There is a memory leak which left some objects not freed. The reference counter of mapping: 'mapping->kref' was 2 when calling arm_iommu_detach_device(), so the release_iommu_mapping() won't be called. Since the old mapping structure is not going to be used any more (because it is detached and new one attached), call arm_iommu_release_mapping() to trigger cleanup.
Found using kmemleak detector, the output:
unreferenced object 0xc2137640 (size 64): comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s) hex dump (first 32 bytes): 50 a3 14 c2 80 a2 14 c2 01 00 00 00 20 00 00 00 P........... ... 00 10 00 00 00 80 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<3acd268d>] arch_setup_dma_ops+0x4c/0x104 [<9f7d2cce>] of_dma_configure+0x19c/0x3a4 [<ba07704b>] really_probe+0xb0/0x47c [<4f510e4f>] driver_probe_device+0x78/0x1c4 [<7481a0cf>] device_driver_attach+0x58/0x60 [<0ff8f5c1>] __driver_attach+0xb8/0x158 [<86006144>] bus_for_each_dev+0x74/0xb4 [<10159dca>] bus_add_driver+0x1c0/0x200 [<8a265265>] driver_register+0x74/0x108 [<e0f3451a>] exynos_drm_init+0xb0/0x134 [<db3fc7ba>] do_one_initcall+0x90/0x458 [<6da35917>] kernel_init_freeable+0x188/0x200 [<db3f74d4>] kernel_init+0x8/0x110 [<1f3cddf9>] ret_from_fork+0x14/0x20 [<8cd12507>] 0x0 unreferenced object 0xc214a280 (size 128): comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s) hex dump (first 32 bytes): 00 a0 ec ed 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<3acd268d>] arch_setup_dma_ops+0x4c/0x104 [<9f7d2cce>] of_dma_configure+0x19c/0x3a4 [<ba07704b>] really_probe+0xb0/0x47c [<4f510e4f>] driver_probe_device+0x78/0x1c4 [<7481a0cf>] device_driver_attach+0x58/0x60 [<0ff8f5c1>] __driver_attach+0xb8/0x158 [<86006144>] bus_for_each_dev+0x74/0xb4 [<10159dca>] bus_add_driver+0x1c0/0x200 [<8a265265>] driver_register+0x74/0x108 [<e0f3451a>] exynos_drm_init+0xb0/0x134 [<db3fc7ba>] do_one_initcall+0x90/0x458 [<6da35917>] kernel_init_freeable+0x188/0x200 [<db3f74d4>] kernel_init+0x8/0x110 [<1f3cddf9>] ret_from_fork+0x14/0x20 [<8cd12507>] 0x0 unreferenced object 0xedeca000 (size 4096): comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<3acd268d>] arch_setup_dma_ops+0x4c/0x104 [<9f7d2cce>] of_dma_configure+0x19c/0x3a4 [<ba07704b>] really_probe+0xb0/0x47c [<4f510e4f>] driver_probe_device+0x78/0x1c4 [<7481a0cf>] device_driver_attach+0x58/0x60 [<0ff8f5c1>] __driver_attach+0xb8/0x158 [<86006144>] bus_for_each_dev+0x74/0xb4 [<10159dca>] bus_add_driver+0x1c0/0x200 [<8a265265>] driver_register+0x74/0x108 [<e0f3451a>] exynos_drm_init+0xb0/0x134 [<db3fc7ba>] do_one_initcall+0x90/0x458 [<6da35917>] kernel_init_freeable+0x188/0x200 [<db3f74d4>] kernel_init+0x8/0x110 [<1f3cddf9>] ret_from_fork+0x14/0x20 [<8cd12507>] 0x0 unreferenced object 0xc214a300 (size 128): comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s) hex dump (first 32 bytes): 00 a3 14 c2 00 a3 14 c2 00 40 18 c2 00 80 18 c2 .........@...... 02 00 02 00 ad 4e ad de ff ff ff ff ff ff ff ff .....N.......... backtrace: [<08cbd8bc>] iommu_domain_alloc+0x24/0x50 [<b835abee>] arm_iommu_create_mapping+0xe4/0x134 [<3acd268d>] arch_setup_dma_ops+0x4c/0x104 [<9f7d2cce>] of_dma_configure+0x19c/0x3a4 [<ba07704b>] really_probe+0xb0/0x47c [<4f510e4f>] driver_probe_device+0x78/0x1c4 [<7481a0cf>] device_driver_attach+0x58/0x60 [<0ff8f5c1>] __driver_attach+0xb8/0x158 [<86006144>] bus_for_each_dev+0x74/0xb4 [<10159dca>] bus_add_driver+0x1c0/0x200 [<8a265265>] driver_register+0x74/0x108 [<e0f3451a>] exynos_drm_init+0xb0/0x134 [<db3fc7ba>] do_one_initcall+0x90/0x458 [<6da35917>] kernel_init_freeable+0x188/0x200 [<db3f74d4>] kernel_init+0x8/0x110 [<1f3cddf9>] ret_from_fork+0x14/0x20
Signed-off-by: Lukasz Luba lukasz.luba@arm.com ---
Hi all,
I have discovered this issue on OdroidXU4 while running some stress tests for upcoming Energy Model. To reproduce it, kernel must be compiled with DEBUG_KMEMLEAK. When the boot has finished, type: # echo scan > /sys/kernel/debug/kmemleak # cat /sys/kernel/debug/kmemleak You should expect similar output to the one from the commit message.
I don't know if it should go via stable tree as well. I can resend with CC stable, if there is a need.
Regards, Lukasz Luba
drivers/gpu/drm/exynos/exynos_drm_dma.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dma.c b/drivers/gpu/drm/exynos/exynos_drm_dma.c index 9ebc02768847..45f209ec107f 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_dma.c +++ b/drivers/gpu/drm/exynos/exynos_drm_dma.c @@ -74,8 +74,13 @@ static int drm_iommu_attach_device(struct drm_device *drm_dev, return ret;
if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) { - if (to_dma_iommu_mapping(subdrv_dev)) + struct dma_iommu_mapping *mapping = + to_dma_iommu_mapping(subdrv_dev); + + if (mapping) { arm_iommu_detach_device(subdrv_dev); + arm_iommu_release_mapping(mapping); + }
ret = arm_iommu_attach_device(subdrv_dev, priv->mapping); } else if (IS_ENABLED(CONFIG_IOMMU_DMA)) {