[PATCH] fork.2: EAGAIN is not reported when task allocation fails

[PATCH] fork.2: EAGAIN is not reported when task allocation fails

[Michal Hocko]

Hi,
I am not sure why we have:
"
EAGAIN fork() cannot allocate sufficient memory to copy the parent's
page tables and allocate a task structure for the child.
"
but it doesn't seem to reflect the reality. The text seems to be there
from the time when man-pages were moved to git so there is no history
for it. Unless I am missing something we need the patch below.

Thanks!
---
>From 9d56f4b46d604fc52aed6d87aac8fa5719ede058 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
Date: Tue, 3 Feb 2015 16:34:45 +0100
Subject: [PATCH] fork.2: EAGAIN is not reported when task allocation fails

The man page currently claims:
"
EAGAIN fork() cannot allocate sufficient memory to copy the parent's
page tables and allocate a task structure for the child.
"

but the kernel reports both dup_task_struct and dup_mm failures as
ENOMEM to the userspace. This seems to be the case from early 2.x times
so let's simply remove this part.

Signed-off-by: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
---
 man2/fork.2 | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/man2/fork.2 b/man2/fork.2
index e6695ade6f76..6aa91a93e545 100644
--- a/man2/fork.2
+++ b/man2/fork.2
@@ -185,11 +185,6 @@ is set appropriately.
 .SH ERRORS
 .TP
 .B EAGAIN
-.BR fork ()
-cannot allocate sufficient memory to copy the parent's page tables and
-allocate a task structure for the child.
-.TP
-.B EAGAIN
 \" NOTE! The following should match the description in pthread_create(3)
 A system-imposed limit on the number of threads was encountered.
 There are a number of limits that may trigger this error: the
-- 
2.1.4

-- 
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] fork.2: EAGAIN is not reported when task allocation fails

[Michael Kerrisk (man-pages)]

On 02/03/2015 04:48 PM, Michal Hocko wrote:
> Hi,
> I am not sure why we have:
> "
> EAGAIN fork() cannot allocate sufficient memory to copy the parent's
> page tables and allocate a task structure for the child.
> "
> but it doesn't seem to reflect the reality. The text seems to be there
> from the time when man-pages were moved to git so there is no history
> for it. Unless I am missing something we need the patch below.
> 
> Thanks!

Thanks, Michal. Applied.

Cheers,

Michael


> ---
>>From 9d56f4b46d604fc52aed6d87aac8fa5719ede058 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
> Date: Tue, 3 Feb 2015 16:34:45 +0100
> Subject: [PATCH] fork.2: EAGAIN is not reported when task allocation fails
> 
> The man page currently claims:
> "
> EAGAIN fork() cannot allocate sufficient memory to copy the parent's
> page tables and allocate a task structure for the child.
> "
> 
> but the kernel reports both dup_task_struct and dup_mm failures as
> ENOMEM to the userspace. This seems to be the case from early 2.x times
> so let's simply remove this part.
> 
> Signed-off-by: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
> ---
>  man2/fork.2 | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/man2/fork.2 b/man2/fork.2
> index e6695ade6f76..6aa91a93e545 100644
> --- a/man2/fork.2
> +++ b/man2/fork.2
> @@ -185,11 +185,6 @@ is set appropriately.
>  .SH ERRORS
>  .TP
>  .B EAGAIN
> -.BR fork ()
> -cannot allocate sufficient memory to copy the parent's page tables and
> -allocate a task structure for the child.
> -.TP
> -.B EAGAIN
>  \" NOTE! The following should match the description in pthread_create(3)
>  A system-imposed limit on the number of threads was encountered.
>  There are a number of limits that may trigger this error: the
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html