Re: [PATCH] mm: add prototype for __add_to_page_cache_locked()

[Christoph Hellwig]

On Wed, Dec 23, 2020 at 12:11:36PM +0000, Matthew Wilcox wrote:
> On Wed, Dec 23, 2020 at 08:31:26AM +0000, Christoph Hellwig wrote:
> > Can we please make the eBPF code stop referencing this function instead
> > of papering over this crap?  It has no business poking into page cache
> > internals.
> 
> The reference from the BPF code is simply "you can inject errors here".
> And I think we want to be able to inject errors to test the error paths,
> no?

Something that expects a symbol to be global is just pretty broken.
I think it need to change so that whatever instrumentation is done can
coexist with a static function.