On 3/14/24 00:42, Oscar Salvador wrote:
> Prior to 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count")
> the only place where page_owner could potentially go into recursion due to
> its need of allocating more memory was in save_stack(), which ends up calling
> into stackdepot code with the possibility of allocating memory.
>
> We made sure to guard against that by signaling that the current task was
> already in page_owner code, so in case a recursion attempt was made, we
> could catch that and return dummy_handle.
>
> After above commit, a new place in page_owner code was introduced where we
> could allocate memory, meaning we could go into recursion would we take that
> path.
>
> Make sure to signal that we are in page_owner in that codepath as well.
> Move the guard code into two helpers {un}set_current_in_page_owner()
> and use them prior to calling in the two functions that might allocate
> memory.
>
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Fixes: 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count")
> ---
> mm/page_owner.c | 30 +++++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> @@ -292,7 +302,9 @@ noinline void __set_page_owner(struct page *page, unsigned short order,
> return;
> __set_page_owner_handle(page_ext, handle, order, gfp_mask);
> page_ext_put(page_ext);
> + set_current_in_page_owner();
> inc_stack_record_count(handle, gfp_mask);
> + unset_current_in_page_owner();
This is because of the kmalloc() in add_stack_record_to_list() right? Why
not wrap just that then?
> }
>
> void __set_page_owner_migrate_reason(struct page *page, int reason)
