Messages in this thread | | | Date | Fri, 5 Dec 2014 15:46:38 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH v2 1/1] oom: don't assume that a coredumping thread will exit soon |
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On Wed, 3 Dec 2014, Oleg Nesterov wrote:
> oom_kill.c assumes that PF_EXITING task should exit and free the memory > soon. This is wrong in many ways and one important case is the coredump. > A task can sleep in exit_mm() "forever" while the coredumping sub-thread > can need more memory. > > Change the PF_EXITING checks to take SIGNAL_GROUP_COREDUMP into account, > we add the new trivial helper for that. > > Note: this is only the first step, this patch doesn't try to solve other > problems. The SIGNAL_GROUP_COREDUMP check is obviously racy, a task can > participate in coredump after it was already observed in PF_EXITING state, > so TIF_MEMDIE (which also blocks oom-killer) still can be wrongly set. > fatal_signal_pending() can be true because of SIGNAL_GROUP_COREDUMP so > out_of_memory() and mem_cgroup_out_of_memory() shouldn't blindly trust it. > And even the name/usage of the new helper is confusing, an exiting thread > can only free its ->mm if it is the only/last task in thread group. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
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