Re: [PATCH] [13/16] POISON: The high level memory error handler in the VM

Johannes Weiner
2009-04-07T18:52:22Z

Hi Andi,

On Tue, Apr 07, 2009 at 05:10:10PM +0200, Andi Kleen wrote:

> +static void collect_procs_anon(struct page *page, struct list_head *to_kill,
> + struct to_kill **tkc)
> +{
> + struct vm_area_struct *vma;
> + struct task_struct *tsk;
> + struct anon_vma *av = page_lock_anon_vma(page);
> +
> + if (av == NULL) /* Not actually mapped anymore */
> + goto out;
> +
> + read_lock(&tasklist_lock);
> + for_each_process (tsk) {
> + if (!tsk->mm)
> + continue;
> + list_for_each_entry (vma, &av->head, anon_vma_node) {
> + if (vma->vm_mm == tsk->mm)
> + add_to_kill(tsk, page, vma, to_kill, tkc);
> + }
> + }
> + read_unlock(&tasklist_lock);
> +out:
> + page_unlock_anon_vma(av);

If !av, this doesn't need an unlock and in fact crashes due to
dereferencing NULL.

> +static int poison_page_prepare(struct page *p, unsigned long pfn, int trapno)
> +{
> + if (PagePoison(p)) {
> + printk(KERN_ERR
> + "MCE: Error for already poisoned page at %lx\n", pfn);
> + return -1;
> + }
> + SetPagePoison(p);

TestSetPagePoison()?