The patch titled
Subject: netvm: set PF_MEMALLOC as appropriate during SKB processing
has been added to the -mm tree. Its filename is
netvm-set-pf_memalloc-as-appropriate-during-skb-processing.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxx>
Subject: netvm: set PF_MEMALLOC as appropriate during SKB processing
In order to make sure pfmemalloc packets receive all memory needed to
proceed, ensure processing of pfmemalloc SKBs happens under PF_MEMALLOC.
This is limited to a subset of protocols that are expected to be used for
writing to swap. Taps are not allowed to use PF_MEMALLOC as these are
expected to communicate with userspace processes which could be paged out.
[a.p.zijlstra@xxxxxxxxx: Ideas taken from various patches]
[jslaby@xxxxxxx: Lock imbalance fix]
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Mike Christie <michaelc@xxxxxxxxxxx>
Cc: Eric B Munson <emunson@xxxxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/net/sock.h | 5 ++++
net/core/dev.c | 53 ++++++++++++++++++++++++++++++++++++++-----
net/core/sock.c | 16 ++++++++++++
3 files changed, 68 insertions(+), 6 deletions(-)
diff -puN include/net/sock.h~netvm-set-pf_memalloc-as-appropriate-during-skb-processing include/net/sock.h
--- a/include/net/sock.h~netvm-set-pf_memalloc-as-appropriate-during-skb-processing
+++ a/include/net/sock.h
@@ -754,8 +754,13 @@ static inline __must_check int sk_add_ba
return 0;
}
+extern int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+
static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
+ if (sk_memalloc_socks() && skb_pfmemalloc(skb))
+ return __sk_backlog_rcv(sk, skb);
+
return sk->sk_backlog_rcv(sk, skb);
}
diff -puN net/core/dev.c~netvm-set-pf_memalloc-as-appropriate-during-skb-processing net/core/dev.c
--- a/net/core/dev.c~netvm-set-pf_memalloc-as-appropriate-during-skb-processing
+++ a/net/core/dev.c
@@ -3156,6 +3156,23 @@ void netdev_rx_handler_unregister(struct
}
EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);
+/*
+ * Limit the use of PFMEMALLOC reserves to those protocols that implement
+ * the special handling of PFMEMALLOC skbs.
+ */
+static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
+{
+ switch (skb->protocol) {
+ case __constant_htons(ETH_P_ARP):
+ case __constant_htons(ETH_P_IP):
+ case __constant_htons(ETH_P_IPV6):
+ case __constant_htons(ETH_P_8021Q):
+ return true;
+ default:
+ return false;
+ }
+}
+
static int __netif_receive_skb(struct sk_buff *skb)
{
struct packet_type *ptype, *pt_prev;
@@ -3165,14 +3182,27 @@ static int __netif_receive_skb(struct sk
bool deliver_exact = false;
int ret = NET_RX_DROP;
__be16 type;
+ unsigned long pflags = current->flags;
net_timestamp_check(!netdev_tstamp_prequeue, skb);
trace_netif_receive_skb(skb);
+ /*
+ * PFMEMALLOC skbs are special, they should
+ * - be delivered to SOCK_MEMALLOC sockets only
+ * - stay away from userspace
+ * - have bounded memory usage
+ *
+ * Use PF_MEMALLOC as this saves us from propagating the allocation
+ * context down to all allocation sites.
