On 01/20/2020 03:52 PM, Michal Hocko wrote: > On Mon 20-01-20 11:04:14, Wei Yang wrote: >> Now we can pass all bad reasons to __dump_page(). > And we do we want to do that? The dump of the page will tell us the > whole story so a single and the most important reason sounds like a > better implementation. The code is also more subtle because each caller > of the function has to be aware of how many reasons there might be. > Not to mention that you need a room for 5 pointers on the stack and this > and page allocator might be called from deeper call chains. > Two paths which lead to __dump_page(), dump_page() and bad_page(). Callers of dump_page() can give a single reason what they consider the most important which leads to page dumping. This makes sense but gets trickier in bad_page() path. At present, free_pages_check_bad() and check_new_page_bad() has a sequence of 'if' statements which decides "most important" reason for __dump_page() without much rationale and similar in case of free_tail_pages_check() as well. As all information about the page for corresponding reasons are printed with __dump_page() anyways, do free_pages_check_bad() or check_new_page_bad() really need to provide any particular single reason ?
