android: binder: drop lru lock in isolate callback

Drop the global lru lock in isolate callback before calling
zap_page_range which calls cond_resched, and re-acquire the global lru
lock before returning.  Also change return code to LRU_REMOVED_RETRY.

Use mmput_async when fail to acquire mmap sem in an atomic context.

Fix "BUG: sleeping function called from invalid context"
errors when CONFIG_DEBUG_ATOMIC_SLEEP is enabled.

Also restore mmput_async, which was initially introduced in commit
ec8d7c14ea14 ("mm, oom_reaper: do not mmput synchronously from the oom
reaper context"), and was removed in commit 212925802454 ("mm: oom: let
oom_reap_task and exit_mmap run concurrently").

Link: http://lkml.kernel.org/r/[email protected]
Fixes: f2517eb76f1f2 ("android: binder: Add global lru shrinker to binder")
Signed-off-by: Sherry Yang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Reported-by: Kyle Yan <[email protected]>
Acked-by: Arve Hjønnevåg <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Martijn Coenen <[email protected]>
Cc: Todd Kjos <[email protected]>
Cc: Riley Andrews <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Hoeun Ryu <[email protected]>
Cc: Christopher Lameter <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 3a19c253bdb1..ae53e413fb13 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -84,6 +84,12 @@ static inline bool mmget_not_zero(struct mm_struct *mm)
 
 /* mmput gets rid of the mappings and all user-space */
 extern void mmput(struct mm_struct *);
+#ifdef CONFIG_MMU
+/* same as above but performs the slow path from the async context. Can
+ * be called from the atomic context as well
+ */
+void mmput_async(struct mm_struct *);
+#endif
 
 /* Grab a reference to a task's mm, if it is not already going away */
 extern struct mm_struct *get_task_mm(struct task_struct *task);