[Bug 214425] New: [drm][amdgpu][TTM] Page pool memory never gets freed

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=214425

            Bug ID: 214425
           Summary: [drm][amdgpu][TTM] Page pool memory never gets freed
           Product: Drivers
           Version: 2.5
    Kernel Version: 5.14.3
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - non Intel)
          Assignee: drivers_video-dri at kernel-bugs.osdl.org
          Reporter: doucha at swarmtech.cz
        Regression: No

Hello,
while playing certain webGL games, I've noticed what appears to be a memory
leak in the kernel. Further investigation revealed that after about an hour of
gameplay, over 3GB of memory (half of all available RAM on my machine) will be
taken by the TTM page pool.

While the excessive allocation may be caused by a resource leak in the game
itself (I need to investigate that further), the larger problem is that TTM
never releases the memory even after I quit the game. Closing the game only
moves the allocated memory from active buffer objects to idle memory pool where
it'll get stuck until I reboot the system. Shutting down X server doesn't
release the memory either.

System specs:
HP Probook 455 G7
AMD Ryzen 5 4500U CPU
AMD Renoir GPU (Mesa 21.2.1, LLVM 12.0)
Gentoo Linux

TTM statistics before quitting the game:
/sys/kernel/debug/ttm/buffer_objects:
3116

/sys/kernel/debug/ttm/page_pool:
          --- 0--- --- 1--- --- 2--- --- 3--- --- 4--- --- 5--- --- 6--- ---
7--- --- 8--- --- 9--- ---10---
wc      :        2        2        1        1        8        2        0       
1        2        1        2
uc      :        0        0        0        0        0        0        0       
0        0        0        0
wc 32   :        0        0        0        0        0        0        0       
0        0        0        0
uc 32   :        0        0        0        0        0        0        0       
0        0        0        0

total   :     3410 of   939433

/sys/kernel/debug/ttm/page_pool_shrink:
2898/512


=======================================

TTM statistics after quitting the game (until reboot):
/sys/kernel/debug/ttm/buffer_objects:
403

/sys/kernel/debug/ttm/page_pool:
          --- 0--- --- 1--- --- 2--- --- 3--- --- 4--- --- 5--- --- 6--- ---
7--- --- 8--- --- 9--- ---10---
wc      :      151      134       20        5      255      241      790     
193      416     1121       83
uc      :        0        0        0        0        0        0        0       
0        0        0        0
wc 32   :        0        0        0        0        0        0        0       
0        0        0        0
uc 32   :        0        0        0        0        0        0        0       
0        0        0        0

total   :   853035 of   939433

/sys/kernel/debug/ttm/page_pool_shrink:
853034/1

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