+ */
+ if (sk_memalloc_socks() && skb_pfmemalloc(skb))
+ current->flags |= PF_MEMALLOC;
+
/* if we've gotten here through NAPI, check netpoll */
if (netpoll_receive_skb(skb))
- return NET_RX_DROP;
+ goto out;
if (!skb->skb_iif)
skb->skb_iif = skb->dev->ifindex;
@@ -3193,7 +3223,7 @@ another_round:
if (skb->protocol == cpu_to_be16(ETH_P_8021Q)) {
skb = vlan_untag(skb);
if (unlikely(!skb))
- goto out;
+ goto unlock;
}
#ifdef CONFIG_NET_CLS_ACT
@@ -3203,6 +3233,9 @@ another_round:
}
#endif
+ if (sk_memalloc_socks() && skb_pfmemalloc(skb))
+ goto skip_taps;
+
list_for_each_entry_rcu(ptype, &ptype_all, list) {
if (!ptype->dev || ptype->dev == skb->dev) {
if (pt_prev)
@@ -3211,13 +3244,18 @@ another_round:
}
}
+skip_taps:
#ifdef CONFIG_NET_CLS_ACT
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
- goto out;
+ goto unlock;
ncls:
#endif
+ if (sk_memalloc_socks() && skb_pfmemalloc(skb)
+ && !skb_pfmemalloc_protocol(skb))
+ goto drop;
+
rx_handler = rcu_dereference(skb->dev->rx_handler);
if (vlan_tx_tag_present(skb)) {
if (pt_prev) {
@@ -3227,7 +3265,7 @@ ncls:
if (vlan_do_receive(&skb, !rx_handler))
goto another_round;
else if (unlikely(!skb))
- goto out;
+ goto unlock;
}
if (rx_handler) {
@@ -3237,7 +3275,7 @@ ncls:
}
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
- goto out;
+ goto unlock;
case RX_HANDLER_ANOTHER:
goto another_round;
case RX_HANDLER_EXACT:
@@ -3267,6 +3305,7 @@ ncls:
if (pt_prev) {
ret = pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
} else {
+drop:
atomic_long_inc(&skb->dev->rx_dropped);
kfree_skb(skb);
/* Jamal, now you will not able to escape explaining
@@ -3275,8 +3314,10 @@ ncls:
ret = NET_RX_DROP;
}
-out:
+unlock:
rcu_read_unlock();
+out:
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
return ret;
}
diff -puN net/core/sock.c~netvm-set-pf_memalloc-as-appropriate-during-skb-processing net/core/sock.c
--- a/net/core/sock.c~netvm-set-pf_memalloc-as-appropriate-during-skb-processing
+++ a/net/core/sock.c
@@ -298,6 +298,22 @@ void sk_clear_memalloc(struct sock *sk)
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
+int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ int ret;
+ unsigned long pflags = current->flags;
+
+ /* these should have been dropped before queueing */
+ BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));
+
+ current->flags |= PF_MEMALLOC;
+ ret = sk->sk_backlog_rcv(sk, skb);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
+
+ return ret;
+}
+EXPORT_SYMBOL(__sk_backlog_rcv);
+
#if defined(CONFIG_CGROUPS)
#if !defined(CONFIG_NET_CLS_CGROUP)
int net_cls_subsys_id = -1;
_
Subject: Subject: netvm: set PF_MEMALLOC as appropriate during SKB processing
Patches currently in -mm which might be from mgorman@xxxxxxx are
origin.patch
linux-next.patch
memcg-prevent-oom-with-too-many-dirty-pages.patch
memcg-prevent-oom-with-too-many-dirty-pages-fix.patch
mm-do-not-use-page_count-without-a-page-pin.patch
mm-clean-up-__count_immobile_pages.patch
mm-hotplug-correctly-setup-fallback-zonelists-when-creating-new-pgdat.patch
mm-hotplug-correctly-add-new-zone-to-all-other-nodes-zone-lists.patch
mm-hotplug-free-zone-pageset-when-a-zone-becomes-empty.patch
mm-hotplug-mark-memory-hotplug-code-in-page_allocc-as-__meminit.patch
mm-factor-out-memory-isolate-functions.patch
mm-bug-fix-free-page-check-in-zone_watermark_ok.patch
memory-hotplug-fix-kswapd-looping-forever-problem.patch
memory-hotplug-fix-kswapd-looping-forever-problem-fix.patch
mm-slb-add-knowledge-of-pfmemalloc-reserve-pages.patch
mm-slub-optimise-the-slub-fast-path-to-avoid-pfmemalloc-checks.patch
mm-introduce-__gfp_memalloc-to-allow-access-to-emergency-reserves.patch
mm-allow-pf_memalloc-from-softirq-context.patch
mm-only-set-page-pfmemalloc-when-alloc_no_watermarks-was-used.patch
mm-ignore-mempolicies-when-using-alloc_no_watermark.patch
net-introduce-sk_gfp_atomic-to-allow-addition-of-gfp-flags-depending-on-the-individual-socket.patch
netvm-allow-the-use-of-__gfp_memalloc-by-specific-sockets.patch
netvm-allow-skb-allocation-to-use-pfmemalloc-reserves.patch
netvm-propagate-page-pfmemalloc-to-skb.patch
netvm-propagate-page-pfmemalloc-from-skb_alloc_page-to-skb.patch
netvm-set-pf_memalloc-as-appropriate-during-skb-processing.patch
mm-micro-optimise-slab-to-avoid-a-function-call.patch
nbd-set-sock_memalloc-for-access-to-pfmemalloc-reserves.patch
mm-throttle-direct-reclaimers-if-pf_memalloc-reserves-are-low-and-swap-is-backed-by-network-storage.patch
mm-account-for-the-number-of-times-direct-reclaimers-get-throttled.patch
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