* Return value of __mm_populate
@ 2013-04-13 12:14 Marco Stornelli
2013-04-13 12:41 ` Marco
2013-04-14 0:18 ` KOSAKI Motohiro
0 siblings, 2 replies; 4+ messages in thread
From: Marco Stornelli @ 2013-04-13 12:14 UTC (permalink / raw)
To: linux-mm; +Cc: Linux FS Devel
Hi,
I was seeing the code of __mm_populate (in -next) and I've got a doubt
about the return value. The function __mlock_posix_error_return should
return a proper error for mlock, converting the return value from
__get_user_pages. It checks for EFAULT and ENOMEM. Actually
__get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.
So it seems to me that we could return to user space not expected value.
I can't see them on the man page. In addition we shouldn't ever return
ERESTARTSYS to the user space but EINTR. According to the man pages
maybe we should return EAGAIN in these cases. Am I missing something?
Thanks,
Marco
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Return value of __mm_populate
2013-04-13 12:14 Return value of __mm_populate Marco Stornelli
@ 2013-04-13 12:41 ` Marco
2013-04-14 0:18 ` KOSAKI Motohiro
1 sibling, 0 replies; 4+ messages in thread
From: Marco @ 2013-04-13 12:41 UTC (permalink / raw)
To: linux-mm; +Cc: Linux Kernel
Adding in cc: lkml
Il 13/04/2013 14:14, Marco Stornelli ha scritto:
> Hi,
>
> I was seeing the code of __mm_populate (in -next) and I've got a doubt
> about the return value. The function __mlock_posix_error_return should
> return a proper error for mlock, converting the return value from
> __get_user_pages. It checks for EFAULT and ENOMEM. Actually
> __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.
> So it seems to me that we could return to user space not expected value.
> I can't see them on the man page. In addition we shouldn't ever return
> ERESTARTSYS to the user space but EINTR. According to the man pages
> maybe we should return EAGAIN in these cases. Am I missing something?
>
> Thanks,
>
> Marco
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Return value of __mm_populate
2013-04-13 12:14 Return value of __mm_populate Marco Stornelli
2013-04-13 12:41 ` Marco
@ 2013-04-14 0:18 ` KOSAKI Motohiro
2013-04-14 7:25 ` Marco Stornelli
1 sibling, 1 reply; 4+ messages in thread
From: KOSAKI Motohiro @ 2013-04-14 0:18 UTC (permalink / raw)
To: Marco Stornelli; +Cc: linux-mm, Linux FS Devel, kosaki.motohiro, lkml
(4/13/13 5:14 AM), Marco Stornelli wrote:
> Hi,
>
> I was seeing the code of __mm_populate (in -next) and I've got a doubt
> about the return value. The function __mlock_posix_error_return should
> return a proper error for mlock, converting the return value from
> __get_user_pages. It checks for EFAULT and ENOMEM. Actually
> __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.
__get_user_pages doesn't return EHWPOISON if FOLL_HWPOISON is not specified.
I'm not expert ERESTARTSYS. I understand correctly, ERESTARTSYS is only returned
when signal received, and signal handling routine (e.g. do_signal) modify EIP and
hidden ERESTARTSYS from userland generically.
> So it seems to me that we could return to user space not expected value.
> I can't see them on the man page. In addition we shouldn't ever return
> ERESTARTSYS to the user space but EINTR. According to the man pages
> maybe we should return EAGAIN in these cases. Am I missing something?
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Return value of __mm_populate
2013-04-14 0:18 ` KOSAKI Motohiro
@ 2013-04-14 7:25 ` Marco Stornelli
0 siblings, 0 replies; 4+ messages in thread
From: Marco Stornelli @ 2013-04-14 7:25 UTC (permalink / raw)
To: KOSAKI Motohiro; +Cc: linux-mm, lkml
Hi,
Il 14/04/2013 02:18, KOSAKI Motohiro ha scritto:
> (4/13/13 5:14 AM), Marco Stornelli wrote:
>> Hi,
>>
>> I was seeing the code of __mm_populate (in -next) and I've got a doubt
>> about the return value. The function __mlock_posix_error_return should
>> return a proper error for mlock, converting the return value from
>> __get_user_pages. It checks for EFAULT and ENOMEM. Actually
>> __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.
>
> __get_user_pages doesn't return EHWPOISON if FOLL_HWPOISON is not specified.
> I'm not expert ERESTARTSYS. I understand correctly, ERESTARTSYS is only returned
> when signal received, and signal handling routine (e.g. do_signal) modify EIP and
> hidden ERESTARTSYS from userland generically.
>
Yep, you're right, the "magic" is inside the signal management. Thanks!!
Marco
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2013-04-13 12:14 Return value of __mm_populate Marco Stornelli
2013-04-13 12:41 ` Marco
2013-04-14 0:18 ` KOSAKI Motohiro
2013-04-14 7:25 ` Marco Stornelli
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