From: Guillaume Nault <gnault@redhat•com>
To: Eric Dumazet <edumazet@google•com>
Cc: "Benjamin Coddington" <bcodding@redhat•com>,
"Jakub Kicinski" <kuba@kernel•org>,
"Paolo Abeni" <pabeni@redhat•com>,
"David S. Miller" <davem@davemloft•net>,
"Philipp Reisner" <philipp.reisner@linbit•com>,
"Lars Ellenberg" <lars.ellenberg@linbit•com>,
"Christoph Böhmwalder" <christoph.boehmwalder@linbit•com>,
"Jens Axboe" <axboe@kernel•dk>,
"Josef Bacik" <josef@toxicpanda•com>,
"Keith Busch" <kbusch@kernel•org>,
"Christoph Hellwig" <hch@lst•de>,
"Sagi Grimberg" <sagi@grimberg•me>,
"Lee Duncan" <lduncan@suse•com>,
"Chris Leech" <cleech@redhat•com>,
"Mike Christie" <michael.christie@oracle•com>,
"James E.J. Bottomley" <jejb@linux•ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle•com>,
"Valentina Manea" <valentina.manea.m@gmail•com>,
"Shuah Khan" <shuah@kernel•org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation•org>,
"David Howells" <dhowells@redhat•com>,
"Marc Dionne" <marc.dionne@auristor•com>,
"Steve French" <sfrench@samba•org>,
"Christine Caulfield" <ccaulfie@redhat•com>,
"David Teigland" <teigland@redhat•com>,
"Mark Fasheh" <mark@fasheh•com>,
"Joel Becker" <jlbec@evilplan•org>,
"Joseph Qi" <joseph.qi@linux•alibaba.com>,
"Eric Van Hensbergen" <ericvh@gmail•com>,
"Latchesar Ionkov" <lucho@ionkov•net>,
"Dominique Martinet" <asmadeus@codewreck•org>,
"Ilya Dryomov" <idryomov@gmail•com>,
"Xiubo Li" <xiubli@redhat•com>,
"Chuck Lever" <chuck.lever@oracle•com>,
"Jeff Layton" <jlayton@kernel•org>,
"Trond Myklebust" <trond.myklebust@hammerspace•com>,
"Anna Schumaker" <anna@kernel•org>,
"Steffen Klassert" <steffen.klassert@secunet•com>,
"Herbert Xu" <herbert@gondor•apana.org.au>,
netdev@vger•kernel.org
Subject: Re: [PATCH net v4 2/3] Treewide: Stop corrupting socket's task_frag
Date: Tue, 3 Jan 2023 16:14:17 +0100 [thread overview]
Message-ID: <Y7RGSbWX0L4EoA8W@debian> (raw)
In-Reply-To: <CANn89iKik8uMO6=ztufPwYdg1qRPsxToz0Nu-uaZWkE63bKSUQ@mail.gmail.com>
On Tue, Jan 03, 2023 at 03:26:27PM +0100, Eric Dumazet wrote:
> On Fri, Dec 16, 2022 at 1:45 PM Benjamin Coddington <bcodding@redhat•com> wrote:
> >
> > Since moving to memalloc_nofs_save/restore, SUNRPC has stopped setting the
> > GFP_NOIO flag on sk_allocation which the networking system uses to decide
> > when it is safe to use current->task_frag. The results of this are
> > unexpected corruption in task_frag when SUNRPC is involved in memory
> > reclaim.
> >
> > The corruption can be seen in crashes, but the root cause is often
> > difficult to ascertain as a crashing machine's stack trace will have no
> > evidence of being near NFS or SUNRPC code. I believe this problem to
> > be much more pervasive than reports to the community may indicate.
> >
> > Fix this by having kernel users of sockets that may corrupt task_frag due
> > to reclaim set sk_use_task_frag = false. Preemptively correcting this
> > situation for users that still set sk_allocation allows them to convert to
> > memalloc_nofs_save/restore without the same unexpected corruptions that are
> > sure to follow, unlikely to show up in testing, and difficult to bisect.
> >
>
> I am back from PTO.
>
> It seems inet_ctl_sock_create() has been forgotten.
>
> Without following fix, ICMP messages sent from softirq would corrupt
> innocent thread task_frag.
I didn't consider setting ->sk_use_task_frag on ICMP sockets as my
understanding was that only TCP and ip_append_data() could eventually
call sk_page_frag(). Therefore, I didn't see how ICMP sockets could be
affected. Did I miss something?
> (I will submit this patch formally a bit later today)
>
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index ab4a06be489b5d410cec603bf56248d31dbc90dd..6c0ec27899431eb56e2f9d0c3a936b77f44ccaca
> 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1665,6 +1665,7 @@ int inet_ctl_sock_create(struct sock **sk,
> unsigned short family,
> if (rc == 0) {
> *sk = sock->sk;
> (*sk)->sk_allocation = GFP_ATOMIC;
> + (*sk)->sk_use_task_frag = false;
> /*
> * Unhash it so that IP input processing does not even see it,
> * we do not wish this socket to see incoming packets.
>
next prev parent reply other threads:[~2023-01-03 15:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-16 12:45 [PATCH net v4 0/3] Stop corrupting socket's task_frag Benjamin Coddington
2022-12-16 12:45 ` [PATCH net v4 1/3] net: Introduce sk_use_task_frag in struct sock Benjamin Coddington
2022-12-16 12:45 ` [PATCH net v4 2/3] Treewide: Stop corrupting socket's task_frag Benjamin Coddington
2023-01-03 14:26 ` Eric Dumazet
2023-01-03 15:14 ` Guillaume Nault [this message]
2023-01-03 16:10 ` Eric Dumazet
2023-01-03 22:37 ` Guillaume Nault
2022-12-16 12:45 ` [PATCH net v4 3/3] net: simplify sk_page_frag Benjamin Coddington
2022-12-20 2:00 ` [PATCH net v4 0/3] Stop corrupting socket's task_frag patchwork-bot+netdevbpf
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