When the test 'CONFIG_DEBUG_TEST_DRIVER_REMOVE=y' is enabled,
arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init).
devtmpfs gets killed because we try to remove a file and decrement the
wb reference count before the noop_backing_device_info gets initialized.
[ 0.332075] Serial: AMBA PL011 UART driver
[ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1
[ 0.502382] console [ttyAMA0] enabled
[ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000
[ 0.516053] Mem abort info:
[ 0.516222] ESR = 0x96000004
[ 0.516417] Exception class = DABT (current EL), IL = 32 bits
[ 0.516641] SET = 0, FnV = 0
[ 0.516826] EA = 0, S1PTW = 0
[ 0.516984] Data abort info:
[ 0.517149] ISV = 0, ISS = 0x00000004
[ 0.517339] CM = 0, WnR = 0
[ 0.517553] [0000800074c12000] user address but active_mm is swapper
[ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 0.518305] Modules linked in:
[ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82
[ 0.519307] Hardware name: linux,dummy-virt (DT)
[ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 0.519959] pc : __destroy_inode+0x94/0x2a8
[ 0.520212] lr : __destroy_inode+0x78/0x2a8
[ 0.520401] sp : ffff0000098c3b20
[ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714
[ 0.520904] x27: 0000000000002000 x26: 0000000000002000
[ 0.521179] x25: ffff000009583000 x24: 0000000000000000
[ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0
[ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000
[ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400
[ 0.522376] x17: 0000000000000000 x16: 0000000000000000
[ 0.522727] x15: 0000000000000400 x14: 0000000000000400
[ 0.523068] x13: 0000000000000001 x12: 0000000000000001
[ 0.523421] x11: 0000000000000000 x10: 0000000000000970
[ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190
[ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88
[ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb
[ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff
[ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000
[ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____))
[ 0.525529] Call trace:
[ 0.525806] __destroy_inode+0x94/0x2a8
[ 0.526108] destroy_inode+0x34/0x88
[ 0.526370] evict+0x144/0x1c8
[ 0.526636] iput+0x184/0x230
[ 0.526871] dentry_unlink_inode+0x118/0x130
[ 0.527152] d_delete+0xd8/0xe0
[ 0.527420] vfs_unlink+0x240/0x270
[ 0.527665] handle_remove+0x1d8/0x330
[ 0.527875] devtmpfsd+0x138/0x1c8
[ 0.528085] kthread+0x14c/0x158
[ 0.528291] ret_from_fork+0x10/0x18
[ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04)
[ 0.529367] ---[ end trace 5a3dee47727f877c ]---
Rework to set suppress_bind_attrs flag to avoid removing the device when
CONFIG_DEBUG_TEST_DRIVER_REMOVE=y. This applies for pic32_uart and
xilinx_uartps as well.
Cc: Arnd Bergmann <[email protected]>
Co-developed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Anders Roxell <[email protected]>
---
drivers/tty/serial/amba-pl011.c | 2 ++
drivers/tty/serial/pic32_uart.c | 1 +
drivers/tty/serial/xilinx_uartps.c | 1 +
3 files changed, 4 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index ebd33c0232e6..89ade213a1a9 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2780,6 +2780,7 @@ static struct platform_driver arm_sbsa_uart_platform_driver = {
.name = "sbsa-uart",
.of_match_table = of_match_ptr(sbsa_uart_of_match),
.acpi_match_table = ACPI_PTR(sbsa_uart_acpi_match),
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011),
},
};
@@ -2808,6 +2809,7 @@ static struct amba_driver pl011_driver = {
.drv = {
.name = "uart-pl011",
.pm = &pl011_dev_pm_ops,
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_AMBA_PL011),
},
.id_table = pl011_ids,
.probe = pl011_probe,
diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
index fd80d999308d..0bdf1687983f 100644
--- a/drivers/tty/serial/pic32_uart.c
+++ b/drivers/tty/serial/pic32_uart.c
@@ -919,6 +919,7 @@ static struct platform_driver pic32_uart_platform_driver = {
.driver = {
.name = PIC32_DEV_NAME,
.of_match_table = of_match_ptr(pic32_serial_dt_ids),
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_PIC32),
},
};
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 0e3dae461f71..806a953ac8d4 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1717,6 +1717,7 @@ static struct platform_driver cdns_uart_platform_driver = {
.name = CDNS_UART_NAME,
.of_match_table = cdns_uart_of_match,
.pm = &cdns_uart_dev_pm_ops,
+ .suppress_bind_attrs = IS_BUILTIN(CONFIG_SERIAL_XILINX_PS_UART),
},
};
--
2.19.1
When enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE devtmpfs gets killed
because we try to remove a file and decrement the wb reference count
before the noop_backing_device_info gets initialized.
Since arch_initcall(pl011_init) came before
subsys_initcall(default_bdi_init), devtmpfs' handle_remove() crashes
because the reference count is a NULL pointer only because bdi->wb
hasn't been initialized yet.
