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Date: Fri, 12 Jan 2024 09:10:33 -0800
From: Roman Gushchin <roman.gushchin@linux.dev>
To: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Shakeel Butt <shakeelb@google.com>,
	Muchun Song <muchun.song@linux.dev>, Tejun Heo <tj@kernel.org>,
	Dan Schatzberg <schatzberg.dan@gmail.com>, cgroups@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: memcontrol: don't throttle dying tasks on memory.high
Message-ID: <ZaFyiTFC-ped0IdA@P9FQF9L96D.corp.robot.car>
References: <20240111132902.389862-1-hannes@cmpxchg.org>
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 <20240111192807.GA424308@cmpxchg.org>
 <ZaFxn7JC8FeR-Si0@tiehlicka>
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In-Reply-To: <ZaFxn7JC8FeR-Si0@tiehlicka>

On Fri, Jan 12, 2024 at 06:06:39PM +0100, Michal Hocko wrote:
> On Thu 11-01-24 14:28:07, Johannes Weiner wrote:
> [...]
> > @@ -2867,11 +2882,17 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
> >  		}
> >  	} while ((memcg = parent_mem_cgroup(memcg)));
> >  
> > +	/*
> > +	 * Reclaim is set up above to be called from the userland
> > +	 * return path. But also attempt synchronous reclaim to avoid
> > +	 * excessive overrun while the task is still inside the
> > +	 * kernel. If this is successful, the return path will see it
> > +	 * when it rechecks the overage and simply bail out.
> > +	 */
> >  	if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH &&
> >  	    !(current->flags & PF_MEMALLOC) &&
> > -	    gfpflags_allow_blocking(gfp_mask)) {
> > +	    gfpflags_allow_blocking(gfp_mask))
> >  		mem_cgroup_handle_over_high(gfp_mask);
> 
> Have you lost the check for the dying task here?

It was moved into mem_cgroup_handle_over_high()'s body.