From 4aaa1685f750b293316d2a09cde2ea25be2a5de2 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 30 Jun 2022 15:17:54 -0700 Subject: [PATCH 1/4] mptcp: never fetch fwd memory from the subflow The memory accounting is broken in such exceptional code path, and after commit 4890b686f408 ("net: keep sk->sk_forward_alloc as small as possible") we can't find much help there. Drop the broken code. Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 883bea93c2aee..9a6a4ab337dcf 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -328,15 +328,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size) amt = sk_mem_pages(size); amount = amt << PAGE_SHIFT; - msk->rmem_fwd_alloc += amount; - if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) { - if (ssk->sk_forward_alloc < amount) { - msk->rmem_fwd_alloc -= amount; - return false; - } + if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) + return false; - ssk->sk_forward_alloc -= amount; - } + msk->rmem_fwd_alloc += amount; return true; } From d24141fe7b48d3572afb673ae350cf0e88caba6c Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 30 Jun 2022 15:17:55 -0700 Subject: [PATCH 2/4] mptcp: drop SK_RECLAIM_* macros After commit 4890b686f408 ("net: keep sk->sk_forward_alloc as small as possible"), the MPTCP protocol is the last SK_RECLAIM_CHUNK and SK_RECLAIM_THRESHOLD users. Update the MPTCP reclaim schema to match the core/TCP one and drop the mentioned macros. This additionally clean the MPTCP code a bit. Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 35 ++--------------------------------- 1 file changed, 2 insertions(+), 33 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 9a6a4ab337dcf..b4b4ca897e149 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -181,8 +181,8 @@ static void mptcp_rmem_uncharge(struct sock *sk, int size) reclaimable = msk->rmem_fwd_alloc - sk_unused_reserved_mem(sk); /* see sk_mem_uncharge() for the rationale behind the following schema */ - if (unlikely(reclaimable >= SK_RECLAIM_THRESHOLD)) - __mptcp_rmem_reclaim(sk, SK_RECLAIM_CHUNK); + if (unlikely(reclaimable >= PAGE_SIZE)) + __mptcp_rmem_reclaim(sk, reclaimable); } static void mptcp_rfree(struct sk_buff *skb) @@ -961,25 +961,6 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk, df->data_seq + df->data_len == msk->write_seq; } -static void __mptcp_mem_reclaim_partial(struct sock *sk) -{ - int reclaimable = mptcp_sk(sk)->rmem_fwd_alloc - sk_unused_reserved_mem(sk); - - lockdep_assert_held_once(&sk->sk_lock.slock); - - if (reclaimable > (int)PAGE_SIZE) - __mptcp_rmem_reclaim(sk, reclaimable - 1); - - sk_mem_reclaim(sk); -} - -static void mptcp_mem_reclaim_partial(struct sock *sk) -{ - mptcp_data_lock(sk); - __mptcp_mem_reclaim_partial(sk); - mptcp_data_unlock(sk); -} - static void dfrag_uncharge(struct sock *sk, int len) { sk_mem_uncharge(sk, len); @@ -999,7 +980,6 @@ static void __mptcp_clean_una(struct sock *sk) { struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_data_frag *dtmp, *dfrag; - bool cleaned = false; u64 snd_una; /* on fallback we just need to ignore snd_una, as this is really @@ -1022,7 +1002,6 @@ static void __mptcp_clean_una(struct sock *sk) } dfrag_clear(sk, dfrag); - cleaned = true; } dfrag = mptcp_rtx_head(sk); @@ -1044,7 +1023,6 @@ static void __mptcp_clean_una(struct sock *sk) dfrag->already_sent -= delta; dfrag_uncharge(sk, delta); - cleaned = true; } /* all retransmitted data acked, recovery completed */ @@ -1052,9 +1030,6 @@ static void __mptcp_clean_una(struct sock *sk) msk->recovery = false; out: - if (cleaned && tcp_under_memory_pressure(sk)) - __mptcp_mem_reclaim_partial(sk); - if (snd_una == READ_ONCE(msk->snd_nxt) && snd_una == READ_ONCE(msk->write_seq)) { if (mptcp_timer_pending(sk) && !mptcp_data_fin_enabled(msk)) @@ -1206,12 +1181,6 @@ static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, boo { gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation; - if (unlikely(tcp_under_memory_pressure(sk))) { - if (data_lock_held) - __mptcp_mem_reclaim_partial(sk); - else - mptcp_mem_reclaim_partial(sk); - } return __mptcp_alloc_tx_skb(sk, ssk, gfp); } From 69d93daec026cdda98e29e8edb12534bfa5b1a9b Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 30 Jun 2022 15:17:56 -0700 Subject: [PATCH 3/4] mptcp: refine memory scheduling Similar to commit 7c80b038d23e ("net: fix sk_wmem_schedule() and sk_rmem_schedule() errors"), let the MPTCP receive path schedule exactly the required amount of memory. Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index b4b4ca897e149..d77ca57f5e6ed 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -323,9 +323,10 @@ static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size) struct mptcp_sock *msk = mptcp_sk(sk); int amt, amount; - if (size < msk->rmem_fwd_alloc) + if (size <= msk->rmem_fwd_alloc) return true; + size -= msk->rmem_fwd_alloc; amt = sk_mem_pages(size); amount = amt << PAGE_SHIFT; if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV)) From e918c137db4083e59866d2aaa603887cbd9969bf Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 30 Jun 2022 15:17:57 -0700 Subject: [PATCH 4/4] net: remove SK_RECLAIM_THRESHOLD and SK_RECLAIM_CHUNK There are no more users for the mentioned macros, just drop them. Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- include/net/sock.h | 5 ----- 1 file changed, 5 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 40bbd0e8925b8..0dd43c3df49b9 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1619,11 +1619,6 @@ static inline void sk_mem_charge(struct sock *sk, int size) sk->sk_forward_alloc -= size; } -/* the following macros control memory reclaiming in mptcp_rmem_uncharge() - */ -#define SK_RECLAIM_THRESHOLD (1 << 21) -#define SK_RECLAIM_CHUNK (1 << 20) - static inline void sk_mem_uncharge(struct sock *sk, int size) { if (!sk_has_account(sk))