From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: memcg: unify force charging conditions
Currently the kernel force charges the allocations which have __GFP_HIGH
flag without triggering the memory reclaim. __GFP_HIGH indicates that the
caller is high priority and since commit 869712fd3de5 ("mm: memcontrol:
fix network errors from failing __GFP_ATOMIC charges") the kernel lets
such allocations do force charging. Please note that __GFP_ATOMIC has
been replaced by __GFP_HIGH.
__GFP_HIGH does not tell if the caller can block or can trigger reclaim.
There are separate checks to determine that. So, there is no need to skip
reclaiming for __GFP_HIGH allocations. So, handle __GFP_HIGH together
with __GFP_NOFAIL which also does force charging.
Please note that this is a noop change as there are no __GFP_HIGH
allocators in the kernel which also have __GFP_ACCOUNT (or SLAB_ACCOUNT)
and does not allow reclaim for now.
Link: https://lkml.kernel.org/r/20220211064917.2028469-3-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Chris Down <chris@xxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
--- a/mm/memcontrol.c~memcg-unify-force-charging-conditions
+++ a/mm/memcontrol.c
@@ -2566,15 +2566,6 @@ retry:
}
/*
- * Memcg doesn't have a dedicated reserve for atomic
- * allocations. But like the global atomic pool, we need to
- * put the burden of reclaim on regular allocation requests
- * and let these go through as privileged allocations.
- */
- if (gfp_mask & __GFP_ATOMIC)
- goto force;
-
- /*
* Prevent unbounded recursion when reclaim operations need to
* allocate memory. This might exceed the limits temporarily,
* but we prefer facilitating memory reclaim and getting back
@@ -2647,7 +2638,13 @@ retry:
goto retry;
}
nomem:
- if (!(gfp_mask & __GFP_NOFAIL))
+ /*
+ * Memcg doesn't have a dedicated reserve for atomic
+ * allocations. But like the global atomic pool, we need to
+ * put the burden of reclaim on regular allocation requests
+ * and let these go through as privileged allocations.
+ */
+ if (!(gfp_mask & (__GFP_NOFAIL | __GFP_HIGH)))
return -ENOMEM;
force:
/*
_
