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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>
This commit is contained in:
Ethan Solomita 2007-07-15 23:38:16 -07:00 committed by Linus Torvalds
parent b71636e298
commit 462e00cc71
1 changed files with 8 additions and 0 deletions
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8
mm/memory.c
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@ -1055,6 +1055,14 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
do {
struct page *page;
/*
* If tsk is ooming, cut off its access to large memory
* allocations. It has a pending SIGKILL, but it can't
* be processed until returning to user space.
*/
if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
return -ENOMEM;
if (write)
foll_flags |= FOLL_WRITE;