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| author | Yafang Shao <laoar.shao@gmail.com> | 2022-07-09 18:44:56 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-07-13 03:44:27 +0300 |
| commit | ace2bee839e08df324cb320763258dfd72e6120e (patch) | |
| tree | b41ecf0d5d4df51d4aeeaa90a1dad676ffca2a16 /kernel/bpf/local_storage.c | |
| parent | 1d5f82d9dd477d5c66e0214a68c3e4f308eadd6d (diff) | |
| download | linux-ace2bee839e08df324cb320763258dfd72e6120e.tar.xz | |
bpf: Make non-preallocated allocation low priority
GFP_ATOMIC doesn't cooperate well with memcg pressure so far, especially
if we allocate too much GFP_ATOMIC memory. For example, when we set the
memcg limit to limit a non-preallocated bpf memory, the GFP_ATOMIC can
easily break the memcg limit by force charge. So it is very dangerous to
use GFP_ATOMIC in non-preallocated case. One way to make it safe is to
remove __GFP_HIGH from GFP_ATOMIC, IOW, use (__GFP_ATOMIC |
__GFP_KSWAPD_RECLAIM) instead, then it will be limited if we allocate
too much memory. There's a plan to completely remove __GFP_ATOMIC in the
mm side[1], so let's use GFP_NOWAIT instead.
We introduced BPF_F_NO_PREALLOC is because full map pre-allocation is
too memory expensive for some cases. That means removing __GFP_HIGH
doesn't break the rule of BPF_F_NO_PREALLOC, but has the same goal with
it-avoiding issues caused by too much memory. So let's remove it.
This fix can also apply to other run-time allocations, for example, the
allocation in lpm trie, local storage and devmap. So let fix it
consistently over the bpf code
It also fixes a typo in the comment.
[1]. https://lore.kernel.org/linux-mm/163712397076.13692.4727608274002939094@noble.neil.brown.name/
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Link: https://lore.kernel.org/r/20220709154457.57379-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/local_storage.c')
| -rw-r--r-- | kernel/bpf/local_storage.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c index 8654fc97f5fe..49ef0ce040c7 100644 --- a/kernel/bpf/local_storage.c +++ b/kernel/bpf/local_storage.c @@ -165,7 +165,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *key, } new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size), - __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN, + __GFP_ZERO | GFP_NOWAIT | __GFP_NOWARN, map->numa_node); if (!new) return -ENOMEM; |