Subject: Re: [PATCH] mm/slab: improve kmem_cache_alloc_bulk

From: Christoph Hellwig <[email-masked]>
Date: Wed, 27 May 2026 14:20:13 +0200

On Wed, May 27, 2026 at 11:38:21AM +0200, Vlastimil Babka (SUSE) wrote:
> On 5/27/26 09:02, Christoph Hellwig wrote:
> > The kmem_cache_alloc_bulk return value is weird.  It returns the number
> > of allocated objects, but that must always be 0 or the requested number
> > based on the implementations and the handling in the callers, but that
> > assumption is not actually documented anywhere, which confuses automated
> > review tools.
> > 
> > Fix this by returning a bool if the allocation succeeded and adding a
> > kerneldoc comment explaining the API.
> > 
> > Signed-off-by: Christoph Hellwig <[email-masked]>
> 
> Would 0 / -ENOMEM be more like what people would expect? I guess both that
> and bool are better than the current API.

I find an errno return where the API could not return anything but the
specific error code a bit odd.  But even that would be a lot better
than the current version.