diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2022-12-19 17:28:51 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-12-19 17:28:52 -0800 |
| commit | 918fb1aaa25812a277ab469679df17f45ce92313 (patch) | |
| tree | dedc1398193582d8d52ad9142d95f5b16bd5d50c /include | |
| parent | b389a902dd5be4ece505a2e0463b9b034de04bf5 (diff) | |
| parent | 08f65892c5ee15806dce7259e06c384b8cd768d7 (diff) | |
Merge branch 'stop-corrupting-socket-s-task_frag'
Benjamin Coddington says:
====================
Stop corrupting socket's task_frag
The networking code uses flags in sk_allocation to determine if it can use
current->task_frag, however in-kernel users of sockets may stop setting
sk_allocation when they convert to the preferred memalloc_nofs_save/restore,
as SUNRPC has done in commit a1231fda7e94 ("SUNRPC: Set memalloc_nofs_save()
on all rpciod/xprtiod jobs").
This will cause corruption in current->task_frag when recursing into the
network layer for those subsystems during page fault or reclaim. The
corruption is difficult to diagnose because stack traces may not contain the
offending subsystem at all. The corruption is unlikely to show up in
testing because it requires memory pressure, and so subsystems that
convert to memalloc_nofs_save/restore are likely to continue to run into
this issue.
Previous reports and proposed fixes:
https://lore.kernel.org/netdev/96a18bd00cbc6cb554603cc0d6ef1c551965b078.1663762494.git.gnault@redhat.com/
https://lore.kernel.org/netdev/b4d8cb09c913d3e34f853736f3f5628abfd7f4b6.1656699567.git.gnault@redhat.com/
https://lore.kernel.org/linux-nfs/de6d99321d1dcaa2ad456b92b3680aa77c07a747.1665401788.git.gnault@redhat.com/
Guilluame Nault has done all of the hard work tracking this problem down and
finding the best fix for this issue. I'm just taking a turn posting another
fix.
====================
Link: https://lore.kernel.org/r/cover.1671194454.git.bcodding@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/sock.h | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index ecea3dcc2217..dcd72e6285b2 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -318,6 +318,9 @@ struct sk_filter; * @sk_stamp: time stamp of last packet received * @sk_stamp_seq: lock for accessing sk_stamp on 32 bit architectures only * @sk_tsflags: SO_TIMESTAMPING flags + * @sk_use_task_frag: allow sk_page_frag() to use current->task_frag. + * Sockets that can be used under memory reclaim should + * set this to false. * @sk_bind_phc: SO_TIMESTAMPING bind PHC index of PTP virtual clock * for timestamping * @sk_tskey: counter to disambiguate concurrent tstamp requests @@ -512,6 +515,7 @@ struct sock { u8 sk_txtime_deadline_mode : 1, sk_txtime_report_errors : 1, sk_txtime_unused : 6; + bool sk_use_task_frag; struct socket *sk_socket; void *sk_user_data; @@ -2560,16 +2564,14 @@ static inline void sk_stream_moderate_sndbuf(struct sock *sk) * Both direct reclaim and page faults can nest inside other * socket operations and end up recursing into sk_page_frag() * while it's already in use: explicitly avoid task page_frag - * usage if the caller is potentially doing any of them. - * This assumes that page fault handlers use the GFP_NOFS flags. + * when users disable sk_use_task_frag. * * Return: a per task page_frag if context allows that, * otherwise a per socket one. */ static inline struct page_frag *sk_page_frag(struct sock *sk) { - if ((sk->sk_allocation & (__GFP_DIRECT_RECLAIM | __GFP_MEMALLOC | __GFP_FS)) == - (__GFP_DIRECT_RECLAIM | __GFP_FS)) + if (sk->sk_use_task_frag) return ¤t->task_frag; return &sk->sk_frag; |