Re: [PATCH 4/8] Use vmalloc for large cgroups pidlist allocations

[Li Zefan <lizf@cn.fujitsu.com>]

Paul Menage wrote:
> From: Ben Blum <bblum@google.com>
> 
> 
> Use vmalloc for large cgroups pidlist allocations
> 
> Separates all pidlist allocation requests to a separate function that judges
> based on the requested size whether or not the array needs to be vmalloced or
> can be gotten via kmalloc, and similar for kfree/vfree.
> 
> Signed-off-by: Ben Blum <bblum@google.com>
> Signed-off-by: Paul Menage <menage@google.com>
> 

Acked-by: Li Zefan <lizf@cn.fujitsu.com>

> ---
> 
>  kernel/cgroup.c |   47 ++++++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 42 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index d207871..7e2b285 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -50,6 +50,7 @@
>  #include <linux/smp_lock.h>
>  #include <linux/pid_namespace.h>
>  #include <linux/idr.h>
> +#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
>  
>  #include <asm/atomic.h>
>  
> @@ -2351,6 +2352,42 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
>   */
>  
>  /*
> + * The following two functions "fix" the issue where there are more pids
> + * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
> + * TODO: replace with a kernel-wide solution to this problem
> + */

I come to realize the "procs" file will make it much harder to convert
vmalloc/kmalloc with a different solution..