Hi Thierry,

On 21/01/2015 11:50, Thierry Reding wrote:

On Wed, Jan 21, 2015 at 12:03:41AM +0000, Paul Walmsley wrote:

quoted

(linux-ide@ added)

Commit c7d7ddee7e24eedde6149eefbcfbfbc7125b9ff0 ("ata: libahci: Allow
using multiple regulators") in Linux-next 20150120 causes a panic
during boot on multiple Tegra boards:

http://nvt.pwsan.com/experimental/linux-next/testlogs/test_next-20150120/20150120001539/boot/tegra30-beaver/tegra30-beaver/tegra_defconfig_log.txt
http://nvt.pwsan.com/experimental/linux-next/testlogs/test_next-20150120/20150120001539/boot/tegra114-dalmore-a04/tegra114-dalmore/tegra_defconfig_log.txt
http://nvt.pwsan.com/experimental/linux-next/testlogs/test_next-20150120/20150120001539/boot/tegra124-jetson-tk1/tegra124-jetson-tk1/tegra_defconfig_log.txt

Taking the latter boot log as an example, the 6b6b6b9f value that the 
kernel is trying to dereference is being passed into _regulator_put() as a 
struct regulator *.


- Paul

Here's the devres log of what's happening:

	[    4.949689] tegra-ahci 70027000.sata: DEVRES ADD ee1e2a00 devm_kzalloc_release (16 bytes)
	[    4.957886] tegra-ahci 70027000.sata: DEVRES ADD ee1e29c0 devm_pinctrl_release (4 bytes)
	[    4.965984] tegra-ahci 70027000.sata: DEVRES REM ee1e29c0 devm_pinctrl_release (4 bytes)
	[    4.974079] tegra-ahci 70027000.sata: DEVRES REM ee1e2a00 devm_kzalloc_release (16 bytes)
	[    4.982298] tegra-ahci 70027000.sata: DEVRES ADD ee1e29c0 grp< (0 bytes)
	[    4.989006] tegra-ahci 70027000.sata: DEVRES ADD ee1dae00 ahci_platform_put_resources (96 bytes)
	[    4.997784] tegra-ahci 70027000.sata: DEVRES ADD ee1e2980 devm_region_release (12 bytes)
	[    5.005879] tegra-ahci 70027000.sata: DEVRES ADD ee1e2900 devm_ioremap_release (4 bytes)
	[    5.014005] tegra-ahci 70027000.sata: DEVRES ADD ee1e28c0 devm_kzalloc_release (4 bytes)
	[    5.022096] tegra-ahci 70027000.sata: DEVRES ADD ee1e2880 devm_kzalloc_release (4 bytes)
	[    5.030209] tegra-ahci 70027000.sata: DEVRES ADD ee1e2840 devm_phy_release (4 bytes)
	[    5.037952] tegra-ahci 70027000.sata: DEVRES REM ee1e29c0 grp< (0 bytes)
	[    5.044660] tegra-ahci 70027000.sata: DEVRES ADD ee1dad80 devm_kzalloc_release (84 bytes)
	[    5.052845] tegra-ahci 70027000.sata: DEVRES ADD ee1e29c0 devm_region_release (12 bytes)
	[    5.060938] tegra-ahci 70027000.sata: DEVRES ADD ee1e2f80 devm_ioremap_release (4 bytes)
	[    5.069039] tegra-ahci 70027000.sata: DEVRES ADD ee1e2f40 devm_reset_control_release (4 bytes)
	[    5.077647] tegra-ahci 70027000.sata: DEVRES ADD ee1e2ec0 devm_reset_control_release (4 bytes)
	[    5.086271] tegra-ahci 70027000.sata: DEVRES ADD ee1e2e40 devm_reset_control_release (4 bytes)
	[    5.094890] tegra-ahci 70027000.sata: DEVRES ADD ee1e2dc0 devm_clk_release (4 bytes)
	[    5.102659] tegra-ahci 70027000.sata: Failed to get supply 'avdd': -517
	[    5.109276] tegra-ahci 70027000.sata: Failed to get regulators
	[    5.115103] tegra-ahci 70027000.sata: DEVRES REL ee1e2dc0 devm_clk_release (4 bytes)
	[    5.122850] tegra-ahci 70027000.sata: DEVRES REL ee1e2e40 devm_reset_control_release (4 bytes)
	[    5.131462] tegra-ahci 70027000.sata: DEVRES REL ee1e2ec0 devm_reset_control_release (4 bytes)
	[    5.140073] tegra-ahci 70027000.sata: DEVRES REL ee1e2f40 devm_reset_control_release (4 bytes)
	[    5.148672] tegra-ahci 70027000.sata: DEVRES REL ee1e2f80 devm_ioremap_release (4 bytes)
	[    5.156764] tegra-ahci 70027000.sata: DEVRES REL ee1e29c0 devm_region_release (12 bytes)
	[    5.164856] tegra-ahci 70027000.sata: DEVRES REL ee1dad80 devm_kzalloc_release (84 bytes)
	[    5.173034] tegra-ahci 70027000.sata: DEVRES REL ee1e2840 devm_phy_release (4 bytes)
	[    5.180778] tegra-ahci 70027000.sata: DEVRES REL ee1e2880 devm_kzalloc_release (4 bytes)
	[    5.188868] tegra-ahci 70027000.sata: DEVRES REL ee1e28c0 devm_kzalloc_release (4 bytes)
	[    5.196948] tegra-ahci 70027000.sata: DEVRES REL ee1e2900 devm_ioremap_release (4 bytes)
	[    5.205037] tegra-ahci 70027000.sata: DEVRES REL ee1e2980 devm_region_release (12 bytes)
	[    5.213129] tegra-ahci 70027000.sata: DEVRES REL ee1dae00 ahci_platform_put_resources (96 bytes)

What's happening here is that ahci_platform_put_resources() is added to
the devres list before the devm_kzalloc() that allocates the target_pwrs
array, which causes the target_pwrs array to be freed before devres gets
to call ahci_platform_put_resources().

Mixing managed and non-managed resources this way doesn't work, so I had
to apply the attached patch to fix this.

Tejun, preferably the attached patch should be squashed into commit
c7d7ddee7e24 ("ata: libahci: Allow using multiple regulators") to avoid
breaking bisectability. If you don't want to rewrite history, let me
know and I can turn it into a proper patch.

Thanks having took care of it. I tested your patch and it didn't introduce
any regression on the board I tested.

Gregory


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com