From ace2bee839e08df324cb320763258dfd72e6120e Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Sat, 9 Jul 2022 15:44:56 +0000 Subject: 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 Cc: Shakeel Butt Cc: NeilBrown Signed-off-by: Yafang Shao Reviewed-by: Shakeel Butt Link: https://lore.kernel.org/r/20220709154457.57379-2-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/devmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index c2867068e5bd..1400561efb15 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -845,7 +845,7 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net, struct bpf_dtab_netdev *dev; dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev), - GFP_ATOMIC | __GFP_NOWARN, + GFP_NOWAIT | __GFP_NOWARN, dtab->map.numa_node); if (!dev) return ERR_PTR(-ENOMEM); -- cgit From bd82ea52f0ee2890b698155a6d7bf9ea5bd8930d Mon Sep 17 00:00:00 2001 From: Lorenzo Bianconi Date: Sat, 23 Jul 2022 19:17:10 +0200 Subject: bpf, devmap: Compute proper xdp_frame len redirecting frames Even if it is currently forbidden to XDP_REDIRECT a multi-frag xdp_frame into a devmap, compute proper xdp_frame length in __xdp_enqueue and is_valid_dst routines running xdp_get_frame_len(). Signed-off-by: Lorenzo Bianconi Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/894d99c01139e921bdb6868158ff8e67f661c072.1658596075.git.lorenzo@kernel.org --- kernel/bpf/devmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/devmap.c') diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 1400561efb15..a0e02b009487 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -477,7 +477,7 @@ static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf, if (!dev->netdev_ops->ndo_xdp_xmit) return -EOPNOTSUPP; - err = xdp_ok_fwd_dev(dev, xdpf->len); + err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf)); if (unlikely(err)) return err; @@ -536,7 +536,7 @@ static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf) !obj->dev->netdev_ops->ndo_xdp_xmit) return false; - if (xdp_ok_fwd_dev(obj->dev, xdpf->len)) + if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf))) return false; return true; -- cgit