On Thu 18-03-21 11:02:17, Johannes Weiner wrote:

On Thu, Mar 18, 2021 at 03:01:25PM +0100, Michal Hocko wrote:

quoted

On Wed 17-03-21 18:59:59, Shakeel Butt wrote:

quoted

The function swap_readpage() (and other functions it call) extracts swap
entry from page->private. However for SWP_SYNCHRONOUS_IO, the kernel
skips the swapcache and thus we need to manually set the page->private
with the swap entry before calling swap_readpage().

One thing that is not really clear to me is whether/why this is only
needed with your patch. Can you expand a bit on that please? Maybe I am
just missing something obvious but I just do not see any connection.

It was always needed, his original patch erroneously removed it.

Ahh, I can see it now. I must have been blind. Thanks!

-- 
Michal Hocko
SUSE Labs