Re: [RFC PATCH 0/4] mm/vmscan: honour node reclaim limits per type

[Ridong Chen <ridong.chen@linux.dev>]

On 8/21/2026 7:20 PM, Michal Hocko wrote:
> On Fri 21-08-26 19:10:45, Ridong Chen wrote:
>>>> Did you mean that min_slab_pages and min_unmapped_pages should influence
>>>> proactive per-node reclaim?
>>>

I apologize for being incoherent in my last email, it was after a full day of 
work. What I wanted to say is that min_slab_pages and min_unmapped_pages should 
*not* influence proactive per-node reclaim.

>>> Nope, exactly opposite
>>>
>>
>> I would really appreciate it if you could clarify this further. Sorry, I'm
>> not sure I fully understand what you meant.
> 
> pro-active (userspace triggered) node reclaim should completely ignore
> all those historical node_reclaim tunables.

Yeah, this matches my understanding. Apologies again for the confusing reply.

Since Johannes has acked patch 3, perhaps we can simply remove the conditional 
check in __node_reclaim and keep the shrink loop as follows:

```
@@ -7906,16 +7906,16 @@ static unsigned long __node_reclaim(struct pglist_data 
*pgdat,
  	noreclaim_flag = memalloc_noreclaim_save();
  	set_task_reclaim_state(p, &sc->reclaim_state);

-	if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages ||
-	    node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) > pgdat->min_slab_pages) {
-		/*
-		 * Free memory by calling shrink node with increasing
-		 * priorities until we have enough memory freed.
-		 */
-		do {
-			shrink_node(pgdat, sc);
-		} while (sc->nr_reclaimed < nr_pages && --sc->priority >= 0);
-	}
+	/*
+	 * Free memory by calling shrink node with increasing
+	 * priorities until we have enough memory freed.
+	 *
+	 * What to reclaim is gated per type by sc->skip_slab_reclaim and
+	 * sc->skip_file_reclaim.
+	 */
+	do {
+		shrink_node(pgdat, sc);
+	} while (sc->nr_reclaimed < nr_pages && --sc->priority >= 0);

  	set_task_reclaim_state(p, NULL);
  	memalloc_noreclaim_restore(noreclaim_flag);

```

-- 
Best regards
Ridong