On 11/5/20 11:55 PM, Christoph Hellwig wrote:
On Thu, Nov 05, 2020 at 04:51:42PM -0800, Ralph Campbell wrote:
+extern void prep_transhuge_device_private_page(struct page *page);
No need for the extern.
Right, I was just copying the style.
Would you like to see a preparatory patch that removes extern for the other
declarations in huge_mm.h?
+static inline void prep_transhuge_device_private_page(struct page *page)
+{
+}
Is the code to call this even reachable if THP support is configured
out? If not just declaring it unconditionally and letting dead code
elimination do its job might be a tad cleaner.
The HMM test driver depends on TRANSPARENT_HUGEPAGE but the nouveau SVM
option doesn't and SVM is still useful if TRANSPARENT_HUGEPAGE is not configured.
The problem with defining prep_transhuge_device_private_page() in huge_mm.h
as a static inline function is that prep_compound_page() and prep_transhuge_page()
would have to be EXPORT_SYMBOL_GPL which are currently mm internal only.
The intent is to make this helper callable by separate device driver modules
using struct pages created with memremap_pages().
+void prep_transhuge_device_private_page(struct page *page)
I think a kerneldoc comment explaining what this function is useful for
would be helpful.
That is a good idea. I'll add it to v4.