[ 0.332075] Serial: AMBA PL011 UART driver
[ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1
[ 0.502382] console [ttyAMA0] enabled
[ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000
[ 0.516053] Mem abort info:
[ 0.516222] ESR = 0x96000004
[ 0.516417] Exception class = DABT (current EL), IL = 32 bits
[ 0.516641] SET = 0, FnV = 0
[ 0.516826] EA = 0, S1PTW = 0
[ 0.516984] Data abort info:
[ 0.517149] ISV = 0, ISS = 0x00000004
[ 0.517339] CM = 0, WnR = 0
[ 0.517553] [0000800074c12000] user address but active_mm is swapper
[ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 0.518305] Modules linked in:
[ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82
[ 0.519307] Hardware name: linux,dummy-virt (DT)
[ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 0.519959] pc : __destroy_inode+0x94/0x2a8
[ 0.520212] lr : __destroy_inode+0x78/0x2a8
[ 0.520401] sp : ffff0000098c3b20
[ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714
[ 0.520904] x27: 0000000000002000 x26: 0000000000002000
[ 0.521179] x25: ffff000009583000 x24: 0000000000000000
[ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0
[ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000
[ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400
[ 0.522376] x17: 0000000000000000 x16: 0000000000000000
[ 0.522727] x15: 0000000000000400 x14: 0000000000000400
[ 0.523068] x13: 0000000000000001 x12: 0000000000000001
[ 0.523421] x11: 0000000000000000 x10: 0000000000000970
[ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190
[ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88
[ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb
[ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff
[ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000
[ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____))
[ 0.525529] Call trace:
[ 0.525806] __destroy_inode+0x94/0x2a8
[ 0.526108] destroy_inode+0x34/0x88
[ 0.526370] evict+0x144/0x1c8
[ 0.526636] iput+0x184/0x230
[ 0.526871] dentry_unlink_inode+0x118/0x130
[ 0.527152] d_delete+0xd8/0xe0
[ 0.527420] vfs_unlink+0x240/0x270
[ 0.527665] handle_remove+0x1d8/0x330
[ 0.527875] devtmpfsd+0x138/0x1c8
[ 0.528085] kthread+0x14c/0x158
[ 0.528291] ret_from_fork+0x10/0x18
[ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04)
[ 0.529367] ---[ end trace 5a3dee47727f877c ]---
Rework so that wb_put have an extra check if wb->bdi before decrement
wb->refcnt and also add a WARN_ON to get a warning if it happens again
in other drivers.
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Cc: Arnd Bergmann <[email protected]>
Co-developed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Anders Roxell <[email protected]>
---
include/linux/backing-dev-defs.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 9a6bc0951cfa..20721550d32a 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -258,7 +258,7 @@ static inline void wb_get(struct bdi_writeback *wb)
*/
static inline void wb_put(struct bdi_writeback *wb)
{
- if (wb != &wb->bdi->wb)
+ if (!WARN_ON(!wb->bdi) && wb != &wb->bdi->wb)
percpu_ref_put(&wb->refcnt);
}
--
2.19.1
On Wed, 17 Oct 2018 16:03:10 +0200 Anders Roxell <[email protected]> wrote:
> Cc: Arnd Bergmann <[email protected]>
> Co-developed-by: Arnd Bergmann <[email protected]>
> Signed-off-by: Anders Roxell <[email protected]>
This should have Arnd's Signed-off-by: as well.
On Wed, 17 Oct 2018 16:03:11 +0200 Anders Roxell <[email protected]> wrote:
> When enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE devtmpfs gets killed
> because we try to remove a file and decrement the wb reference count
> before the noop_backing_device_info gets initialized.
>
> Since arch_initcall(pl011_init) came before
> subsys_initcall(default_bdi_init), devtmpfs' handle_remove() crashes
> because the reference count is a NULL pointer only because bdi->wb
> hasn't been initialized yet.
Is this changelog correct? What does drivers/tty/serial/amba-pl011.c
have to do with page writeback? Confused.
> [ 0.332075] Serial: AMBA PL011 UART driver
> [ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1
> [ 0.502382] console [ttyAMA0] enabled
> [ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000
> [ 0.516053] Mem abort info:
> [ 0.516222] ESR = 0x96000004
> [ 0.516417] Exception class = DABT (current EL), IL = 32 bits
> [ 0.516641] SET = 0, FnV = 0
> [ 0.516826] EA = 0, S1PTW = 0
> [ 0.516984] Data abort info:
> [ 0.517149] ISV = 0, ISS = 0x00000004
> [ 0.517339] CM = 0, WnR = 0
> [ 0.517553] [0000800074c12000] user address but active_mm is swapper
> [ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [ 0.518305] Modules linked in:
> [ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82
> [ 0.519307] Hardware name: linux,dummy-virt (DT)
> [ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO)
> [ 0.519959] pc : __destroy_inode+0x94/0x2a8
> [ 0.520212] lr : __destroy_inode+0x78/0x2a8
> [ 0.520401] sp : ffff0000098c3b20
> [ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714
> [ 0.520904] x27: 0000000000002000 x26: 0000000000002000
> [ 0.521179] x25: ffff000009583000 x24: 0000000000000000
> [ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0
> [ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000
> [ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400
> [ 0.522376] x17: 0000000000000000 x16: 0000000000000000
> [ 0.522727] x15: 0000000000000400 x14: 0000000000000400
> [ 0.523068] x13: 0000000000000001 x12: 0000000000000001
> [ 0.523421] x11: 0000000000000000 x10: 0000000000000970
> [ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190
> [ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88
> [ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb
> [ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff
> [ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000
> [ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____))
> [ 0.525529] Call trace:
> [ 0.525806] __destroy_inode+0x94/0x2a8
> [ 0.526108] destroy_inode+0x34/0x88
> [ 0.526370] evict+0x144/0x1c8
> [ 0.526636] iput+0x184/0x230
> [ 0.526871] dentry_unlink_inode+0x118/0x130
> [ 0.527152] d_delete+0xd8/0xe0
> [ 0.527420] vfs_unlink+0x240/0x270
> [ 0.527665] handle_remove+0x1d8/0x330
> [ 0.527875] devtmpfsd+0x138/0x1c8
> [ 0.528085] kthread+0x14c/0x158
> [ 0.528291] ret_from_fork+0x10/0x18
> [ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04)
Seems that there is indeed some form of linkage. Can this be spelled
out more in the changelog please?
