From: "Michael S. Tsirkin" <mst@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
Vladimir Davydov <vdavydov@parallels.com>
Subject: Re: [PATCH 09/10] vhost, mm: make sure that oom_reaper doesn't reap memory read by vhost
Date: Sat, 13 Aug 2016 03:15:00 +0300 [thread overview]
Message-ID: <20160813001500.yvmv67cram3bp7ug@redhat.com> (raw)
In-Reply-To: <20160812132140.GA776@redhat.com>
On Fri, Aug 12, 2016 at 03:21:41PM +0200, Oleg Nesterov wrote:
> Whats really interesting is that I still fail to understand do we really
> need this hack, iiuc you are not sure too, and Michael didn't bother to
> explain why a bogus zero from anon memory is worse than other problems
> caused by SIGKKILL from oom-kill.c.
vhost thread will die, but vcpu thread is going on. If it's memory is
corrupted because vhost read 0 and uses that as an array index, it can
do things like corrupt the disk, so it can't be restarted.
But I really wish we didn't need this special-casing. Can't PTEs be
made invalid on oom instead of pointing them at the zero page? And then
won't memory accesses trigger pagefaults instead of returning 0? That
would make regular copy_from_user machinery do the right thing,
making vhost stop running as appropriate.
--
MST
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next prev parent reply other threads:[~2016-08-13 0:15 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-28 19:42 [RFC PATCH 0/10] fortify oom killer even more Michal Hocko
2016-07-28 19:42 ` [PATCH 01/10] mm,oom_reaper: Reduce find_lock_task_mm() usage Michal Hocko
2016-07-28 19:42 ` [PATCH 02/10] mm,oom_reaper: Do not attempt to reap a task twice Michal Hocko
2016-07-28 19:42 ` [PATCH 03/10] oom: keep mm of the killed task available Michal Hocko
2016-07-28 19:42 ` [PATCH 04/10] mm, oom: get rid of signal_struct::oom_victims Michal Hocko
2016-07-28 19:42 ` [PATCH 05/10] kernel, oom: fix potential pgd_lock deadlock from __mmdrop Michal Hocko
2016-07-28 19:42 ` [PATCH 06/10] oom, suspend: fix oom_killer_disable vs. pm suspend properly Michal Hocko
2016-07-28 19:42 ` [PATCH 07/10] mm, oom: enforce exit_oom_victim on current task Michal Hocko
2016-07-28 19:42 ` [PATCH 08/10] exit, oom: postpone exit_oom_victim to later Michal Hocko
2016-07-30 8:20 ` Tetsuo Handa
2016-07-31 9:35 ` Michal Hocko
2016-07-31 10:19 ` Michal Hocko
2016-08-01 10:46 ` Tetsuo Handa
2016-08-01 11:33 ` Michal Hocko
2016-08-02 10:32 ` Tetsuo Handa
2016-08-02 11:31 ` Michal Hocko
2016-07-28 19:42 ` [PATCH 09/10] vhost, mm: make sure that oom_reaper doesn't reap memory read by vhost Michal Hocko
2016-07-28 20:41 ` Michael S. Tsirkin
2016-07-29 6:04 ` Michal Hocko
2016-07-29 13:14 ` Michael S. Tsirkin
2016-07-29 13:35 ` Michal Hocko
2016-07-29 17:57 ` Michael S. Tsirkin
2016-07-31 9:44 ` Michal Hocko
2016-08-12 9:42 ` Michal Hocko
2016-08-12 13:21 ` Oleg Nesterov
2016-08-12 14:41 ` Michal Hocko
2016-08-12 16:05 ` Oleg Nesterov
2016-08-12 15:57 ` Paul E. McKenney
2016-08-12 16:09 ` Oleg Nesterov
2016-08-12 16:26 ` Paul E. McKenney
2016-08-12 16:23 ` Michal Hocko
2016-08-13 0:15 ` Michael S. Tsirkin [this message]
2016-08-14 8:41 ` Michal Hocko
2016-08-14 16:57 ` Michael S. Tsirkin
2016-08-14 23:06 ` Michael S. Tsirkin
2016-08-15 9:49 ` Michal Hocko
2016-08-17 16:58 ` Michal Hocko
2016-08-22 13:03 ` Michal Hocko
2016-08-22 21:01 ` Michael S. Tsirkin
2016-08-23 7:55 ` Michal Hocko
2016-08-23 9:06 ` Michal Hocko
2016-08-23 12:54 ` Michael S. Tsirkin
2016-08-24 16:42 ` Michal Hocko
2016-08-12 9:43 ` Michal Hocko
2016-07-29 17:07 ` Oleg Nesterov
2016-07-31 9:11 ` Michal Hocko
2016-07-28 19:42 ` [PATCH 10/10] oom, oom_reaper: allow to reap mm shared by the kthreads Michal Hocko
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