From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>,
linuxppc-dev list <linuxppc-dev@ozlabs.org>,
Paul Mackerras <paulus@samba.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] powerpc vdso updates
Date: Tue, 30 May 2006 17:21:40 +1000 [thread overview]
Message-ID: <1148973700.15722.34.camel@localhost.localdomain> (raw)
In-Reply-To: <20060530062447.GD19870@elte.hu>
> get_unmapped_area() without holding the mmap semaphore seems dangerous.
> The VDSO setup itself should be 'private' to the process, but i'm not
> totally sure that no other kernel code could get access to this mm. For
> example the swapout code? Am i missing something?
Well, all of this happens so early, I doubt anything will cause actual
harm, for get_unmapped_area to be a problem, something would have to
concurrently allocate a VMA (or dispose of) I think that can't happen at
this point before we even run the binary but yes, better safe than
sorry... I supose the whole patch could get in 2.6.17 even without the
arch_vma_name (that is it can be there, it wont be used though until
your patch gets in).
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] powerpc vdso updates
Date: Tue, 30 May 2006 17:21:40 +1000 [thread overview]
Message-ID: <1148973700.15722.34.camel@localhost.localdomain> (raw)
In-Reply-To: <20060530062447.GD19870@elte.hu>
> get_unmapped_area() without holding the mmap semaphore seems dangerous.
> The VDSO setup itself should be 'private' to the process, but i'm not
> totally sure that no other kernel code could get access to this mm. For
> example the swapout code? Am i missing something?
Well, all of this happens so early, I doubt anything will cause actual
harm, for get_unmapped_area to be a problem, something would have to
concurrently allocate a VMA (or dispose of) I think that can't happen at
this point before we even run the binary but yes, better safe than
sorry... I supose the whole patch could get in 2.6.17 even without the
arch_vma_name (that is it can be there, it wont be used though until
your patch gets in).
Ben.
next prev parent reply other threads:[~2006-05-30 7:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-30 3:51 [PATCH] powerpc vdso updates Benjamin Herrenschmidt
2006-05-30 3:51 ` Benjamin Herrenschmidt
2006-05-30 6:24 ` Ingo Molnar
2006-05-30 6:24 ` Ingo Molnar
2006-05-30 7:21 ` Benjamin Herrenschmidt [this message]
2006-05-30 7:21 ` Benjamin Herrenschmidt
2006-06-10 3:15 ` Anton Blanchard
2006-06-10 6:30 ` Benjamin Herrenschmidt
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