| Message ID | 20240306123217.29774-2-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | page_owner: Fixup and cleanup | expand |
On 3/6/24 13:32, Oscar Salvador wrote: > Although the retrieval of the stack_records for {dummy,failure}_handle > happen when page_owner gets initialized, there seems to be some situations > where stackdepot space has been already depleted by then, so we get > 0-handles which make stack_records being NULL for those cases. > > Be careful to 1) only bump stack_records refcount and 2) only access > stack_record fields if we actually have a non-null stack_record between > hands. > > Reported-by: kernel test robot <oliver.sang@intel.com> > Closes: https://lore.kernel.org/oe-lkp/202403051032.e2f865a-lkp@intel.com > Fixes: 4bedfb314bdd ("mm,page_owner: implement the tracking of the stacks count") > Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/page_owner.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 033e349f6479..7163a1c44ccf 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -107,8 +107,10 @@ static __init void init_page_owner(void) > /* Initialize dummy and failure stacks and link them to stack_list */ > dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); > failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle); > - refcount_set(&dummy_stack.stack_record->count, 1); > - refcount_set(&failure_stack.stack_record->count, 1); > + if (dummy_stack.stack_record) > + refcount_set(&dummy_stack.stack_record->count, 1); > + if (failure_stack.stack_record) > + refcount_set(&failure_stack.stack_record->count, 1); > dummy_stack.next = &failure_stack; > stack_list = &dummy_stack; > } > @@ -856,6 +858,9 @@ static int stack_print(struct seq_file *m, void *v) > unsigned long nr_entries; > struct stack_record *stack_record = stack->stack_record; > > + if (!stack->stack_record) > + return 0; > + > nr_entries = stack_record->size; > entries = stack_record->entries; > stack_count = refcount_read(&stack_record->count) - 1;
diff --git a/mm/page_owner.c b/mm/page_owner.c index 033e349f6479..7163a1c44ccf 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -107,8 +107,10 @@ static __init void init_page_owner(void) /* Initialize dummy and failure stacks and link them to stack_list */ dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle); - refcount_set(&dummy_stack.stack_record->count, 1); - refcount_set(&failure_stack.stack_record->count, 1); + if (dummy_stack.stack_record) + refcount_set(&dummy_stack.stack_record->count, 1); + if (failure_stack.stack_record) + refcount_set(&failure_stack.stack_record->count, 1); dummy_stack.next = &failure_stack; stack_list = &dummy_stack; } @@ -856,6 +858,9 @@ static int stack_print(struct seq_file *m, void *v) unsigned long nr_entries; struct stack_record *stack_record = stack->stack_record; + if (!stack->stack_record) + return 0; + nr_entries = stack_record->size; entries = stack_record->entries; stack_count = refcount_read(&stack_record->count) - 1;
Although the retrieval of the stack_records for {dummy,failure}_handle happen when page_owner gets initialized, there seems to be some situations where stackdepot space has been already depleted by then, so we get 0-handles which make stack_records being NULL for those cases. Be careful to 1) only bump stack_records refcount and 2) only access stack_record fields if we actually have a non-null stack_record between hands. Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202403051032.e2f865a-lkp@intel.com Fixes: 4bedfb314bdd ("mm,page_owner: implement the tracking of the stacks count") Signed-off-by: Oscar Salvador <osalvador@suse.de> --- mm/page_owner.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)