Re: Possible regression in drm/i915 driver: memleak

[Tvrtko Ursulin]

Hi,

On 20/12/2022 15:22, srinivas pandruvada wrote:
> +Added DRM mailing list and maintainers
>
> On Tue, 2022-12-20 at 15:33 +0100, Mirsad Todorovac wrote:
> > Hi all,
> >
> > I have been unsuccessful to find any particular Intel i915 maintainer
> > emails, so my best bet is to post here, as you will must assuredly
> > already know them.

For future reference you can use ${kernel_dir}/scripts/get_maintainer.pl -f ...

> > The problem is a kernel memory leak that is repeatedly occurring
> > triggered during the execution of Chrome browser under the latest
> > 6.1.0+
> > kernel of this morning and Almalinux 8.6 on a Lenovo desktop box
> > with Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz CPU.
> >
> > The build is with KMEMLEAK, KASAN and MGLRU turned on during the
> > build,
> > on a vanilla mainline kernel from Mr. Torvalds' tree.
> >
> > The leaks look like this one:
> >
> > unreferenced object 0xffff888131754880 (size 64):
> >     comm "chrome", pid 13058, jiffies 4298568878 (age 3708.084s)
> >     hex dump (first 32 bytes):
> >       01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > ................
> >       00 00 00 00 00 00 00 00 00 80 1e 3e 83 88 ff ff
> > ...........>....
> >     backtrace:
> >       [<ffffffff9e9b5542>] slab_post_alloc_hook+0xb2/0x340
> >       [<ffffffff9e9bbf5f>] __kmem_cache_alloc_node+0x1bf/0x2c0
> >       [<ffffffff9e8f767a>] kmalloc_trace+0x2a/0xb0
> >       [<ffffffffc08dfde5>] drm_vma_node_allow+0x45/0x150 [drm]
> >       [<ffffffffc0b33315>] __assign_mmap_offset_handle+0x615/0x820
> > [i915]
> >       [<ffffffffc0b34057>] i915_gem_mmap_offset_ioctl+0x77/0x110
> > [i915]
> >       [<ffffffffc08bc5e1>] drm_ioctl_kernel+0x181/0x280 [drm]
> >       [<ffffffffc08bc9cd>] drm_ioctl+0x2dd/0x6a0 [drm]
> >       [<ffffffff9ea54744>] __x64_sys_ioctl+0xc4/0x100
> >       [<ffffffff9fbc0178>] do_syscall_64+0x58/0x80
> >       [<ffffffff9fc000aa>] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> >
> > The complete list of leaks in attachment, but they seem similar or
> > the same.
> >
> > Please find attached lshw and kernel build config file.
> >
> > I will probably check the same parms on my laptop at home, which is
> > also
> > Lenovo, but a different hw config and Ubuntu 22.10.

Could you try the below patch?

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index c3ea243d414d..0b07534c203a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -679,9 +679,10 @@ mmap_offset_attach(struct drm_i915_gem_object *obj,
 insert:
        mmo = insert_mmo(obj, mmo);
        GEM_BUG_ON(lookup_mmo(obj, mmap_type) != mmo);
-out:
+
        if (file)
                drm_vma_node_allow(&mmo->vma_node, file);
+out:
        return mmo;

 err:

Maybe it is not the best fix but curious to know if it will make the leak go away.

Regards,

Tvrtko