Ben Blum wrote:
> Quick vmalloc vs kmalloc fix to the case where array size is too large
>
> 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. Should be replaced
> entirely with a kernel-wide solution to this general problem.
>
> Depends on cgroup-pidlist-namespace.patch, cgroup-procs.patch
>
Since this is a patchset, you don't need to tell the dependencies of
this patch, at least not in changelog, but can put it ...
> Signed-off-by: Ben Blum <bblum@xxxxxxxxxx>
>
> ---
>
... here
--- <- followed by this mark
> kernel/cgroup.c | 34 ++++++++++++++++++++++++++++------
> 1 files changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 33d89be..0ed85fa 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -48,6 +48,7 @@
> #include <linux/namei.h>
> #include <linux/smp_lock.h>
> #include <linux/pid_namespace.h>
> +#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
>
Is this TODO different with the below one?
> #include <asm/atomic.h>
>
> @@ -2121,6 +2122,27 @@ 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
> + */
> +#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
I think order-0 is most robust and should be used as much as possible.
> +static inline void *pidlist_allocate(int count)
It's better to let gcc decide to inline it or not.
> +{
> + if (PIDLIST_TOO_LARGE(count))
> + return vmalloc(count * sizeof(pid_t));
> + else
> + return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
> +}
> +static inline void pidlist_free(void *p)
ditto
> +{
> + if (is_vmalloc_addr(p))
> + vfree(p);
> + else
> + kfree(p);
> +}
> +
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