Re: [PATCH 2/4] mm/memcg: make memory.reclaim interface generic

[Davidlohr Bueso]

On Thu, 17 Jul 2025, Andrew Morton wrote:

> On Thu, 17 Jul 2025 15:17:09 -0700 Shakeel Butt <shakeel.butt@xxxxxxxxx> wrote:
>
> > On Mon, Jun 23, 2025 at 11:58:49AM -0700, Davidlohr Bueso wrote:
> > > +
> > > +int user_proactive_reclaim(char *buf, struct mem_cgroup *memcg, pg_data_t *pgdat)
> > > +{
> > > +	unsigned int nr_retries = MAX_RECLAIM_RETRIES;
> > > +	unsigned long nr_to_reclaim, nr_reclaimed = 0;
> > > +	int swappiness = -1;
> > > +	char *old_buf, *start;
> > > +	substring_t args[MAX_OPT_ARGS];
> > > +
> > > +	if (!buf || (!memcg && !pgdat))
> >
> > I don't think this series is adding a use-case where both memcg and
> > pgdat are non-NULL, so let's error out on that as well.
>
> As a followup, please.  This has been in -next for four weeks and I'd
> prefer not to have to route around it (again).

From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Date: Thu, 17 Jul 2025 16:53:24 -0700
Subject: [PATCH] mm-introduce-per-node-proactive-reclaim-interface-fix

Both memcg and node is also a bogus case, per Shakeel.

Signed-off-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4598d18ba256..d5f7b1703234 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7758,7 +7758,7 @@ int user_proactive_reclaim(char *buf,
 	substring_t args[MAX_OPT_ARGS];
 	gfp_t gfp_mask = GFP_KERNEL;
 
-	if (!buf || (!memcg && !pgdat))
+	if (!buf || (!memcg && !pgdat) || (memcg && pgdat))
 		return -EINVAL;
 
 	buf = strstrip(buf);
--
2.39.5