Re: [PATCH] gfp: GFP_RECLAIM_MASK should include __GFP_NO_KSWAPD

Michal Hocko
2015-10-14T07:34:32Z

On Wed 14-10-15 13:36:51, Pan Xinhui wrote:
> From: Pan Xinhui <xinhuix.pan@intel.com>
>
> GFP_RECLAIM_MASK was introduced in commit 6cb062296f73 ("Categorize GFP
> flags"). In slub subsystem, this macro controls slub's allocation
> behavior. In particular, some flags which are not in GFP_RECLAIM_MASK
> will be cleared. So when slub pass this new gfp_flag into page
> allocator, we might lost some very important flags.
>
> There are some mistakes when we introduce __GFP_NO_KSWAPD. This flag is
> used to avoid any scheduler-related codes recursive. But it seems like
> patch author forgot to add it into GFP_RECLAIM_MASK. So lets add it now.

This is no longer needed because GFP_RECLAIM_MASK contains __GFP_RECLAIM
now - have a look at
http://lkml.kernel.org/r/1442832762-7247-7-git-send-email-mgorman%40techsingularity.net
which is sitting in the mmotm tree.

> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> ---
> include/linux/gfp.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index f92cbd2..9ebad4d 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -130,7 +130,8 @@ struct vm_area_struct;
> /* Control page allocator reclaim behavior */
> #define GFP_RECLAIM_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
> __GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
> - __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
> + __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\
> + __GFP_NO_KSWAPD)
>
> /* Control slab gfp mask during early boot */
> #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS))
> --
> 1.9.1

--
Michal Hocko
SUSE Labs