From: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>
Cc: Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>,
Mel Gorman
<mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>,
David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Andrea Arcangeli
<aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Anshuman Khandual
<khandual-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
"Kirill A. Shutemov"
<kirill.shutemov-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [RFC 1/6] mm, page_alloc: fix more premature OOM due to race with cpuset update
Date: Wed, 17 May 2017 16:56:45 +0200 [thread overview]
Message-ID: <20170517145645.GO18247@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.20.1705170943090.8714-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
On Wed 17-05-17 09:48:25, Cristopher Lameter wrote:
> On Wed, 17 May 2017, Michal Hocko wrote:
>
> > > > So how are you going to distinguish VM_FAULT_OOM from an empty mempolicy
> > > > case in a raceless way?
> > >
> > > You dont have to do that if you do not create an empty mempolicy in the
> > > first place. The current kernel code avoids that by first allowing access
> > > to the new set of nodes and removing the old ones from the set when done.
> >
> > which is racy and as Vlastimil pointed out. If we simply fail such an
> > allocation the failure will go up the call chain until we hit the OOM
> > killer due to VM_FAULT_OOM. How would you want to handle that?
>
> The race is where? If you expand the node set during the move of the
> application then you are safe in terms of the legacy apps that did not
> include static bindings.
I am pretty sure it is describe in those changelogs and I won't repeat
it here.
> If you have screwy things like static mbinds in there then you are
> hopelessly lost anyways. You may have moved the process to another set
> of nodes but the static bindings may refer to a node no longer
> available. Thus the OOM is legitimate.
The point is that you do _not_ want such a process to trigger the OOM
because it can cause other processes being killed.
> At least a user space app could inspect
> the situation and come up with custom ways of dealing with the mess.
I do not really see how would this help to prevent a malicious user from
playing tricks.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-05-17 14:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170411140609.3787-1-vbabka@suse.cz>
[not found] ` <20170411140609.3787-2-vbabka@suse.cz>
[not found] ` <alpine.DEB.2.20.1704111152170.25069@east.gentwo.org>
[not found] ` <alpine.DEB.2.20.1704111152170.25069-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-04-11 19:00 ` [RFC 1/6] mm, page_alloc: fix more premature OOM due to race with cpuset update Vlastimil Babka
2017-04-12 21:25 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1704121617040.28335-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-04-13 6:24 ` Vlastimil Babka
2017-04-14 20:37 ` Christoph Lameter
2017-04-26 8:07 ` Vlastimil Babka
2017-04-30 21:33 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1704301628460.21533-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-05-17 9:20 ` Michal Hocko
[not found] ` <20170517092042.GH18247-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2017-05-17 13:56 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1705170855430.7925-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-05-17 14:05 ` Michal Hocko
2017-05-17 14:48 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1705170943090.8714-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-05-17 14:56 ` Michal Hocko [this message]
2017-05-17 15:25 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1705171021570.9487-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-05-18 9:08 ` Michal Hocko
[not found] ` <20170518090846.GD25462-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2017-05-18 16:57 ` Christoph Lameter
[not found] ` <alpine.DEB.2.20.1705181154450.27641-wcBtFHqTun5QOdAKl3ChDw@public.gmane.org>
2017-05-18 17:24 ` Michal Hocko
[not found] ` <20170518172424.GB30148-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2017-05-18 19:07 ` Christoph Lameter
2017-05-19 7:37 ` Michal Hocko
2017-05-17 15:27 ` Christoph Lameter
2017-05-18 10:03 ` Vlastimil Babka
2017-05-18 17:07 ` Christoph Lameter
2017-05-19 11:27 ` Vlastimil Babka
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