From: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Subject: mm/page_owner: fix recursion bug after changing skip entries
This patch fixes 5f48f0bd4e368425 ("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/1521607043-34670-1-git-send-email-maninder1.s@xxxxxxxxxxx
Fixes: 5f48f0bd4e36 ("mm, page_owner: skip unnecessary stack_trace entries")
Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Signed-off-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Ayush Mittal <ayush.m@xxxxxxxxxxx>
Cc: Prakash Gupta <guptap@xxxxxxxxxxxxxx>
Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Cc: Vasyl Gomonovych <gomonovych@xxxxxxxxx>
Cc: Amit Sahrawat <a.sahrawat@xxxxxxxxxxx>
Cc: <pankaj.m@xxxxxxxxxxx>
Cc: Vaneet Narang <v.narang@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_owner.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN mm/page_owner.c~mm-page_owner-fix-recursion-bug-after-changing-skip-entries mm/page_owner.c
--- a/mm/page_owner.c~mm-page_owner-fix-recursion-bug-after-changing-skip-entries
+++ a/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;
}
_
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