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Date: Wed, 31 Jan 2024 08:54:46 -0600
From: Lucas De Marchi <lucas.demarchi@intel.com>
To: wangxiaoming321 <xiaoming.wang@intel.com>
CC: <ogabbay@kernel.org>, <thomas.hellstrom@linux.intel.com>,
	<maarten.lankhorst@linux.intel.com>, <mripard@kernel.org>,
	<tzimmermann@suse.de>, <airlied@gmail.com>, <daniel@ffwll.ch>,
	<intel-xe@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>,
	<linux-kernel@vger.kernel.org>, Jani Nikula <jani.nikula@linux.intel.com>
Subject: Re: [PATCH] drm/xe/display: Fix memleak in display initialization
Message-ID: <abko5y3n5mju6srjly257bpqlvjf5ie6h6snboaekxnfv5mu76@jjumdgev76ag>
References: <20240125063633.989944-1-xiaoming.wang@intel.com>
 <20240126153453.997855-1-xiaoming.wang@intel.com>
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+Jani

On Fri, Jan 26, 2024 at 11:34:53PM +0800, wangxiaoming321 wrote:
>intel_power_domains_init has been called twice in xe_device_probe:
>xe_device_probe -> xe_display_init_nommio -> intel_power_domains_init(xe)
>xe_device_probe -> xe_display_init_noirq -> intel_display_driver_probe_noirq
>-> intel_power_domains_init(i915)

ok, once upon a time intel_power_domains_init() was called by the driver
initialization code and not initialized inside the display. I think.
Now it's part of the display probe and we never updated the xe side.

>
>It needs remove one to avoid power_domains->power_wells double malloc.
>
>unreferenced object 0xffff88811150ee00 (size 512):
>  comm "systemd-udevd", pid 506, jiffies 4294674198 (age 3605.560s)
>  hex dump (first 32 bytes):
>    10 b4 9d a0 ff ff ff ff ff ff ff ff ff ff ff ff  ................
>    ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 00  ................
>  backtrace:
>    [<ffffffff8134b901>] __kmem_cache_alloc_node+0x1c1/0x2b0
>    [<ffffffff812c98b2>] __kmalloc+0x52/0x150
>    [<ffffffffa08b0033>] __set_power_wells+0xc3/0x360 [xe]
>    [<ffffffffa08562fc>] xe_display_init_nommio+0x4c/0x70 [xe]
>    [<ffffffffa07f0d1c>] xe_device_probe+0x3c/0x5a0 [xe]
>    [<ffffffffa082e48f>] xe_pci_probe+0x33f/0x5a0 [xe]
>    [<ffffffff817f2187>] local_pci_probe+0x47/0xa0
>    [<ffffffff817f3db3>] pci_device_probe+0xc3/0x1f0
>    [<ffffffff8192f2a2>] really_probe+0x1a2/0x410
>    [<ffffffff8192f598>] __driver_probe_device+0x78/0x160
>    [<ffffffff8192f6ae>] driver_probe_device+0x1e/0x90
>    [<ffffffff8192f92a>] __driver_attach+0xda/0x1d0
>    [<ffffffff8192c95c>] bus_for_each_dev+0x7c/0xd0
>    [<ffffffff8192e159>] bus_add_driver+0x119/0x220
>    [<ffffffff81930d00>] driver_register+0x60/0x120
>    [<ffffffffa05e50a0>] 0xffffffffa05e50a0
>

This will need a Fixes trailer.  This seems to be a suitable one:

Fixes: 44e694958b95 ("drm/xe/display: Implement display support")

>Signed-off-by: wangxiaoming321 <xiaoming.wang@intel.com>
>---
> drivers/gpu/drm/xe/xe_display.c | 6 ------
> 1 file changed, 6 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_display.c b/drivers/gpu/drm/xe/xe_display.c
>index 74391d9b11ae..e4db069f0db3 100644
>--- a/drivers/gpu/drm/xe/xe_display.c
>+++ b/drivers/gpu/drm/xe/xe_display.c
>@@ -134,8 +134,6 @@ static void xe_display_fini_nommio(struct drm_device *dev, void *dummy)
>
> int xe_display_init_nommio(struct xe_device *xe)
> {
>-	int err;
>-
> 	if (!xe->info.enable_display)
> 		return 0;
>
>@@ -145,10 +143,6 @@ int xe_display_init_nommio(struct xe_device *xe)
> 	/* This must be called before any calls to HAS_PCH_* */
> 	intel_detect_pch(xe);
>
>-	err = intel_power_domains_init(xe);
>-	if (err)
>-		return err;

xe_display_init_nommio() has xe_display_fini_nommio() as its destructor
counter part. Unfortunately display side looks wrong as it does:

init:
	intel_display_driver_probe_noirq() -> intel_power_domains_init()

destroy:
	i915_driver_late_release() -> intel_power_domains_cleanup()

I think leaving intel_power_domains_cleanup() as is for now so it's
called by xe works, but this needs to go through CI, which apparently
this series didn't go. I re-triggered it.

+Jani if he thinks this can be changed in another way or already have
the complete solution.

Lucas De Marchi