Messages in this thread | | | Subject | Re: [mm 4.15-rc8] Random oopses under memory pressure. | From | Dave Hansen <> | Date | Wed, 17 Jan 2018 14:04:51 -0800 |
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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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