linux-kernel - Re: Will the recent memory leak fixes be backported to longterm kernels?

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Message-ID: <20181102031600.GA15013@castle.DHCP.thefacebook.com>
Date:   Fri, 2 Nov 2018 03:16:08 +0000
From:   Roman Gushchin <guro@...com>
To:     Dexuan Cui <decui@...rosoft.com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>,
        "Shakeel Butt" <shakeelb@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        "Johannes Weiner" <hannes@...xchg.org>, Tejun Heo <tj@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Stable@...r.kernel.org" <Stable@...r.kernel.org>
Subject: Re: Will the recent memory leak fixes be backported to longterm
 kernels?

On Fri, Nov 02, 2018 at 02:45:42AM +0000, Dexuan Cui wrote:
> > From: Roman Gushchin <guro@...com>
> > Sent: Thursday, November 1, 2018 17:58
> > 
> > On Fri, Nov 02, 2018 at 12:16:02AM +0000, Dexuan Cui wrote:
> > Hello, Dexuan!
> > 
> > A couple of issues has been revealed recently, here are fixes
> > (hashes are from the next tree):
> > 
> > 5f4b04528b5f mm: don't reclaim inodes with many attached pages
> > 5a03b371ad6a mm: handle no memcg case in memcg_kmem_charge()
> > properly
> > 
> > These two patches should be added to the serie.
> 
> Thanks for the new info!
>  
> > Re stable backporting, I'd really wait for some time. Memory reclaim is a
> > quite complex and fragile area, so even if patches are correct by themselves,
> > they can easily cause a regression by revealing some other issues (as it was
> > with the inode reclaim case).
> 
> I totally agree. I'm now just wondering if there is any temporary workaround,
> even if that means we have to run the kernel with some features disabled or
> with a suboptimal performance?

I don't think there is any, except not using memory cgroups at all.
Limiting the amount of cgroups which are created and destroyed helps too:
a faulty service running under systemd can be especially painful.

Thanks!