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Subject: Re: [PATCH v7 3.2-rc2 9/30] uprobes: Background page replacement.
From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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        Anton Arapov <anton@redhat.com>,
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Date: Fri, 25 Nov 2011 15:29:24 +0100
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On Fri, 2011-11-18 at 16:38 +0530, Srikar Dronamraju wrote:
> +       /* poke the new insn in, ASSUMES we don't cross page boundary */
> +       vaddr &= ~PAGE_MASK;
> +       memcpy(vaddr_new + vaddr, &opcode, uprobe_opcode_sz);

I still don't get why you don't simply write something like:

BUG_ON(vaddr + uprobe_opcode_size >= PAGE_SIZE);

That's as descriptive as the comment and actually does something if
someone got it wrong, instead of silently corrupting crap.