On 01/17/2018 01:51 PM, Linus Torvalds wrote:
> In fact, it seems to be such a fundamental bug that I suspect I'm
> entirely wrong, and full of shit. So it's an interesting and not
> _obviously_ incorrect theory, but I suspect I must be missing
> something.
I'll just note that a few of the pfns I decoded were smack in the middle
of the zone, not near either the high or low end of ZONE_NORMAL where we
would expect this cross-zone stuff to happen.
But I guess we could get similar wonkiness where 'struct page' is
screwed up in so many different ways if during buddy joining you do:
list_del(&buddy->lru);
and 'buddy' is off in another zone for which you do not hold the
spinlock. If we are somehow missing some locking, or double-allocating
a page, something like this would help:
static inline void rmv_page_order(struct page *page)
{
+ WARN_ON_ONCE(!PageBuddy(page));
__ClearPageBuddy(page);
set_page_private(page, 0);
}
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