Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)

Vlastimil Babka
2019-09-24T21:19:36Z

On 9/23/19 7:51 PM, Darrick J. Wong wrote:
> On Mon, Sep 23, 2019 at 07:17:10PM +0200, David Sterba wrote:
>> On Mon, Sep 23, 2019 at 06:36:32PM +0200, Vlastimil Babka wrote:
>>> So if anyone thinks this is a good idea, please express it (preferably
>>> in a formal way such as Acked-by), otherwise it seems the patch will be
>>> dropped (due to a private NACK, apparently).
>
> Oh, I didn't realize ^^^^^^^^^^^^ that *some* of us are allowed the
> privilege of gutting a patch via private NAK without any of that open
> development discussion incovenience. <grumble>
>
> As far as XFS is concerned I merged Dave's series that checks the
> alignment of io memory allocations and falls back to vmalloc if the
> alignment won't work, because I got tired of scrolling past the endless
> discussion and bug reports and inaction spanning months.

I think it's a big fail of kmalloc API that you have to do that, and
especially with vmalloc, which has the overhead of setting up page
tables, and it's a waste for allocation requests smaller than page size.
I wish we could have nice things.