Re: [STABLE PATCH] slub: make ->cpu_partial unsigned int

[Christopher Lameter]

On Thu, 27 Sep 2018, zhong jiang wrote:

> From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
>
>         /*
>          * cpu_partial determined the maximum number of objects
>          * kept in the per cpu partial lists of a processor.
>          */
>
> Can't be negative.

True.

> I hit a real issue that it will result in a large number of memory leak.
> Because Freeing slabs are in interrupt context. So it can trigger this issue.
> put_cpu_partial can be interrupted more than once.
> due to a union struct of lru and pobjects in struct page, when other core handles
> page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will
> result in pobjects being a negative value(0xdead0000). Therefore, a large number
> of slabs will be added to per_cpu partial list.

That sounds like it needs more investigation. Concurrent use of page
fields for other purposes can cause serious bugs.

>
> I had posted the issue to community before. The detailed issue description is as follows.

I did not see it. Please make sure to CC the maintainers.