[PATCH v2] mm/oom_kill: remove unreachable __GFP_THISNODE check in constrained_alloc()

From: Ye Liu <[email protected]>

The __GFP_THISNODE check in constrained_alloc() is dead code: global
OOM is never triggered with __GFP_THISNODE (blocked in
__alloc_pages_may_oom before out_of_memory() is called), and memcg OOM
returns CONSTRAINT_MEMCG at the top of the function before reaching
this point. Remove the check, its stale comment, and update the
following comment that referenced __GFP_THISNODE.

Signed-off-by: Ye Liu <[email protected]>
---
v2:
 - Remove the dead code directly.
 - Link: https://lore.kernel.org/all/[email protected]/

 mm/oom_kill.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 5f372f6e26fa..fd3c476846a3 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -267,18 +267,11 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc)
 
 	if (!oc->zonelist)
 		return CONSTRAINT_NONE;
-	/*
-	 * Reach here only when __GFP_NOFAIL is used. So, we should avoid
-	 * to kill current.We have to random task kill in this case.
-	 * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
-	 */
-	if (oc->gfp_mask & __GFP_THISNODE)
-		return CONSTRAINT_NONE;
 
 	/*
-	 * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
-	 * the page allocator means a mempolicy is in effect.  Cpuset policy
-	 * is enforced in get_page_from_freelist().
+	 * A truncated nodemask in the page allocator means a mempolicy
+	 * is in effect.  Cpuset policy is enforced in
+	 * get_page_from_freelist().
 	 */
 	if (oc->nodemask &&
 	    !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
-- 
2.25.1