From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] radix-tree: account nodes to memcg only if explicitly requested
Date: Tue, 2 Aug 2016 15:42:20 +0300 [thread overview]
Message-ID: <20160802124220.GC13263@esperanza> (raw)
In-Reply-To: <20160802115111.GG12403@dhcp22.suse.cz>
On Tue, Aug 02, 2016 at 01:51:12PM +0200, Michal Hocko wrote:
> On Mon 01-08-16 16:13:08, Vladimir Davydov wrote:
> > Radix trees may be used not only for storing page cache pages, so
> > unconditionally accounting radix tree nodes to the current memory cgroup
> > is bad: if a radix tree node is used for storing data shared among
> > different cgroups we risk pinning dead memory cgroups forever. So let's
> > only account radix tree nodes if it was explicitly requested by passing
> > __GFP_ACCOUNT to INIT_RADIX_TREE. Currently, we only want to account
> > page cache entries, so mark mapping->page_tree so.
> >
> > Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
>
> OK, the patch makes sense to me. Such a false sharing would be really
> tedious to debug
>
> Do we want to mark it for stable 4.6 to prevent from some pathological
> issues. The patch is simple enough.
Makes sense, expecially taking into account that kmemcg is enabled by
default now. I'll resend the patch for stable then.
>
> Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!
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WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] radix-tree: account nodes to memcg only if explicitly requested
Date: Tue, 2 Aug 2016 15:42:20 +0300 [thread overview]
Message-ID: <20160802124220.GC13263@esperanza> (raw)
In-Reply-To: <20160802115111.GG12403@dhcp22.suse.cz>
On Tue, Aug 02, 2016 at 01:51:12PM +0200, Michal Hocko wrote:
> On Mon 01-08-16 16:13:08, Vladimir Davydov wrote:
> > Radix trees may be used not only for storing page cache pages, so
> > unconditionally accounting radix tree nodes to the current memory cgroup
> > is bad: if a radix tree node is used for storing data shared among
> > different cgroups we risk pinning dead memory cgroups forever. So let's
> > only account radix tree nodes if it was explicitly requested by passing
> > __GFP_ACCOUNT to INIT_RADIX_TREE. Currently, we only want to account
> > page cache entries, so mark mapping->page_tree so.
> >
> > Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
>
> OK, the patch makes sense to me. Such a false sharing would be really
> tedious to debug
>
> Do we want to mark it for stable 4.6 to prevent from some pathological
> issues. The patch is simple enough.
Makes sense, expecially taking into account that kmemcg is enabled by
default now. I'll resend the patch for stable then.
>
> Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!
next prev parent reply other threads:[~2016-08-02 12:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 13:13 [PATCH] radix-tree: account nodes to memcg only if explicitly requested Vladimir Davydov
2016-08-01 13:13 ` Vladimir Davydov
2016-08-01 15:24 ` Johannes Weiner
2016-08-01 15:24 ` Johannes Weiner
2016-08-01 16:06 ` Vladimir Davydov
2016-08-01 16:06 ` Vladimir Davydov
2016-08-01 17:14 ` Johannes Weiner
2016-08-01 17:14 ` Johannes Weiner
2016-08-02 11:51 ` Michal Hocko
2016-08-02 11:51 ` Michal Hocko
2016-08-02 12:42 ` Vladimir Davydov [this message]
2016-08-02 12:42 ` Vladimir Davydov
2016-08-02 12:46 ` Michal Hocko
2016-08-02 12:46 ` Michal Hocko
2016-08-02 18:51 ` Andrew Morton
2016-08-02 18:51 ` Andrew Morton
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