Tracebacks in -next due to 'of: fix of_node leak caused in of_find_node_opts_by_path'

Tracebacks in -next due to 'of: fix of_node leak caused in of_find_node_opts_by_path'

[Guenter Roeck]

Hi,

I see a number of tracebacks in test runs on qemu-next, all related to omap
configurations.

Here is an example:

[    0.000000] OF: ERROR: Bad of_node_put() on /ocp@68000000
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W 4.10.0-rc7-next-20170210 #1
[    0.000000] Hardware name: Generic OMAP3-GP (Flattened Device Tree)
[    0.000000] [<c0310604>] (unwind_backtrace) from [<c030bbf4>] (show_stack+0x10/0x14)
[    0.000000] [<c030bbf4>] (show_stack) from [<c05add8c>] (dump_stack+0x98/0xac)
[    0.000000] [<c05add8c>] (dump_stack) from [<c05af1b0>] (kobject_release+0x48/0x7c)
[    0.000000] [<c05af1b0>] (kobject_release) from [<c0ad6138>] (__of_translate_address+0xb0/0x2cc)
[    0.000000] [<c0ad6138>] (__of_translate_address) from [<c0ad6388>] (__of_address_to_resource+0x28/0xb4)
[    0.000000] [<c0ad6388>] (__of_address_to_resource) from [<c0ad66f8>] (of_address_to_resource+0x70/0x80)
[    0.000000] [<c0ad66f8>] (of_address_to_resource) from [<c08485bc>] (of_syscon_register+0x88/0x22c)
[    0.000000] [<c08485bc>] (of_syscon_register) from [<c08487f0>] (syscon_node_to_regmap+0x90/0x94)
[    0.000000] [<c08487f0>] (syscon_node_to_regmap) from [<c1210184>] (omap_control_init+0x50/0xd8)
[    0.000000] [<c1210184>] (omap_control_init) from [<c1210010>] (omap_clk_init+0x3c/0x70)
[    0.000000] [<c1210010>] (omap_clk_init) from [<c1210a14>] (__omap_sync32k_timer_init+0x20/0x2b4)
[    0.000000] [<c1210a14>] (__omap_sync32k_timer_init) from [<c1210f24>] (omap3_secure_sync32k_timer_init+0x3c/0x48)
[    0.000000] [<c1210f24>] (omap3_secure_sync32k_timer_init) from [<c1200b24>] (start_kernel+0x244/0x38c)
[    0.000000] [<c1200b24>] (start_kernel) from [<8020807c>] (0x8020807c)
[    0.000000] Clocking rate (Crystal/Core/MPU): 26.0/332/500 MHz

There are several such messages with different call paths.

A log with all tracebacks is available at
http://kerneltests.org/builders/qemu-arm-next/builds/627/steps/qemubuildcommand/logs/stdio

Bisect points to commit 'of: fix of_node leak caused in
of_find_node_opts_by_path'. Bisect log is attached.

It is going to be interesting to learn if the patch introduces a problem
or if it exposes one.

Guenter

---
# bad: [632571b1bee00494aef749512d9f3290dfba0ead] Add linux-next specific files for 20170210
# good: [d5adbfcd5f7bcc6fa58a41c5c5ada0e5c826ce2c] Linux 4.10-rc7
git bisect start 'HEAD' 'v4.10-rc7'
# good: [0bd52e1bdcb050ad5bef5d8e93838d40fd44ac4b] Merge remote-tracking branch 'crypto/master'
git bisect good 0bd52e1bdcb050ad5bef5d8e93838d40fd44ac4b
# bad: [6431424e2adf1b48333f7bd54cd5be8fef3953d7] Merge remote-tracking branch 'tip/auto-latest'
git bisect bad 6431424e2adf1b48333f7bd54cd5be8fef3953d7
# good: [37f0c524925ae1f8fb62e39b3330357b1dc090bf] Merge remote-tracking branch 'sound/for-next'
git bisect good 37f0c524925ae1f8fb62e39b3330357b1dc090bf
# good: [18e1b83f8219ccc8051e80384f90682739bf19c4] Merge remote-tracking branch 'mfd/for-mfd-next'
git bisect good 18e1b83f8219ccc8051e80384f90682739bf19c4
# good: [7b844fd09215b87ed67ad69a3a5e09858f761dbb] Merge remote-tracking branch 'iommu/next'
git bisect good 7b844fd09215b87ed67ad69a3a5e09858f761dbb
# good: [11e891d2e00d4c9408c8a35712538d1003e3f549] Merge branch 'sched/core'
git bisect good 11e891d2e00d4c9408c8a35712538d1003e3f549
# bad: [059a17407b8136363594f1d8c9fa53ac6ca6ac2a] Merge remote-tracking branch 'spi/for-next'
git bisect bad 059a17407b8136363594f1d8c9fa53ac6ca6ac2a
# good: [9cfda694080954aa2be700ccadcedd0c5c15277a] Merge remote-tracking branches 'spi/topic/mpc52xx', 'spi/topic/ppc4xx', 'spi/topic/pxa2xx', 'spi/topic/rockchip' and 'spi/topic/rspi' into spi-next
git bisect good 9cfda694080954aa2be700ccadcedd0c5c15277a
# good: [4b741bc35962ccf93b798a233512850c48c2646e] dt-bindings: net: remove reference to fixed link support
git bisect good 4b741bc35962ccf93b798a233512850c48c2646e
# good: [6160be71baba3dd80501c90ab44e0f17d5854721] Merge remote-tracking branches 'spi/topic/s3c64xx', 'spi/topic/sh-msiof', 'spi/topic/slave' and 'spi/topic/topcliff-pch' into spi-next
git bisect good 6160be71baba3dd80501c90ab44e0f17d5854721
# good: [2a9bcff7f0d3883f5381f0fd8232990013002f92] Merge remote-tracking branch 'audit/next'
git bisect good 2a9bcff7f0d3883f5381f0fd8232990013002f92
# bad: [e553f539f2af39db5e3b2c273cc1a22d34be49ad] of: make of_device_make_bus_id() static
git bisect bad e553f539f2af39db5e3b2c273cc1a22d34be49ad
# bad: [0549bde0fcb11a95773e7dc4121738b9e653abf4] of: fix of_node leak caused in of_find_node_opts_by_path
git bisect bad 0549bde0fcb11a95773e7dc4121738b9e653abf4
# first bad commit: [0549bde0fcb11a95773e7dc4121738b9e653abf4] of: fix of_node leak caused in of_find_node_opts_by_path

