Re: [PATCH v2] powerpc: msi: mark bitmap with kmemleak_not_leak()

[Catalin Marinas <catalin.marinas@arm.com>]

On Tue, Sep 15, 2015 at 08:14:08PM +0300, Denis Kirjanov wrote:
> diff --git a/arch/powerpc/include/asm/msi_bitmap.h b/arch/powerpc/include=
/asm/msi_bitmap.h
> index 97ac3f4..9a1d2fb 100644
> --- a/arch/powerpc/include/asm/msi_bitmap.h
> +++ b/arch/powerpc/include/asm/msi_bitmap.h
> @@ -19,6 +19,7 @@ struct msi_bitmap {
>  =09unsigned long=09=09*bitmap;
>  =09spinlock_t=09=09lock;
>  =09unsigned int=09=09irq_count;
> +=09bool=09=09bitmap_from_slab;

Nitpick: same alignment for bitmap_from_slab with irq_count etc. (unless
it's just my mail client).

>  };
> =20
>  int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int num);
> diff --git a/arch/powerpc/sysdev/msi_bitmap.c b/arch/powerpc/sysdev/msi_b=
itmap.c
> index 73b64c7..305ebe3 100644
> --- a/arch/powerpc/sysdev/msi_bitmap.c
> +++ b/arch/powerpc/sysdev/msi_bitmap.c
> @@ -11,6 +11,7 @@
>  #include <linux/slab.h>
>  #include <linux/kernel.h>
>  #include <linux/bitmap.h>
> +#include <linux/bootmem.h>
>  #include <asm/msi_bitmap.h>
>  #include <asm/setup.h>
> =20
> @@ -122,7 +123,12 @@ int msi_bitmap_alloc(struct msi_bitmap *bmp, unsigne=
d int irq_count,
>  =09size =3D BITS_TO_LONGS(irq_count) * sizeof(long);
>  =09pr_debug("msi_bitmap: allocator bitmap size is 0x%x bytes\n", size);
> =20
> -=09bmp->bitmap =3D zalloc_maybe_bootmem(size, GFP_KERNEL);
> +=09if (slab_is_available()) {
> +=09=09bmp->bitmap =3D kzalloc(size, GFP_KERNEL);
> +=09=09bmp->bitmap_from_slab =3D true;
> +=09} else
> +=09=09bmp->bitmap =3D memblock_virt_alloc(size, 0);

I don't think bmp->bitmap_from_slab is always initialised, so you need
to explicitly set it to false here.

> +
>  =09if (!bmp->bitmap) {
>  =09=09pr_debug("msi_bitmap: ENOMEM allocating allocator bitmap!\n");
>  =09=09return -ENOMEM;
> @@ -138,7 +144,8 @@ int msi_bitmap_alloc(struct msi_bitmap *bmp, unsigned=
 int irq_count,
> =20
>  void msi_bitmap_free(struct msi_bitmap *bmp)
>  {
> -=09/* we can't free the bitmap we don't know if it's bootmem etc. */
> +=09if (bmp->bitmap_from_slab)
> +=09=09kfree(bmp->bitmap);
>  =09of_node_put(bmp->of_node);
>  =09bmp->bitmap =3D NULL;
>  }
> @@ -200,11 +207,11 @@ static void __init test_basics(void)
>  =09WARN_ON(rc < 0 && rc % 128 !=3D 0);
> =20
>  =09msi_bitmap_free(&bmp);
> +=09if (!bmp.bitmap_from_slab)
> +=09=09kmemleak_not_leak(bmp.bitmap);

As I mentioned in the other thread, I think you can call
kmemleak_not_leak() immediately after memblock_virt_alloc() (together
with a comment that this is never going to be freed). That would match
the other kmemleak API uses throughout the kernel.

--=20
Catalin