diff mbox series

[v3,01/14] mm/mempolicy: Add comment for missing LOCAL

Message ID 1614766858-90344-2-git-send-email-feng.tang@intel.com (mailing list archive)
State New
Headers show
Series Introduced multi-preference mempolicy | expand

Commit Message

Feng Tang March 3, 2021, 10:20 a.m. UTC
From: Ben Widawsky <ben.widawsky@intel.com>

MPOL_LOCAL is a bit weird because it is simply a different name for an
existing behavior (preferred policy with no node mask). It has been this
way since it was added here:
commit 479e2802d09f ("mm: mempolicy: Make MPOL_LOCAL a real policy")

It is so similar to MPOL_PREFERRED in fact that when the policy is
created in mpol_new, the mode is set as PREFERRED, and an internal state
representing LOCAL doesn't exist.

To prevent future explorers from scratching their head as to why
MPOL_LOCAL isn't defined in the mpol_ops table, add a small comment
explaining the situations.

v2:
Change comment to refer to mpol_new (Michal)

Link: https://lore.kernel.org/r/20200630212517.308045-2-ben.widawsky@intel.com
#Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
---
 mm/mempolicy.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Feng Tang March 10, 2021, 6:27 a.m. UTC | #1
On Wed, Mar 03, 2021 at 06:20:45PM +0800, Feng Tang wrote:
> From: Ben Widawsky <ben.widawsky@intel.com>
> 
> MPOL_LOCAL is a bit weird because it is simply a different name for an
> existing behavior (preferred policy with no node mask). It has been this
> way since it was added here:
> commit 479e2802d09f ("mm: mempolicy: Make MPOL_LOCAL a real policy")
> 
> It is so similar to MPOL_PREFERRED in fact that when the policy is
> created in mpol_new, the mode is set as PREFERRED, and an internal state
> representing LOCAL doesn't exist.
> 
> To prevent future explorers from scratching their head as to why
> MPOL_LOCAL isn't defined in the mpol_ops table, add a small comment
> explaining the situations.
> 
> v2:
> Change comment to refer to mpol_new (Michal)
> 
> Link: https://lore.kernel.org/r/20200630212517.308045-2-ben.widawsky@intel.com
> #Acked-by: Michal Hocko <mhocko@suse.com>

This shouldn't be masked:

Acked-by: Michal Hocko <mhocko@suse.com>

I did the mask when sending for internal review, and forgot to restore
it, sorry for the noise.

Thanks,
Feng

> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Feng Tang <feng.tang@intel.com>
> ---
>  mm/mempolicy.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 2c3a865..5730fc1 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -427,6 +427,7 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
>  		.create = mpol_new_bind,
>  		.rebind = mpol_rebind_nodemask,
>  	},
> +	/* [MPOL_LOCAL] - see mpol_new() */
>  };
>  
>  static int migrate_page_add(struct page *page, struct list_head *pagelist,
> -- 
> 2.7.4
diff mbox series

Patch

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 2c3a865..5730fc1 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -427,6 +427,7 @@  static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 		.create = mpol_new_bind,
 		.rebind = mpol_rebind_nodemask,
 	},
+	/* [MPOL_LOCAL] - see mpol_new() */
 };
 
 static int migrate_page_add(struct page *page, struct list_head *pagelist,