linux-kernel - What locks are needed to safely use vma->vm

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Date:	Mon, 10 May 2010 21:56:55 -0700 (PDT)
From:	Jose Luis Marchetti <joseluismarchetti@...oo.com.br>
To:	linux-kernel@...r.kernel.org
Subject: What locks are needed to safely use vma->vm_file ?

Hi,

It appears that doing down_read(&mm->mmap_sem) is enough to safely use vma->vm_file, is it correct ?

Also in the lock subject, to get to all vm_files in the system, is the following correct or something is missing ?

read_lock(&tasklist_lock);
for_each_process(p)
{
    mm = get_task_mm(p);
    down_read(&mm->mmap_sem);

    // ... Here what I need to do with this mm vm_file objects

    up_read(&mm->mmap_sem);
    mmput(mm);
}
read_unlock(&tasklist_lock);

Thanks in advance for your answer
José Luís Marchetti

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