4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Maninder Singh <[email protected]> [ Upstream commit 299815a4fba9f3c7a81434dba0072148f1690608 ] This patch fixes commit 5f48f0bd4e36 ("mm, page_owner: skip unnecessary stack_trace entries"). Because if we skip first two entries then logic of checking count value as 2 for recursion is broken and code will go in one depth recursion. so we need to check only one call of _RET_IP(__set_page_owner) while checking for recursion. Current Backtrace while checking for recursion:- (save_stack) from (__set_page_owner) // (But recursion returns true here) (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) // recursion should return true here (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask+) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) Correct Backtrace with fix: (save_stack) from (__set_page_owner) // recursion returned true here (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask+) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) Link: http://lkml.kernel.org/r/[email protected] Fixes: 5f48f0bd4e36 ("mm, page_owner: skip unnecessary stack_trace entries") Signed-off-by: Maninder Singh <[email protected]> Signed-off-by: Vaneet Narang <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Ayush Mittal <[email protected]> Cc: Prakash Gupta <[email protected]> Cc: Vinayak Menon <[email protected]> Cc: Vasyl Gomonovych <[email protected]> Cc: Amit Sahrawat <[email protected]> Cc: <[email protected]> Cc: Vaneet Narang <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/page_owner.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -123,13 +123,13 @@ void __reset_page_owner(struct page *pag static inline bool check_recursive_alloc(struct stack_trace *trace, unsigned long ip) { - int i, count; + int i; if (!trace->nr_entries) return false; - for (i = 0, count = 0; i < trace->nr_entries; i++) { - if (trace->entries[i] == ip && ++count == 2) + for (i = 0; i < trace->nr_entries; i++) { + if (trace->entries[i] == ip) return true; }