>
> Rework so that wb_put have an extra check if wb->bdi before decrement
> wb->refcnt and also add a WARN_ON to get a warning if it happens again
> in other drivers.
>
> Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
> Cc: Arnd Bergmann <[email protected]>
> Co-developed-by: Arnd Bergmann <[email protected]>
> Signed-off-by: Anders Roxell <[email protected]>
Signed-off-by: Arnd, please.
> --- a/include/linux/backing-dev-defs.h
> +++ b/include/linux/backing-dev-defs.h
> @@ -258,7 +258,7 @@ static inline void wb_get(struct bdi_writeback *wb)
> */
> static inline void wb_put(struct bdi_writeback *wb)
> {
> - if (wb != &wb->bdi->wb)
> + if (!WARN_ON(!wb->bdi) && wb != &wb->bdi->wb)
> percpu_ref_put(&wb->refcnt);
> }
The !WARN_ON(!expr) isn't very easy to follow. This:
{
if (WARN_ON_ONCE(!wb->bdi)) {
/*
* Nice comment explaining how this situation comes about
*/
return;
}
if (wb != &wb->bdi->wb)
percpu_ref_put(&wb->refcnt);
}
is better, no?
Also, please note the s/WARN_ON/WARN_ON_ONCE/. I don't think we gain
anything from reporting the same thing many times?
On 10/17/2018 4:05 PM, Andrew Morton wrote:
> On Wed, 17 Oct 2018 16:03:10 +0200 Anders Roxell <[email protected]> wrote:
>
>> Cc: Arnd Bergmann <[email protected]>
>> Co-developed-by: Arnd Bergmann <[email protected]>
>> Signed-off-by: Anders Roxell <[email protected]>
>
> This should have Arnd's Signed-off-by: as well.
I'm just interested to know, why?
--
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
On Wed, 17 Oct 2018 16:21:08 -0600 Jeffrey Hugo <[email protected]> wrote:
> On 10/17/2018 4:05 PM, Andrew Morton wrote:
> > On Wed, 17 Oct 2018 16:03:10 +0200 Anders Roxell <[email protected]> wrote:
> >
> >> Cc: Arnd Bergmann <[email protected]>
> >> Co-developed-by: Arnd Bergmann <[email protected]>
> >> Signed-off-by: Anders Roxell <[email protected]>
> >
> > This should have Arnd's Signed-off-by: as well.
>
> I'm just interested to know, why?
So that Arnd certifies that
(a) The contribution was created in whole or in part by me and I
have the right to submit it under the open source license
indicated in the file; or
and all the other stuff in Documentation/process/submitting-patches.rst
section 11!
Also, because section 12 says so :) And that final sentence is, I
believe, appropriate.
On 10/17/2018 4:32 PM, Andrew Morton wrote:
> On Wed, 17 Oct 2018 16:21:08 -0600 Jeffrey Hugo <[email protected]> wrote:
>
>> On 10/17/2018 4:05 PM, Andrew Morton wrote:
>>> On Wed, 17 Oct 2018 16:03:10 +0200 Anders Roxell <[email protected]> wrote:
>>>
>>>> Cc: Arnd Bergmann <[email protected]>
>>>> Co-developed-by: Arnd Bergmann <[email protected]>
>>>> Signed-off-by: Anders Roxell <[email protected]>
>>>
>>> This should have Arnd's Signed-off-by: as well.
>>
>> I'm just interested to know, why?
>
> So that Arnd certifies that
>
> (a) The contribution was created in whole or in part by me and I
> have the right to submit it under the open source license
> indicated in the file; or
>
> and all the other stuff in Documentation/process/submitting-patches.rst
> section 11!
>
> Also, because section 12 says so :) And that final sentence is, I
> believe, appropriate.
Ah, interesting. I see that the documentation was updated since I was
told last year in the same situation by a different maintainer that
co-authors should not have SOB lines on the patch.
Good to know. Thanks for illuminating me.
--
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.