On 8/4/20 11:48 AM, Matthew Wilcox wrote:
On Tue, Aug 04, 2020 at 11:39:43AM -0700, John Hubbard wrote:+static inline int __compound_mapcount(struct page *page) +{ + page = compound_head(page); + return atomic_read(compound_mapcount_ptr(page)) + 1; +}I'd suggest instead: static inline int head_mapcount(struct page *head) { return atomic_read(compound_mapcount_ptr(head)) + 1; }+static inline int dump_page_compound_mapcount(struct page *page) +{ + if (WARN_ON_ONCE(!PageCompound(page))) + return 0; + return __compound_mapcount(page); }And just dropping this ... it shouldn't be used outside mm/debug.c anyway.
Yes, that's cleaner. I'll send a v2 that is not a reply, so that Andrew can spot it more easily. OK to add your "Suggested-by:" to that?
Thinking about it, we'll get the hint later that this is not to be trusted when the flags from the page do not include 'head'.
Good point. I think this will work out pretty well, then. thanks, -- John Hubbard NVIDIA
