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	oom: stop allocating user memory if TIF_MEMDIE is set
get_user_pages() can try to allocate a nearly unlimited amount of memory on behalf of a user process, even if that process has been OOM killed. The OOM kill occurs upon return to user space via a SIGKILL, but get_user_pages() will try allocate all its memory before returning. Change get_user_pages() to check for TIF_MEMDIE, and if set then return immediately. Signed-off-by: Ethan Solomita <solo@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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					@ -1055,6 +1055,14 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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		do {
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							do {
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			struct page *page;
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								struct page *page;
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								/*
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								 * If tsk is ooming, cut off its access to large memory
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								 * allocations. It has a pending SIGKILL, but it can't
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								 * be processed until returning to user space.
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								 */
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								if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
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									return -ENOMEM;
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			if (write)
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								if (write)
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				foll_flags |= FOLL_WRITE;
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									foll_flags |= FOLL_WRITE;
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