On Thu, 19 Jan 2023 13:14:45 -0800
Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx> wrote:
[...]
> page = pte_page(entry);
> - if (page != pagecache_page)
> + if (page_folio(page) != pagecache_folio)
> if (!trylock_page(page)) {
> need_wait_lock = 1;
> goto out_ptl;
> }
>
> - get_page(page);
> + folio_get(pagecache_folio);
>
We get a kernel crash on s390 in mprotect testcase from libhugetlbfs
testsuite, starting with next-20230120, bisected to this commit.
We get here with pagecache_folio == NULL, and crash in folio_get().
It doesn´t seem right to replace the get_page() with folio_get()
here, the matching put_page() at out_put_page: also wasn't changed
correspondingly. Also, pagecache_folio == NULL seems to be a valid
case here, on all architectures.
Reverting this folio_get() to get_page() fixes the crash. Not sure
though if I missed something. I think you only want to replace
pagecache_page with pagecache_folio, like in the rest of the commit,
and not page -> pagecache_folio for this get_page().
