Re: [PATCH] Revert "mm/vunmap: add cond_resched() in vunmap_pmd_range"

[Minchan Kim]

On Tue, Nov 17, 2020 at 01:56:32PM +0000, Christoph Hellwig wrote:
> Btw, I remember that the whole vmalloc magic in zsmalloc was only giving
> a small benefit for a few niche use cases.  Given that it generally has
> very strange interaction with the vmalloc core, including using various
> APIs not used by any driver I'm going to ask once again why we can't
> just drop the CONFIG_ZSMALLOC_PGTABLE_MAPPING case entirely?

Yub, I remeber the discussion. 
https://lore.kernel.org/linux-mm/20200416203736.GB50092@xxxxxxxxxx/

I wanted to remove it but 30% gain made me think again before
deciding to drop it.
Since it continue to make problems and Linux is approaching to
deprecate the 32bit machines, I think it would be better to drop it
rather than inventing weird workaround.

Ccing Tony since omap2plus have used it by default for just in case.