mm,page_owner: fix printing of stack records

When seq_* code sees that its buffer overflowed, it re-allocates a bigger
onecand calls seq_operations->start() callback again.  stack_start()
naively though that if it got called again, it meant that the old record
got already printed so it returned the next object, but that is not true.

The consequence of that is that every time stack_stop() -> stack_start()
get called because we needed a bigger buffer, stack_start() will skip
entries, and those will not be printed.

Fix it by not advancing to the next object in stack_start().

Link: https://lkml.kernel.org/r/20240404070702.2744-5-osalvador@suse.de
Fixes: 765973a098 ("mm,page_owner: display all stacks and their count")
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oscar Salvador 2024-04-04 09:07:02 +02:00 committed by Andrew Morton
parent 718b1f3373
commit 7401745801

View file

@ -872,13 +872,11 @@ static void *stack_start(struct seq_file *m, loff_t *ppos)
* value of stack_list.
*/
stack = smp_load_acquire(&stack_list);
m->private = stack;
} else {
stack = m->private;
stack = stack->next;
}
m->private = stack;
return stack;
}