Re: Tracebacks in -next due to 'of: fix of_node leak caused in of_find_node_opts_by_path'

[Guenter Roeck]

On Fri, Feb 10, 2017 at 05:29:47PM -0800, Guenter Roeck wrote:
> Hi,
> 
> I see a number of tracebacks in test runs on qemu-next, all related to omap
> configurations.
> 
> Here is an example:
> 
> [    0.000000] OF: ERROR: Bad of_node_put() on /ocp@68000000
> [    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W 4.10.0-rc7-next-20170210 #1
> [    0.000000] Hardware name: Generic OMAP3-GP (Flattened Device Tree)
> [    0.000000] [<c0310604>] (unwind_backtrace) from [<c030bbf4>] (show_stack+0x10/0x14)
> [    0.000000] [<c030bbf4>] (show_stack) from [<c05add8c>] (dump_stack+0x98/0xac)
> [    0.000000] [<c05add8c>] (dump_stack) from [<c05af1b0>] (kobject_release+0x48/0x7c)
> [    0.000000] [<c05af1b0>] (kobject_release) from [<c0ad6138>] (__of_translate_address+0xb0/0x2cc)
> [    0.000000] [<c0ad6138>] (__of_translate_address) from [<c0ad6388>] (__of_address_to_resource+0x28/0xb4)
> [    0.000000] [<c0ad6388>] (__of_address_to_resource) from [<c0ad66f8>] (of_address_to_resource+0x70/0x80)
> [    0.000000] [<c0ad66f8>] (of_address_to_resource) from [<c08485bc>] (of_syscon_register+0x88/0x22c)
> [    0.000000] [<c08485bc>] (of_syscon_register) from [<c08487f0>] (syscon_node_to_regmap+0x90/0x94)
> [    0.000000] [<c08487f0>] (syscon_node_to_regmap) from [<c1210184>] (omap_control_init+0x50/0xd8)
> [    0.000000] [<c1210184>] (omap_control_init) from [<c1210010>] (omap_clk_init+0x3c/0x70)
> [    0.000000] [<c1210010>] (omap_clk_init) from [<c1210a14>] (__omap_sync32k_timer_init+0x20/0x2b4)
> [    0.000000] [<c1210a14>] (__omap_sync32k_timer_init) from [<c1210f24>] (omap3_secure_sync32k_timer_init+0x3c/0x48)
> [    0.000000] [<c1210f24>] (omap3_secure_sync32k_timer_init) from [<c1200b24>] (start_kernel+0x244/0x38c)
> [    0.000000] [<c1200b24>] (start_kernel) from [<8020807c>] (0x8020807c)
> [    0.000000] Clocking rate (Crystal/Core/MPU): 26.0/332/500 MHz
> 
> There are several such messages with different call paths.
> 
> A log with all tracebacks is available at
> http://kerneltests.org/builders/qemu-arm-next/builds/627/steps/qemubuildcommand/logs/stdio
> 
> Bisect points to commit 'of: fix of_node leak caused in
> of_find_node_opts_by_path'. Bisect log is attached.
> 
> It is going to be interesting to learn if the patch introduces a problem
> or if it exposes one.
> 
It exposes a problem. omap3xxx_hwmod_is_hs_ip_block_usable() calls
of_find_node_by_name(bus, ...), which releases 'bus'. The function
is called multiple times with the same 'bus' node, meaning 'bus' is
released multiple times.

There are other instances of the same problem, such as in leon_init_timers()
or _qcom_cc_register_board_clk(). I'll see if I can submit some patches.

Guenter
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