android, lowmemorykiller: remove task handoff notifier
The task handoff notifier leaks task_struct since it never gets freed after the callback returns NOTIFY_OK, which means it is responsible for doing so. It turns out the lowmemorykiller actually doesn't need this notifier at all. It's used to prevent unnecessary killing by waiting for a thread to exit as a result of lowmem_shrink(), however, it's possible to do this in the same way the kernel oom killer works by setting TIF_MEMDIE and avoid killing if we're still waiting for it to exit. The kernel oom killer will already automatically set TIF_MEMDIE for threads that are attempting to allocate memory that have a fatal signal. The thread selected by lowmem_shrink() will have such a signal after the lowmemorykiller sends it a SIGKILL, so this won't result in an unnecessary use of memory reserves for the thread to exit. This has the added benefit that we don't have to rely on CONFIG_PROFILING to prevent needlessly killing tasks. Reported-by: NWerner Landgraf <w.landgraf@ru.ru> Cc: stable@vger.kernel.org Signed-off-by: NDavid Rientjes <rientjes@google.com> Acked-by: NColin Cross <ccross@android.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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