[Intel-gfx] 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