[PATCH 4/8] mm,page_alloc: Make oom_reserves_allowed() even.

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

Since CONFIG_MMU=n kernels no longer waits for OOM victims forever,
there is no possibiligty of OOM lockup. Therefore, we can get rid of
special handling of oom_reserves_allowed().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
---
 mm/page_alloc.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6205d34..b915533 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3862,21 +3862,6 @@ static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
 	return alloc_flags;
 }
 
-static bool oom_reserves_allowed(struct task_struct *tsk)
-{
-	if (!tsk_is_oom_victim(tsk))
-		return false;
-
-	/*
-	 * !MMU doesn't have oom reaper so give access to memory reserves
-	 * only to the thread with TIF_MEMDIE set
-	 */
-	if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
-		return false;
-
-	return true;
-}
-
 /*
  * Distinguish requests which really need access to full memory
  * reserves from oom victims which can live with a portion of it
@@ -3892,7 +3877,7 @@ static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
 	if (!in_interrupt()) {
 		if (current->flags & PF_MEMALLOC)
 			return ALLOC_NO_WATERMARKS;
-		else if (oom_reserves_allowed(current))
+		else if (tsk_is_oom_victim(current))
 			return ALLOC_OOM;
 	}
 
-- 
1.8.3.1