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mm: kmemleak: add support for dumping physical and __percpu object info

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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 <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Catalin Marinas 2025-02-06 11:45:36 +00:00 committed by Andrew Morton
parent 9a5b183941
commit 7ddeb91f5b
1 changed files with 40 additions and 14 deletions
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54
mm/kmemleak.c
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@ -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;
unsigned long addr;
if (kstrtoul(str, 0, &addr))
return -EINVAL;
object = find_and_get_object(addr, 0);
if (!object) {
pr_info("Unknown object at 0x%08lx\n", addr);
return -EINVAL;
}
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;
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;
}
return 0;
}