Messages in this thread | | | Date | Tue, 6 Apr 2010 15:38:47 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH -mm 2/4] oom: select_bad_process: PF_EXITING check should take ->mm into account |
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On 04/06, anfei wrote: > > On Tue, Apr 06, 2010 at 02:18:11PM +0200, Oleg Nesterov wrote: > > > > I do not really know what is the "right" solution. Even if we fix this > > check for mt case, we also have CLONE_VM tasks. > > > What about checking mm->mm_users too? If there are any other users, > just let badness judge. CLONE_VM tasks but not mt seem rare, and > badness doesn't consider it too.
Even if we forget about get_task_mm() which increments mm_users, it is not clear to me how to do this check correctly.
Say, mm_users > 1 but SIGNAL_GROUP_EXIT is set. This means this process is exiting and (ignoring CLONE_VM task) it is going to release its ->mm. But otoh mm can be NULL.
Perhaps we can do
if ((PF_EXITING && thread_group_empty(p) || (p->signal->flags & SIGNAL_GROUP_EXIT) { // OK, it is exiting
bool has_mm = false; do { if (t->mm) { has_mm = true; break; } } while_each_thread(p, t); if (!has_mm) continue;
if (p != current) return ERR_PTR(-1); ... }
I dunno.
Oleg.
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