Subject: Re: [PATCH net v4 0/5] xsk: fix meta and publish of cq issues

From: Maciej Fijalkowski <[email-masked]>
Date: Thu, 21 May 2026 16:24:01 +0200

On Thu, May 21, 2026 at 09:07:30PM +0800, Jason Xing wrote:
> On Thu, May 21, 2026 at 9:00 PM Maciej Fijalkowski
> <[email-masked]> wrote:
> >
> > On Thu, May 21, 2026 at 08:41:08PM +0800, Jason Xing wrote:
> > > On Thu, May 21, 2026 at 8:24 PM Maciej Fijalkowski
> > > <[email-masked]> wrote:
> > > >
> > > > On Wed, May 20, 2026 at 08:42:39AM +0800, Jason Xing wrote:
> > > > > From: Jason Xing <[email-masked]>
> > > > >
> > > > > The series is the product of previous review from sashiko[1].
> > > > >
> > > > > 1) META
> > > > > patch 1: address TOCTOU around metadata.
> > > > >
> > > > > 2) PUBLISH of CQ
> > > > > patch 2: make sure xsk_addr->addrs[] can be published to cq when
> > > > >          overflow occurs.
> > > > > patch 3: keep cleaning up the continuation descs (more than 17) and
> > > > >          publish its address when overflow occurs.
> > > > > patch 4: like patch 3, but only handles the invalid descs cases.
> > > > >
> > > > > [1]: https://lore.kernel.org/all/[email-masked]/
> > > > >
> > > > > ---
> > > > > V4
> > > > > Link: https://lore.kernel.org/all/[email-masked]/
> > > > > 1. correct the description of xmit path in patch 3 (sashiko)
> > > > > 2. move set logic into xmit path in patch 3 (Stan)
> > > > >
> > > > > V3
> > > > > Link: https://lore.kernel.org/all/[email-masked]/
> > > > > 1. avoid breaking previous usage of sendto, and siliently handle
> > > > > overflow case (Stan, sashiko)
> > > > > 2. add one particular exception process in patch 4 (sashiko)
> > > > > 3. adjust the selftest to make sure it passes in either virutal or
> > > > > physical machines, which includes add usleep to support physical machine.
> > > > >
> > > > > V2
> > > > > Link: https://lore.kernel.org/all/[email-masked]/
> > > > > 1. adjust selftests (Jakub)
> > > > > 2. add READ_ONCE in patch 1 (Stan)
> > > >
> > > > FWIW I still get test failures (yes with patch 5 applied). PTAL.
> > >
> > > Thanks for the test. But I've tried with ixgbe driver...
> > >
> > > I noticed there are some flaky tests which have nothing to do with the
> > > series. Can you confirm that it's not caused because of the series?
> >
> > That explains the different results as i am using i40e/ice which have
> > multi-buffer support whereas ixgbe does not even support mbuf at XDP.
> > Broken tests are from mbuf cases.
> 
> That's weird. I never expected the failed tests to be about multi-buffer.
> 
> Are they the same as the output you attached last time? Or something
> new? Could you please share it so that I can investigate the root
> cause?

# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 21 FAIL: SKB ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 33 FAIL: SKB UNALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 57 FAIL: DRV ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 69 FAIL: DRV UNALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 93 FAIL: ZC ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [11], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
---------------------------------------
not ok 94 FAIL: ZC TOO_MANY_FRAGS
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 105 FAIL: ZC UNALIGNED_INV_DESC_MULTI_BUFF

# 4 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:96 fail:8 xfail:0 xpass:0 skip:4 error:0
XSK_SELFTESTS_ens259f1np1_SOFTIRQ: [ FAIL ]
1..108
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 21 FAIL: SKB BUSY-POLL ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 33 FAIL: SKB BUSY-POLL UNALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 57 FAIL: DRV BUSY-POLL ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 69 FAIL: DRV BUSY-POLL UNALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 93 FAIL: ZC BUSY-POLL ALIGNED_INV_DESC_MULTI_BUFF
# [is_frag_valid] expected pkt_nb [11], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
---------------------------------------
# [is_frag_valid] expected pkt_nb [10], got pkt_nb [0]
# DEBUG>> L2: dst mac: # 55# 44# 33# 22# 11# 01# 
DEBUG>> L2: src mac: # 55# 44# 33# 22# 11# 00# 
DEBUG>> L5: seqnum: # 0:0 # 0:1 # 0:2 # 0:3 # 0:4 # 0:5 # 0:6 # 0:7 # 0:8 # 0:9 # 0:10 # 0:11 # 0:0 # 0:0 # 0:0 # 0:0 # ....# 
.... # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 0:0 # 
---------------------------------------
not ok 105 FAIL: ZC BUSY-POLL UNALIGNED_INV_DESC_MULTI_BUFF

# 4 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:96 fail:8 xfail:0 xpass:0 skip:4 error:0
XSK_SELFTESTS_ens259f1np1_BUSY_POLL: [ FAIL ]

Summary:
XSK_SELFTESTS_ens259f1np1_SOFTIRQ: [ FAIL ]
XSK_SELFTESTS_ens259f1np1_BUSY_POLL: [ FAIL ]

> 
> Thanks,
> Jason
> 
> >
> > >
> > > Thanks,
> > > Jason
> > >
> > >
> > > >
> > > > >
> > > > >
> > > > > Jason Xing (5):
> > > > >   xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()
> > > > >   xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx
> > > > >   xsk: drain continuation descs after overflow in xsk_build_skb()
> > > > >   xsk: drain continuation descs on invalid descriptor in
> > > > >     __xsk_generic_xmit()
> > > > >   selftests/xsk: drain CQ to wait for TX completion
> > > > >
> > > > >  include/net/xdp_sock.h                        |  1 +
> > > > >  net/xdp/xsk.c                                 | 44 +++++++++++++----
> > > > >  .../selftests/bpf/prog_tests/test_xsk.c       | 48 +++++++++++--------
> > > > >  3 files changed, 63 insertions(+), 30 deletions(-)
> > > > >
> > > > > --
> > > > > 2.43.7
> > > > >