From d09683c6ef03650950d8f1588b09c833377de27d Mon Sep 17 00:00:00 2001 From: Mauricio Faria de Oliveira Date: Wed, 1 Oct 2025 14:56:10 -0300 Subject: [PATCH] mm/page_owner: add debugfs file 'show_stacks_handles' Add the file 'show_stacks_handles' to show just stack traces and their handles, in order to resolve stack traces and handles (i.e., to identify the stack traces for handles in previous reads from 'show_handles'). All stacks/handles must show up, regardless of their number of pages, that might have become zero or no longer make 'count_threshold', but made it in previous reads from 'show_handles' -- and need to be resolved later. P.S.: now, print the extra newline independently of the number of pages. Link: https://lkml.kernel.org/r/20251001175611.575861-5-mfo@igalia.com Signed-off-by: Mauricio Faria de Oliveira Cc: Brendan Jackman Cc: Johannes Weiner Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/page_owner.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index fe788f07b578..9c67bb8fb1d9 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -916,7 +916,8 @@ static int stack_print(struct seq_file *m, void *v) nr_base_pages = refcount_read(&stack_record->count) - 1; - if (nr_base_pages < 1 || nr_base_pages < page_owner_pages_threshold) + if (ctx->flags & STACK_PRINT_FLAG_PAGES && + (nr_base_pages < 1 || nr_base_pages < page_owner_pages_threshold)) return 0; if (ctx->flags & STACK_PRINT_FLAG_STACK) { @@ -928,7 +929,8 @@ static int stack_print(struct seq_file *m, void *v) if (ctx->flags & STACK_PRINT_FLAG_HANDLE) seq_printf(m, "handle: %d\n", stack_record->handle.handle); if (ctx->flags & STACK_PRINT_FLAG_PAGES) - seq_printf(m, "nr_base_pages: %d\n\n", nr_base_pages); + seq_printf(m, "nr_base_pages: %d\n", nr_base_pages); + seq_putc(m, '\n'); return 0; } @@ -1002,6 +1004,10 @@ static int __init pageowner_init(void) (void *)(STACK_PRINT_FLAG_HANDLE | STACK_PRINT_FLAG_PAGES), &page_owner_stack_operations); + debugfs_create_file("show_stacks_handles", 0400, dir, + (void *)(STACK_PRINT_FLAG_STACK | + STACK_PRINT_FLAG_HANDLE), + &page_owner_stack_operations); debugfs_create_file("count_threshold", 0600, dir, NULL, &proc_page_owner_threshold); -- 2.51.0