Re: kmemleak: 1157 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

[Michael Ellerman <mpe@ellerman.id.au>]

Mathieu Malaterre <malat@debian.org> writes:
> Hi there,
>
> Is there a way to dump more context (somewhere in of tree
> flattening?). I cannot make sense of the following:

Hmm. Not that I know of.

Those don't look related to OF flattening/unflattening. That's just
sysfs setup based on the unflattened device tree.

The allocations are happening in safe_name() AFAICS.

int __of_add_property_sysfs(struct device_node *np, struct property *pp)
{
	...
	pp->attr.attr.name = safe_name(&np->kobj, pp->name);

And the free is in __of_sysfs_remove_bin_file():

void __of_sysfs_remove_bin_file(struct device_node *np, struct property *prop)
{
	if (!IS_ENABLED(CONFIG_SYSFS))
		return;

	sysfs_remove_bin_file(&np->kobj, &prop->attr);
	kfree(prop->attr.attr.name);


There is this check which could be failing leading to us not calling the
free at all:

void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
{
	/* at early boot, bail here and defer setup to of_init() */
	if (of_kset && of_node_is_attached(np))
		__of_sysfs_remove_bin_file(np, prop);
}


So maybe stick a printk() in there to see if you're hitting that
condition, eg something like:

	if (of_kset && of_node_is_attached(np))
		__of_sysfs_remove_bin_file(np, prop);
	else
		printk("%s: leaking prop %s on node %pOF\n", __func__, prop->attr.attr.name, np);


cheers

> kmemleak: 1157 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
>
> Where:
>
> # head -40 /sys/kernel/debug/kmemleak
> unreferenced object 0xdf44d180 (size 8):
>   comm "swapper", pid 1, jiffies 4294892297 (age 4766.460s)
>   hex dump (first 8 bytes):
>     62 61 73 65 00 00 00 00                          base....
>   backtrace:
>     [<0ca59825>] kstrdup+0x4c/0xb8
>     [<c8a79377>] kobject_set_name_vargs+0x34/0xc8
>     [<661b4c86>] kobject_add+0x78/0x120
>     [<c1416f27>] __of_attach_node_sysfs+0xa0/0x14c
>     [<2a143d10>] of_core_init+0x90/0x114
>     [<a353d0e1>] driver_init+0x30/0x48
>     [<84ed01b1>] kernel_init_freeable+0xfc/0x3fc
>     [<dc60f815>] kernel_init+0x20/0x110
>     [<faa1c5b0>] ret_from_kernel_thread+0x14/0x1c
> unreferenced object 0xdf44d178 (size 8):
>   comm "swapper", pid 1, jiffies 4294892297 (age 4766.460s)
>   hex dump (first 8 bytes):
>     6d 6f 64 65 6c 00 97 c8                          model...
>   backtrace:
>     [<0ca59825>] kstrdup+0x4c/0xb8
>     [<0eeb0a3b>] __of_add_property_sysfs+0x88/0x12c
>     [<f6c64af0>] __of_attach_node_sysfs+0xcc/0x14c
>     [<2a143d10>] of_core_init+0x90/0x114
>     [<a353d0e1>] driver_init+0x30/0x48
>     [<84ed01b1>] kernel_init_freeable+0xfc/0x3fc
>     [<dc60f815>] kernel_init+0x20/0x110
>     [<faa1c5b0>] ret_from_kernel_thread+0x14/0x1c
> unreferenced object 0xdf4021e0 (size 16):
>   comm "swapper", pid 1, jiffies 4294892297 (age 4766.460s)
>   hex dump (first 16 bytes):
>     63 6f 6d 70 61 74 69 62 6c 65 00 01 00 00 00 00  compatible......
>   backtrace:
>     [<0ca59825>] kstrdup+0x4c/0xb8
>     [<0eeb0a3b>] __of_add_property_sysfs+0x88/0x12c
>     [<f6c64af0>] __of_attach_node_sysfs+0xcc/0x14c
>     [<2a143d10>] of_core_init+0x90/0x114
>     [<a353d0e1>] driver_init+0x30/0x48
>     [<84ed01b1>] kernel_init_freeable+0xfc/0x3fc
>     [<dc60f815>] kernel_init+0x20/0x110
>     [<faa1c5b0>] ret_from_kernel_thread+0x14/0x1c