From 7ddeb91f5b03f25995861e9b2e1eb766aa528892 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 6 Feb 2025 11:45:36 +0000 Subject: [PATCH] mm: kmemleak: add support for dumping physical and __percpu object info Patch series "mm: kmemleak: Usability improvements". Following a recent false positive tracking that led to commit 488b5b9eca68 ("mm: kmemleak: fix upper boundary check for physical address objects"), I needed kmemleak to give me more debug information about the objects it is tracking. This lead to the first patch of this series. The second patch changes the kmemleak-test module to show the raw pointers for debugging purposes. This patch (of 2): Currently, echo dump=... > /sys/kernel/debug/kmemleak only looks up the main virtual address object tree. However, for debugging, it's useful to dump information about physical address and __percpu objects. Search all three object trees for the dump= command and also print the type of the object if not virtual: "(phys)" or "(percpu)". In addition, allow search by alias (pointer within the object). Link: https://lkml.kernel.org/r/20250206114537.2597764-1-catalin.marinas@arm.com Link: https://lkml.kernel.org/r/20250206114537.2597764-2-catalin.marinas@arm.com Signed-off-by: Catalin Marinas Signed-off-by: Andrew Morton --- mm/kmemleak.c | 52 ++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 39 insertions(+), 13 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index c6ed68604136a..c12cef3eeb32a 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -352,6 +352,15 @@ static bool unreferenced_object(struct kmemleak_object *object) jiffies_last_scan); } +static const char *__object_type_str(struct kmemleak_object *object) +{ + if (object->flags & OBJECT_PHYS) + return " (phys)"; + if (object->flags & OBJECT_PERCPU) + return " (percpu)"; + return ""; +} + /* * Printing of the unreferenced objects information to the seq file. The * print_unreferenced function must be called with the object->lock held. @@ -364,8 +373,9 @@ static void print_unreferenced(struct seq_file *seq, unsigned int nr_entries; nr_entries = stack_depot_fetch(object->trace_handle, &entries); - warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n", - object->pointer, object->size); + warn_or_seq_printf(seq, "unreferenced object%s 0x%08lx (size %zu):\n", + __object_type_str(object), + object->pointer, object->size); warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n", object->comm, object->pid, object->jiffies); hex_dump_object(seq, object); @@ -384,10 +394,10 @@ static void print_unreferenced(struct seq_file *seq, */ static void dump_object_info(struct kmemleak_object *object) { - pr_notice("Object 0x%08lx (size %zu):\n", - object->pointer, object->size); + pr_notice("Object%s 0x%08lx (size %zu):\n", + __object_type_str(object), object->pointer, object->size); pr_notice(" comm \"%s\", pid %d, jiffies %lu\n", - object->comm, object->pid, object->jiffies); + object->comm, object->pid, object->jiffies); pr_notice(" min_count = %d\n", object->min_count); pr_notice(" count = %d\n", object->count); pr_notice(" flags = 0x%x\n", object->flags); @@ -1998,25 +2008,41 @@ static int kmemleak_open(struct inode *inode, struct file *file) return seq_open(file, &kmemleak_seq_ops); } -static int dump_str_object_info(const char *str) +static bool __dump_str_object_info(unsigned long addr, unsigned int objflags) { unsigned long flags; struct kmemleak_object *object; + + object = __find_and_get_object(addr, 1, objflags); + if (!object) + return false; + + raw_spin_lock_irqsave(&object->lock, flags); + dump_object_info(object); + raw_spin_unlock_irqrestore(&object->lock, flags); + + put_object(object); + + return true; +} + +static int dump_str_object_info(const char *str) +{ unsigned long addr; + bool found = false; if (kstrtoul(str, 0, &addr)) return -EINVAL; - object = find_and_get_object(addr, 0); - if (!object) { + + found |= __dump_str_object_info(addr, 0); + found |= __dump_str_object_info(addr, OBJECT_PHYS); + found |= __dump_str_object_info(addr, OBJECT_PERCPU); + + if (!found) { pr_info("Unknown object at 0x%08lx\n", addr); return -EINVAL; } - raw_spin_lock_irqsave(&object->lock, flags); - dump_object_info(object); - raw_spin_unlock_irqrestore(&object->lock, flags); - - put_object(object); return 0; } -- 2.47.2