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To: linux-kernel@vger.kernel.org
From: torvalds@transmeta.com (Linus Torvalds)
Subject: Re: BUG: Global FPU corruption in 2.2
Date: 24 Apr 2001 09:10:07 -0700
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In article <20010423161148.6465.qmail@theseus.mathematik.uni-ulm.de>,
Christian Ehrhardt <ehrhardt@mathematik.uni-ulm.de> wrote:
>
>1.) If I'm not mistaken switch_to changes current->flags without
>atomic operations and without any locks and sys_ptrace changes
>child->flags only protected by the big kernel lock.

ptrace only operates on processes that are stopped. So there are no
locking issues - we've synchronized on a much higher level than a
spinlock or semaphore.

That said, it does look like 2.2.x has a real bug, and maybe the ptrace
task stopping sycnhronization is broken..

		Linus
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