diff options
Diffstat (limited to 'lib/alloc_tag.c')
| -rw-r--r-- | lib/alloc_tag.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 58991ab09d84..ed1bdcf1f8ab 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -6,7 +6,9 @@ #include <linux/kallsyms.h> #include <linux/module.h> #include <linux/page_ext.h> +#include <linux/pgalloc_tag.h> #include <linux/proc_fs.h> +#include <linux/rcupdate.h> #include <linux/seq_buf.h> #include <linux/seq_file.h> #include <linux/string_choices.h> @@ -758,8 +760,115 @@ static __init bool need_page_alloc_tagging(void) return mem_profiling_support; } +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG +/* + * Track page allocations before page_ext is initialized. + * Some pages are allocated before page_ext becomes available, leaving + * their codetag uninitialized. Track these early PFNs so we can clear + * their codetag refs later to avoid warnings when they are freed. + * + * Early allocations include: + * - Base allocations independent of CPU count + * - Per-CPU allocations (e.g., CPU hotplug callbacks during smp_init, + * such as trace ring buffers, scheduler per-cpu data) + * + * For simplicity, we fix the size to 8192. + * If insufficient, a warning will be triggered to alert the user. + * + * TODO: Replace fixed-size array with dynamic allocation using + * a GFP flag similar to ___GFP_NO_OBJ_EXT to avoid recursion. + */ +#define EARLY_ALLOC_PFN_MAX 8192 + +static unsigned long early_pfns[EARLY_ALLOC_PFN_MAX] __initdata; +static atomic_t early_pfn_count __initdata = ATOMIC_INIT(0); + +static void __init __alloc_tag_add_early_pfn(unsigned long pfn) +{ + int old_idx, new_idx; + + do { + old_idx = atomic_read(&early_pfn_count); + if (old_idx >= EARLY_ALLOC_PFN_MAX) { + pr_warn_once("Early page allocations before page_ext init exceeded EARLY_ALLOC_PFN_MAX (%d)\n", + EARLY_ALLOC_PFN_MAX); + return; + } + new_idx = old_idx + 1; + } while (!atomic_try_cmpxchg(&early_pfn_count, &old_idx, new_idx)); + + early_pfns[old_idx] = pfn; +} + +typedef void alloc_tag_add_func(unsigned long pfn); +static alloc_tag_add_func __rcu *alloc_tag_add_early_pfn_ptr __refdata = + RCU_INITIALIZER(__alloc_tag_add_early_pfn); + +void alloc_tag_add_early_pfn(unsigned long pfn) +{ + alloc_tag_add_func *alloc_tag_add; + + if (static_key_enabled(&mem_profiling_compressed)) + return; + + rcu_read_lock(); + alloc_tag_add = rcu_dereference(alloc_tag_add_early_pfn_ptr); + if (alloc_tag_add) + alloc_tag_add(pfn); + rcu_read_unlock(); +} + +static void __init clear_early_alloc_pfn_tag_refs(void) +{ + unsigned int i; + + if (static_key_enabled(&mem_profiling_compressed)) + return; + + rcu_assign_pointer(alloc_tag_add_early_pfn_ptr, NULL); + /* Make sure we are not racing with __alloc_tag_add_early_pfn() */ + synchronize_rcu(); + + for (i = 0; i < atomic_read(&early_pfn_count); i++) { + unsigned long pfn = early_pfns[i]; + + if (pfn_valid(pfn)) { + struct page *page = pfn_to_page(pfn); + union pgtag_ref_handle handle; + union codetag_ref ref; + + if (get_page_tag_ref(page, &ref, &handle)) { + /* + * An early-allocated page could be freed and reallocated + * after its page_ext is initialized but before we clear it. + * In that case, it already has a valid tag set. + * We should not overwrite that valid tag with CODETAG_EMPTY. + * + * Note: there is still a small race window between checking + * ref.ct and calling set_codetag_empty(). We accept this + * race as it's unlikely and the extra complexity of atomic + * cmpxchg is not worth it for this debug-only code path. + */ + if (ref.ct) { + put_page_tag_ref(handle); + continue; + } + + set_codetag_empty(&ref); + update_page_tag_ref(handle, &ref); + put_page_tag_ref(handle); + } + } + + } +} +#else /* !CONFIG_MEM_ALLOC_PROFILING_DEBUG */ +static inline void __init clear_early_alloc_pfn_tag_refs(void) {} +#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ + static __init void init_page_alloc_tagging(void) { + clear_early_alloc_pfn_tag_refs(); } struct page_ext_operations page_alloc_tagging_ops = { |