From: kanoj@google.engr.sgi.com (Kanoj Sarcar)
To: Jakub Jelinek <jakub@redhat.com>
Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org, davem@redhat.com
Subject: Re: 2.3 Pagedir allocation/free and update races
Date: Tue, 14 Dec 1999 15:00:19 -0800 (PST) [thread overview]
Message-ID: <199912142300.PAA05447@google.engr.sgi.com> (raw)
In-Reply-To: <19991214111351.U822@mff.cuni.cz> from "Jakub Jelinek" at Dec 14, 99 11:13:51 am
>
> On Tue, Dec 14, 1999 at 01:46:00AM -0800, Kanoj Sarcar wrote:
> > This note describes races in the procedures that allocate and free
> > user level page directories. Platform code maintainers, please
> > read.
>
> pgd_alloc/free are never invoked from interrupts and the kernel code is not
> preemptive, so per-CPU caches are safe, aren't they?
>
> Cheers,
> Jakub
Yes, I am sorry for the misleading logic in my note. Per-cpu caches are
safe (I wonder why it was taken out for i386). For architectures that
have to do set_pgdir() though, the pgdir update code might be racy,
unless the arch code has locks to protect the page directory scanning.
Btw, Linus indicated to me he ran into problems with the patch, and
will be pulling it out in the next pre-release. I will take a closer look
at the code.
Kanoj
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next prev parent reply other threads:[~1999-12-14 23:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-12-14 9:46 Kanoj Sarcar
1999-12-14 9:55 ` David S. Miller
1999-12-14 10:13 ` Jakub Jelinek
1999-12-14 23:00 ` Kanoj Sarcar [this message]
1999-12-14 23:08 ` David S. Miller
1999-12-14 23:51 ` Kanoj Sarcar
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