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SubjectRe: [RFC PATCH 5/5] refresh VM committed space after a task migration
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On Tue, 2008-06-10 at 01:33 +0200, Andrea Righi wrote:
> + preempt_disable();
> + committed = atomic_long_read(&p->vm_committed_space);
> + atomic_long_sub(committed, &old_mem->vmacct.vm_committed_space);
> + atomic_long_add(committed, &mem->vmacct.vm_committed_space);
> + preempt_enable();
> out:
> mmput(mm);
> }

Why bother with the preempt stuff here? What does the actually protect
against? I assume that you're trying to keep other tasks that might run
on this CPU from seeing weird, inconsistent numbers in here. Is there
some other looks that keeps *other* cpus from seeing this?

In any case, I think it needs a big, fat comment.

-- Dave



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