Hello, D. Wythe!

On Fri, Jan 23, 2026 at 07:55:17PM +0100, Uladzislau Rezki wrote:

quoted

On Fri, Jan 23, 2026 at 04:23:48PM +0800, D. Wythe wrote:

quoted

find_vm_area() provides a way to find the vm_struct associated with a
virtual address. Export this symbol to modules so that modularized
subsystems can perform lookups on vmalloc addresses.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 mm/vmalloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ecbac900c35f..3eb9fe761c34 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c

@@ -3292,6 +3292,7 @@ struct vm_struct *find_vm_area(const void *addr)
 
 	return va->vm;
 }
+EXPORT_SYMBOL_GPL(find_vm_area);
 

This is internal. We can not just export it.

--
Uladzislau Rezki

Hi Uladzislau,

Thank you for the feedback. I agree that we should avoid exposing
internal implementation details like struct vm_struct to external
subsystems.

Following Christoph's suggestion, I'm planning to encapsulate the page
order lookup into a minimal helper instead:

unsigned int vmalloc_page_order(const void *addr){
	struct vm_struct *vm;
 	vm = find_vm_area(addr);
	return vm ? vm->page_order : 0;
}
EXPORT_SYMBOL_GPL(vmalloc_page_order);

Does this approach look reasonable to you? It would keep the vm_struct
layout private while satisfying the optimization needs of SMC.

Could you please clarify why you need info about page_order? I have not
looked at your second patch.

Thanks!

--
Uladzislau Rezki