzik <mjguzik@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>,
Eric Biederman <ebiederm@xmission.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fs/exec.c: Add fast path for ENOENT on PATH search before allocating mm
Date: Tue, 7 Nov 2023 14:50:01 -0800 [thread overview]
Message-ID: <202311071445.53E5D72C@keescook> (raw)
In-Reply-To: <CAGudoHFsqMPmVvaV7BebGkpkw=pSQY8PLdB-1S3W5NpYh6trmA@mail.gmail.com>
On Tue, Nov 07, 2023 at 10:23:16PM +0100, Mateusz Guzik wrote:
> If the patch which dodges second lookup still somehow appears slower a
> flamegraph or other profile would be nice. I can volunteer to take a
> look at what's going on provided above measurements will be done and
> show funkyness.
When I looked at this last, it seemed like all the work done in
do_filp_open() (my patch, which moved the lookup earlier) was heavier
than the duplicate filename_lookup().
What I didn't test was moving the sched_exec() before the mm creation,
which Peter confirmed shouldn't be a problem, but I think that might be
only a tiny benefit, if at all.
If you can do some comparisons, that would be great; it always takes me
a fair bit of time to get set up for flame graph generation, etc. :)
-Kees
--
Kees Cook
next prev parent reply other threads:[~2023-11-07 22:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 13:41 [PATCH] fs/exec.c: Add fast path for ENOENT on PATH search before allocating mm Josh Triplett
2022-09-16 14:38 ` Kees Cook
2022-09-16 20:13 ` Josh Triplett
2022-09-17 0:11 ` Kees Cook
2022-09-17 0:50 ` Josh Triplett
2022-09-19 20:02 ` Kees Cook
2022-10-01 16:01 ` Josh Triplett
2022-09-19 14:34 ` Peter Zijlstra
2022-09-22 7:27 ` [fs/exec.c] 0a276ae2d2: BUG:workqueue_lockup-pool kernel test robot
2023-11-07 20:30 ` [PATCH] fs/exec.c: Add fast path for ENOENT on PATH search before allocating mm Kees Cook
2023-11-07 20:51 ` Mateusz Guzik
2023-11-07 21:23 ` Mateusz Guzik
2023-11-07 22:50 ` Kees Cook [this message]
2023-11-07 23:08 ` Mateusz Guzik
2023-11-07 23:39 ` Kees Cook
2023-11-08 0:03 ` Mateusz Guzik
2023-11-08 19:25 ` Kees Cook
2023-11-08 19:31 ` Kees Cook
2023-11-08 19:35 ` Mateusz Guzik
2023-11-09 0:17 ` Eric W. Biederman
2023-11-09 12:21 ` Mateusz Guzik
2023-11-10 5:26 ` Eric W. Biederman
2023-11-07 20:37 ` Kees Cook
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