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SubjectRe: [PATCH] acpi: osl: Replace GFP_ATOMIC with GFP_KERNEL in acpi_os_execute
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On 2018/2/8 18:20, Rafael J. Wysocki wrote:
> On Thursday, February 8, 2018 11:13:10 AM CET Chris Wilson wrote:
>> Quoting Rafael J. Wysocki (2018-02-08 09:51:41)
>>> On Thursday, January 25, 2018 11:13:41 AM CET Jia-Ju Bai wrote:
>>>> After checking all possible call chains to acpi_os_execute here,
>>>> my tool finds that acpi_os_execute is never called in atomic context.
>>>> And acpi_os_execute calls acpi_debugger_create_thread
>>>> which calls mutex_lock,
>>>> thus it proves again that acpi_os_execute can
>>>> call functions which may sleep.
>>>> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
>>>>
>>>> This is found by a static analysis tool named DCNS written by myself.
>>>>
>>>> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
>>>> ---
>>>> drivers/acpi/osl.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>>>> index 3bb46cb..8ee605e 100644
>>>> --- a/drivers/acpi/osl.c
>>>> +++ b/drivers/acpi/osl.c
>>>> @@ -1066,7 +1066,7 @@ acpi_status acpi_os_execute(acpi_execute_type type,
>>>> * having a static work_struct.
>>>> */
>>>>
>>>> - dpc = kzalloc(sizeof(struct acpi_os_dpc), GFP_ATOMIC);
>>>> + dpc = kzalloc(sizeof(struct acpi_os_dpc), GFP_KERNEL);
>>>> if (!dpc)
>>>> return AE_NO_MEMORY;
>>>>
>>>>
>>> Applied, thanks!
>> Hmm, not this patch per se, but
>>
>> https://intel-gfx-ci.01.org/tree/next/next-20180207/fi-bxt-dsi/dmesg0.log
>> [ 111.378236] BUG: sleeping function called from invalid context at mm/slab.h:420
>> [ 111.378259] in_atomic(): 1, irqs_disabled(): 1, pid: 1701, name: gem_exec_flush
>> [ 111.378275] INFO: lockdep is turned off.
>> [ 111.378277] irq event stamp: 0
>> [ 111.378280] hardirqs last enabled at (0): [< (null)>] (null)
>> [ 111.378286] hardirqs last disabled at (0): [<00000000a01fa473>] copy_process.part.7+0x2f1/0x1db0
>> [ 111.378290] softirqs last enabled at (0): [<00000000a01fa473>] copy_process.part.7+0x2f1/0x1db0
>> [ 111.378292] softirqs last disabled at (0): [< (null)>] (null)
>> [ 111.378293] Preemption disabled at:
>> [ 111.378298] [<ffffffffa18f14f6>] __mutex_lock+0x56/0x9b0
>> [ 111.378311] CPU: 1 PID: 1701 Comm: gem_exec_flush Tainted: G U W 4.15.0-next-20180207-g5d1c98967100-next-20180207 #1
>> [ 111.378313] Hardware name: Intel Corp. Broxton P/Apollolake RVP1A, BIOS APLKRVPA.X64.0150.B11.1608081044 08/08/2016
>> [ 111.378314] Call Trace:
>> [ 111.378318] <IRQ>
>> [ 111.378323] dump_stack+0x5f/0x86
>> [ 111.378328] ___might_sleep+0x1d9/0x240
>> [ 111.378334] ? acpi_os_execute+0x2d/0x130
>> [ 111.378338] kmem_cache_alloc_trace+0x1ae/0x2b0
>> [ 111.378344] ? acpi_ev_asynch_enable_gpe+0x2d/0x2d
>> [ 111.378347] acpi_os_execute+0x2d/0x130
>> [ 111.378351] acpi_ev_gpe_dispatch+0xd7/0x120
>> [ 111.378355] acpi_ev_gpe_detect+0x156/0x195
>> [ 111.378362] acpi_ev_sci_xrupt_handler+0x16/0x28
>> [ 111.378365] acpi_irq+0xd/0x30
>> [ 111.378369] __handle_irq_event_percpu+0x3c/0x340
>> [ 111.378374] handle_irq_event_percpu+0x1b/0x50
>> [ 111.378378] handle_irq_event+0x2f/0x50
>> [ 111.378381] handle_fasteoi_irq+0x93/0x150
>> [ 111.378386] handle_irq+0x11/0x20
>> [ 111.378390] do_IRQ+0x5e/0x120
>> [ 111.378395] common_interrupt+0xbb/0xbb
>> [ 111.378397] </IRQ>
>>
>> does tell us that acpi_os_execute() is called in irq context.
> Well, right, thanks!
>
> I overlooked this instance, so dropping the patch.

Sorry for my false positive.
My tool missed that acpi_ev_sci_xrupt_handler() is an interrupt handler,
sorry.
Thank Chris for testing my patch.


Best wishes,
Jia-Ju Bai

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