Re: [RFC] /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_overcommit_hugepages

[Michal Hocko <mhocko@suse.cz>]

On Wed 05-01-11 10:36:47, CAI Qian wrote:
> From f90b54f9f5607128e375bd78d21e751c433b3cf6 Mon Sep 17 00:00:00 2001
> From: CAI Qian <caiqian@redhat.com>
> Date: Wed, 5 Jan 2011 23:26:57 +0800
> Subject: [PATCH] hugetlbfs: check invalid nr_hugepages and nr_overcommit_hugepages
> 
> First, nr_*hugepages* in procfs and sysfs do not check for invalid
> input like "". Second, when using oversize pages, nr_*hugepages* are
> expected to be allocated during boot time. Therefore, return -EINVAL
> for those cases.

I think that the two things should be split into two patches - one for
the proper input data handling and the other one for the size check.
Albeit, I am not sure about the size check because this is a thing that
is just a current implementation limitation and can be change later.

> 
> Signed-off-by: CAI Qian <caiqian@redhat.com>
> ---
>  fs/sysfs/file.c |    2 ++
>  mm/hugetlb.c    |   18 ++++++++++++++++--
>  2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index da3fefe..9f4ea67 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -207,6 +207,8 @@ flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t
>  		return -ENODEV;
>  
>  	rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
> +	if (!rc)
> +		return -EINVAL;

This doesn't look correct, you would imbalance sysfs_{get,put}_active.

[...]
-- 
Michal Hocko
L3 team 
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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