Re: [RFC PATCH] mm/oom: detect and kill task which has allocation forbidden by cpuset limit

[Feng Tang]

On Wed, Sep 01, 2021 at 10:44:02AM +0800, Tang, Feng wrote:
[SNIP]
> > So I'd agree in this case that it would be better to simply fail the 
> > allocation.
> 
> I agree with yours and Michal's comments, putting it in the OOM code
> is a little late and wastes cpu cycles.
> 
> > Feng, would you move this check to __alloc_pages_may_oom() like the other 
> > special cases and simply fail rather than call into the oom killer?
> 
> Will explore more in this direction, thanks!
 
I tried below patch, which can solve the blindly killing issue, that
the docker processes will see page allocation errors, and eventually 
quit running.

Thanks,
Feng

---
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index eeb3a9cb36bb..d1ae77be45a2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4271,10 +4271,18 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
 		.gfp_mask = gfp_mask,
 		.order = order,
 	};
-	struct page *page;
+	struct page *page = NULL;
+	struct zoneref *z;
 
 	*did_some_progress = 0;
 
+	if (cpusets_enabled() && (gfp_mask & __GFP_HARDWALL)) {
+		z = first_zones_zonelist(ac->zonelist,
+			gfp_zone(gfp_mask), &cpuset_current_mems_allowed);
+		if (!z->zone)
+			goto out;
+	}
+
 	/*
 	 * Acquire the oom lock.  If that fails, somebody else is
 	 * making progress for us.