linux-kernel - Re: [PATCH 4/4] mm: introduce per-node proactive reclaim interface

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Message-Id: <20250717154649.796cca17cf422783a79b4e5a@linux-foundation.org>
Date: Thu, 17 Jul 2025 15:46:49 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Davidlohr Bueso <dave@...olabs.net>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>, mhocko@...nel.org,
 hannes@...xchg.org, shakeel.butt@...ux.dev, yosryahmed@...gle.com,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] mm: introduce per-node proactive reclaim interface

On Thu, 17 Jul 2025 09:26:37 -0700 Davidlohr Bueso <dave@...olabs.net> wrote:

> >> +			if (test_and_set_bit_lock(PGDAT_RECLAIM_LOCKED,
> >> +						  &pgdat->flags))
> >> +				return -EAGAIN;
> >
> >Isn't EBUSY a better choice here?
> >At least to distinguish between no reclaimable memory left and
> >somebody else is abusing the same interface cases.
> 
> Yes, I agree.

From: Andrew Morton <akpm@...ux-foundation.org>
Subject: mm-introduce-per-node-proactive-reclaim-interface-fix
Date: Thu Jul 17 03:44:14 PM PDT 2025

user_proactive_reclaim(): return -EBUSY on PGDAT_RECLAIM_LOCKED
contention, per Roman

Cc: Davidlohr Bueso <dave@...olabs.net>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: Yosry Ahmed <yosryahmed@...gle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 mm/vmscan.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/vmscan.c~mm-introduce-per-node-proactive-reclaim-interface-fix
+++ a/mm/vmscan.c
@@ -7818,7 +7818,7 @@ int user_proactive_reclaim(char *buf,
 
 			if (test_and_set_bit_lock(PGDAT_RECLAIM_LOCKED,
 						  &pgdat->flags))
-				return -EAGAIN;
+				return -EBUSY;
 
 			reclaimed = __node_reclaim(pgdat, gfp_mask,
 						   batch_size, &sc);
_