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Commit 84882cf

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kuba-mookuba-moo
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Revert "net: avoid double accounting for pure zerocopy skbs"
This reverts commit f1a456f. WARNING: CPU: 1 PID: 6819 at net/core/skbuff.c:5429 skb_try_coalesce+0x78b/0x7e0 CPU: 1 PID: 6819 Comm: xxxxxxx Kdump: loaded Tainted: G S 5.15.0-04194-gd852503f7711 #16 RIP: 0010:skb_try_coalesce+0x78b/0x7e0 Code: e8 2a bf 41 ff 44 8b b3 bc 00 00 00 48 8b 7c 24 30 e8 19 c0 41 ff 44 89 f0 48 03 83 c0 00 00 00 48 89 44 24 40 e9 47 fb ff ff <0f> 0b e9 ca fc ff ff 4c 8d 70 ff 48 83 c0 07 48 89 44 24 38 e9 61 RSP: 0018:ffff88881f449688 EFLAGS: 00010282 RAX: 00000000fffffe96 RBX: ffff8881566e4460 RCX: ffffffff82079f7e RDX: 0000000000000003 RSI: dffffc0000000000 RDI: ffff8881566e47b0 RBP: ffff8881566e46e0 R08: ffffed102619235d R09: ffffed102619235d R10: ffff888130c91ae3 R11: ffffed102619235c R12: ffff88881f4498a0 R13: 0000000000000056 R14: 0000000000000009 R15: ffff888130c91ac0 FS: 00007fec2cbb9700(0000) GS:ffff88881f440000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fec1b060d80 CR3: 00000003acf94005 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> tcp_try_coalesce+0xeb/0x290 ? tcp_parse_options+0x610/0x610 ? mark_held_locks+0x79/0xa0 tcp_queue_rcv+0x69/0x2f0 tcp_rcv_established+0xa49/0xd40 ? tcp_data_queue+0x18a0/0x18a0 tcp_v6_do_rcv+0x1c9/0x880 ? rt6_mtu_change_route+0x100/0x100 tcp_v6_rcv+0x1624/0x1830 Signed-off-by: Jakub Kicinski <[email protected]>
1 parent 8a33dcc commit 84882cf

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6 files changed

+9
-53
lines changed

6 files changed

+9
-53
lines changed

‎include/linux/skbuff.h

Lines changed: 1 addition & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -454,15 +454,9 @@ enum {
454454
* all frags to avoid possible bad checksum
455455
*/
456456
SKBFL_SHARED_FRAG = BIT(1),
457-
458-
/* segment contains only zerocopy data and should not be
459-
* charged to the kernel memory.
460-
*/
461-
SKBFL_PURE_ZEROCOPY = BIT(2),
462457
};
463458

464459
#define SKBFL_ZEROCOPY_FRAG (SKBFL_ZEROCOPY_ENABLE | SKBFL_SHARED_FRAG)
465-
#define SKBFL_ALL_ZEROCOPY (SKBFL_ZEROCOPY_FRAG | SKBFL_PURE_ZEROCOPY)
466460

467461
/*
468462
* The callback notifies userspace to release buffers when skb DMA is done in
@@ -1470,17 +1464,6 @@ static inline struct ubuf_info *skb_zcopy(struct sk_buff *skb)
14701464
return is_zcopy ? skb_uarg(skb) : NULL;
14711465
}
14721466

1473-
static inline bool skb_zcopy_pure(const struct sk_buff *skb)
1474-
{
1475-
return skb_shinfo(skb)->flags & SKBFL_PURE_ZEROCOPY;
1476-
}
1477-
1478-
static inline bool skb_pure_zcopy_same(const struct sk_buff *skb1,
1479-
const struct sk_buff *skb2)
1480-
{
1481-
return skb_zcopy_pure(skb1) == skb_zcopy_pure(skb2);
1482-
}
1483-
14841467
static inline void net_zcopy_get(struct ubuf_info *uarg)
14851468
{
14861469
refcount_inc(&uarg->refcnt);
@@ -1545,7 +1528,7 @@ static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy_success)
15451528
if (!skb_zcopy_is_nouarg(skb))
15461529
uarg->callback(skb, uarg, zerocopy_success);
15471530

1548-
skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY;
1531+
skb_shinfo(skb)->flags &= ~SKBFL_ZEROCOPY_FRAG;
15491532
}
15501533
}
15511534

