On Fri 20-02-26 17:50:44, David Hildenbrand (Arm) via Lsf-pc wrote:

On 2/20/26 05:49, Matthew Wilcox wrote:

quoted

And if no pages from the file have been mmaped yet, they cannot be pinned
or mlocked.

Is there some other way for someone to block a page from getting evicted
from the pagecache?

We have this memfd_pin_folios() thing, but I don't think we have something
comparable for ordinary pagecache files.

... putting them into a pipe and never reading from the pipe maybe (I assume
that's what splice() does, but not sure if it actually places the pages in
there or whether it creates a copy first)?

Standard splice copies data first (it's using standard IO callbacks such as
->read_iter) so that doesn't pin page cache AFAICT. Only vmsplice(2) does
but that requires mmap.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR