| Message ID | 20240404070702.2744-5-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | page_owner: Fix refcount imbalance and print fixup | expand |
On 4/4/24 9:07 AM, Oscar Salvador wrote: > 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(). > > Fixes: 765973a09803 ("mm,page_owner: display all stacks and their count") > Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/page_owner.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index b4476f45b376..9bef0b442863 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -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; > } >
diff --git a/mm/page_owner.c b/mm/page_owner.c index b4476f45b376..9bef0b442863 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -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; }
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(). Fixes: 765973a09803 ("mm,page_owner: display all stacks and their count") Signed-off-by: Oscar Salvador <osalvador@suse.de> --- mm/page_owner.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)