| Message ID | 20240214170157.17530-4-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | page_owner: print stacks and their outstanding allocations | expand |
On 2/14/24 18:01, Oscar Salvador wrote: > page_owner needs to increment a stack_record refcount when a new allocation > occurs, and decrement it on a free operation. > In order to do that, we need to have a way to get a stack_record from a > handle. > Implement __stack_depot_get_stack_record() which just does that, and make > it public so page_owner can use it. > > Also, traversing all stackdepot buckets comes with its own complexity, > plus we would have to implement a way to mark only those stack_records > that were originated from page_owner, as those are the ones we are > interested in. > For that reason, page_owner maintains its own list of stack_records, > because traversing that list is faster than traversing all buckets > while keeping at the same time a low complexity. > > For now, add to stack_list only the stack_records of dummy_handle and > failure_handle, and set their refcount of 1. > > Further patches will add code to increment or decrement stack_records > count on allocation and free operation. > > Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
On Thu, 15 Feb 2024 at 11:55, Vlastimil Babka <vbabka@suse.cz> wrote: > > On 2/14/24 18:01, Oscar Salvador wrote: > > page_owner needs to increment a stack_record refcount when a new allocation > > occurs, and decrement it on a free operation. > > In order to do that, we need to have a way to get a stack_record from a > > handle. > > Implement __stack_depot_get_stack_record() which just does that, and make > > it public so page_owner can use it. > > > > Also, traversing all stackdepot buckets comes with its own complexity, > > plus we would have to implement a way to mark only those stack_records > > that were originated from page_owner, as those are the ones we are > > interested in. > > For that reason, page_owner maintains its own list of stack_records, > > because traversing that list is faster than traversing all buckets > > while keeping at the same time a low complexity. > > > > For now, add to stack_list only the stack_records of dummy_handle and > > failure_handle, and set their refcount of 1. > > > > Further patches will add code to increment or decrement stack_records > > count on allocation and free operation. > > > > Signed-off-by: Oscar Salvador <osalvador@suse.de> > > Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > +1 Reviewed-by: Marco Elver <elver@google.com>
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index c4b5ad57c066..3c6caa5abc7c 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -178,6 +178,17 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, depot_stack_handle_t stack_depot_save(unsigned long *entries, unsigned int nr_entries, gfp_t gfp_flags); +/** + * __stack_depot_get_stack_record - Get a pointer to a stack_record struct + * + * @handle: Stack depot handle + * + * This function is only for internal purposes. + * + * Return: Returns a pointer to a stack_record struct + */ +struct stack_record *__stack_depot_get_stack_record(depot_stack_handle_t handle); + /** * stack_depot_fetch - Fetch a stack trace from stack depot * diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 4a661a6777da..3da6d7cfcdfb 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -687,6 +687,14 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, } EXPORT_SYMBOL_GPL(stack_depot_save); +struct stack_record *__stack_depot_get_stack_record(depot_stack_handle_t handle) +{ + if (!handle) + return NULL; + + return depot_fetch_stack(handle); +} + unsigned int stack_depot_fetch(depot_stack_handle_t handle, unsigned long **entries) { diff --git a/mm/page_owner.c b/mm/page_owner.c index 5634e5d890f8..33e342b15d9b 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -36,6 +36,14 @@ struct page_owner { pid_t free_tgid; }; +struct stack { + struct stack_record *stack_record; + struct stack *next; +}; +static struct stack dummy_stack; +static struct stack failure_stack; +static struct stack *stack_list; + static bool page_owner_enabled __initdata; DEFINE_STATIC_KEY_FALSE(page_owner_inited); @@ -95,6 +103,13 @@ static __init void init_page_owner(void) register_early_stack(); static_branch_enable(&page_owner_inited); init_early_allocated_pages(); + /* 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); + dummy_stack.next = &failure_stack; + stack_list = &dummy_stack; } struct page_ext_operations page_owner_ops = {
page_owner needs to increment a stack_record refcount when a new allocation occurs, and decrement it on a free operation. In order to do that, we need to have a way to get a stack_record from a handle. Implement __stack_depot_get_stack_record() which just does that, and make it public so page_owner can use it. Also, traversing all stackdepot buckets comes with its own complexity, plus we would have to implement a way to mark only those stack_records that were originated from page_owner, as those are the ones we are interested in. For that reason, page_owner maintains its own list of stack_records, because traversing that list is faster than traversing all buckets while keeping at the same time a low complexity. For now, add to stack_list only the stack_records of dummy_handle and failure_handle, and set their refcount of 1. Further patches will add code to increment or decrement stack_records count on allocation and free operation. Signed-off-by: Oscar Salvador <osalvador@suse.de> --- include/linux/stackdepot.h | 11 +++++++++++ lib/stackdepot.c | 8 ++++++++ mm/page_owner.c | 15 +++++++++++++++ 3 files changed, 34 insertions(+)