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SubjectRe: [PATCH 9/9] hugetlb: add corrupted hugepage counter
> +void increment_corrupted_huge_page(struct page *page);
> +void decrement_corrupted_huge_page(struct page *page);

nitpick: increment/decrement are not verbs.

> +void increment_corrupted_huge_page(struct page *hpage)
> +{
> + struct hstate *h = page_hstate(hpage);
> + spin_lock(&hugetlb_lock);
> + h->corrupted_huge_pages++;
> + spin_unlock(&hugetlb_lock);
> +}
> +
> +void decrement_corrupted_huge_page(struct page *hpage)
> +{
> + struct hstate *h = page_hstate(hpage);
> + spin_lock(&hugetlb_lock);
> + BUG_ON(!h->corrupted_huge_pages);

There is no point to have BUG_ON() here:

/*
* Don't use BUG() or BUG_ON() unless there's really no way out; one
* example might be detecting data structure corruption in the middle
* of an operation that can't be backed out of. If the (sub)system
* can somehow continue operating, perhaps with reduced functionality,
* it's probably not BUG-worthy.
*
* If you're tempted to BUG(), think again: is completely giving up
* really the *only* solution? There are usually better options, where
* users don't need to reboot ASAP and can mostly shut down cleanly.
*/


And there is a race case that (corrupted_huge_pages==0)!
Suppose the user space calls unpoison_memory() on a good pfn, and the page
happen to be hwpoisoned between lock_page() and TestClearPageHWPoison(),
corrupted_huge_pages will go negative.

Thanks,
Fengguang

> + h->corrupted_huge_pages--;
> + spin_unlock(&hugetlb_lock);
> +}


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