‎include/net/tcp.h

Lines changed: 2 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -293,10 +293,7 @@ static inline bool tcp_out_of_memory(struct sock *sk)
293293
static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
294294
{
295295
sk_wmem_queued_add(sk, -skb->truesize);
296-
if (!skb_zcopy_pure(skb))
297-
sk_mem_uncharge(sk, skb->truesize);
298-
else
299-
sk_mem_uncharge(sk, SKB_TRUESIZE(MAX_TCP_HEADER));
296+
sk_mem_uncharge(sk, skb->truesize);
300297
__kfree_skb(skb);
301298
}
302299

@@ -977,8 +974,7 @@ static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
977974
const struct sk_buff *from)
978975
{
979976
return likely(tcp_skb_can_collapse_to(to) &&
980-
mptcp_skb_can_collapse(to, from) &&
981-
skb_pure_zcopy_same(to, from));
977+
mptcp_skb_can_collapse(to, from));
982978
}
983979

984980
/* Events passed to congestion control interface */

‎net/core/datagram.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -646,8 +646,7 @@ int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb,
646646
skb->truesize += truesize;
647647
if (sk && sk->sk_type == SOCK_STREAM) {
648648
sk_wmem_queued_add(sk, truesize);
649-
if (!skb_zcopy_pure(skb))
650-
sk_mem_charge(sk, truesize);
649+
sk_mem_charge(sk, truesize);
651650
} else {
652651
refcount_add(truesize, &skb->sk->sk_wmem_alloc);
653652
}

‎net/core/skbuff.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3433,9 +3433,8 @@ static inline void skb_split_no_header(struct sk_buff *skb,
34333433
void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
34343434
{
34353435
int pos = skb_headlen(skb);
3436-
const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
34373436

3438-
skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
3437+
skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
34393438
skb_zerocopy_clone(skb1, skb, 0);
34403439
if (len < pos) /* Split line is inside header. */
34413440
skb_split_inside_header(skb, skb1, len, pos);

‎net/ipv4/tcp.c

Lines changed: 2 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -863,7 +863,6 @@ struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
863863
if (likely(skb)) {
864864
bool mem_scheduled;
865865

866-
skb->truesize = SKB_TRUESIZE(size + MAX_TCP_HEADER);
867866
if (force_schedule) {
868867
mem_scheduled = true;
869868
sk_forced_mem_schedule(sk, skb->truesize);
@@ -1320,15 +1319,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
13201319

13211320
copy = min_t(int, copy, pfrag->size - pfrag->offset);
13221321

1323-
/* skb changing from pure zc to mixed, must charge zc */
1324-
if (unlikely(skb_zcopy_pure(skb))) {
1325-
if (!sk_wmem_schedule(sk, skb->data_len))
1326-
goto wait_for_space;
1327-
1328-
sk_mem_charge(sk, skb->data_len);
1329-
skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
1330-
}
1331-
13321322
if (!sk_wmem_schedule(sk, copy))
13331323
goto wait_for_space;
13341324

@@ -1349,16 +1339,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
13491339
}
13501340
pfrag->offset += copy;
13511341
} else {
1352-
/* First append to a fragless skb builds initial
1353-
* pure zerocopy skb
1354-
*/
1355-
if (!skb->len)
1356-
skb_shinfo(skb)->flags |= SKBFL_PURE_ZEROCOPY;
1357-
1358-
if (!skb_zcopy_pure(skb)) {
1359-
if (!sk_wmem_schedule(sk, copy))
1360-
goto wait_for_space;
1361-
}
1342+
if (!sk_wmem_schedule(sk, copy))
1343+
goto wait_for_space;
13621344

13631345
err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg);
13641346
if (err == -EMSGSIZE || err == -EEXIST) {

‎net/ipv4/tcp_output.c

Lines changed: 2 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1677,8 +1677,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
16771677
if (delta_truesize) {
16781678
skb->truesize -= delta_truesize;
16791679
sk_wmem_queued_add(sk, -delta_truesize);
1680-
if (!skb_zcopy_pure(skb))
1681-
sk_mem_uncharge(sk, delta_truesize);
1680+
sk_mem_uncharge(sk, delta_truesize);
16821681
}
16831682

16841683
/* Any change of skb->len requires recalculation of tso factor. */
@@ -2296,9 +2295,7 @@ static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len)
22962295
if (len <= skb->len)
22972296
break;
22982297

2299-
if (unlikely(TCP_SKB_CB(skb)->eor) ||
2300-
tcp_has_tx_tstamp(skb) ||
2301-
!skb_pure_zcopy_same(skb, next))
2298+
if (unlikely(TCP_SKB_CB(skb)->eor) || tcp_has_tx_tstamp(skb))
23022299
return false;
23032300

23042301
len -= skb->len;

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