Messages in this thread | | | Date | Sun, 10 May 2009 17:26:37 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [patch 06/11 -mmotm] oom: move oom_adj value from task_struct to mm_struct |
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On Mon, 11 May 2009, KOSAKI Motohiro wrote:
> > > The per-task oom_adj value is a characteristic of its mm more than the > > task itself since it's not possible to oom kill any thread that shares > > the mm. If a task were to be killed while attached to an mm that could > > not be freed because another thread were set to OOM_DISABLE, it would > > have needlessly been terminated since there is no potential for future > > memory freeing. > > > > This patch moves oomkilladj (now more appropriately named oom_adj) from > > struct task_struct to struct mm_struct. This requires task_lock() on a > > task to check its oom_adj value to protect against exec, but it's already > > necessary to take the lock when dereferencing the mm to find the total VM > > size for the badness heuristic. > > > > This fixes a livelock if the oom killer chooses a task and another thread > > sharing the same memory has an oom_adj value of OOM_DISABLE. This occurs > > because oom_kill_task() repeatedly returns 1 and refuses to kill the > > chosen task while select_bad_process() will repeatedly choose the same > > task during the next retry. > > > > Taking task_lock() in select_bad_process() to check for OOM_DISABLE and > > in oom_kill_task() to check for threads sharing the same memory will be > > removed in the next patch in this series where it will no longer be > > necessary. > > > > Writing to /proc/pid/oom_adj for a kthread will now return -EINVAL since > > these threads are immune from oom killing already. They simply report an > > oom_adj value of OOM_DISABLE. > > David, staging driver shold be standalone. > Please don't change core kernel for staging. > > if you merge it into mainline, I suggest to you help the driver graduate > staging. >
Umm, all my patches apply fine against mainline since the Android lowmemorykiller is already in Linus' tree. This patch moves oomkilladj from struct task_struct to struct mm_struct and since that's used for procfs, the oom killer, and the Android lowmemorykiller, I need to modify all of them so the kernel will compile with CONFIG_ANDROID_LOW_MEMORY_KILLER.
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