Re: [patch v2 4/4] mm, mempool: poison elements backed by page allocator

From: David Rientjes
Date: Thu Apr 02 2015 - 21:04:11 EST

On Tue, 31 Mar 2015, Andrey Ryabinin wrote:

> > We don't have a need to set PAGE_EXT_DEBUG_POISON on these pages sitting
> > in the reserved pool, nor do we have a need to do kmap_atomic() since it's
> > already mapped and must be mapped to be on the reserved pool, which is
> > handled by mempool_free().
> >
> Hmm.. I just realized that this statement might be wrong.
> Why pages has to be mapped to be on reserved pool?
> mempool could be used for highmem pages and there is no need to kmap()
> until these pages will be used.
> drbd (drivers/block/drbd) already uses mempool for highmem pages:

Yes, you're exactly right, I didn't see this because the mempool is
created in one file and then solely used in another file, but regardless
we still need protection from this usecase.
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