[Ocfs2-devel] [PATCH v1 2/3] Treewide: Stop corrupting socket's task_frag

[Paolo Abeni]

On Mon, 2022-11-21 at 08:35 -0500, Benjamin Coddington 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.
> 
> CC: Philipp Reisner <philipp.reisner at linbit.com>
> CC: Lars Ellenberg <lars.ellenberg at linbit.com>
> CC: "Christoph Böhmwalder" <christoph.boehmwalder at linbit.com>
> CC: Jens Axboe <axboe at kernel.dk>
> CC: Josef Bacik <josef at toxicpanda.com>
> CC: Keith Busch <kbusch at kernel.org>
> CC: Christoph Hellwig <hch at lst.de>
> CC: Sagi Grimberg <sagi at grimberg.me>
> CC: Lee Duncan <lduncan at suse.com>
> CC: Chris Leech <cleech at redhat.com>
> CC: Mike Christie <michael.christie at oracle.com>
> CC: "James E.J. Bottomley" <jejb at linux.ibm.com>
> CC: "Martin K. Petersen" <martin.petersen at oracle.com>
> CC: Valentina Manea <valentina.manea.m at gmail.com>
> CC: Shuah Khan <shuah at kernel.org>
> CC: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> CC: David Howells <dhowells at redhat.com>
> CC: Marc Dionne <marc.dionne at auristor.com>
> CC: Steve French <sfrench at samba.org>
> CC: Christine Caulfield <ccaulfie at redhat.com>
> CC: David Teigland <teigland at redhat.com>
> CC: Mark Fasheh <mark at fasheh.com>
> CC: Joel Becker <jlbec at evilplan.org>
> CC: Joseph Qi <joseph.qi at linux.alibaba.com>
> CC: Eric Van Hensbergen <ericvh at gmail.com>
> CC: Latchesar Ionkov <lucho at ionkov.net>
> CC: Dominique Martinet <asmadeus at codewreck.org>
> CC: "David S. Miller" <davem at davemloft.net>
> CC: Eric Dumazet <edumazet at google.com>
> CC: Jakub Kicinski <kuba at kernel.org>
> CC: Paolo Abeni <pabeni at redhat.com>
> CC: Ilya Dryomov <idryomov at gmail.com>
> CC: Xiubo Li <xiubli at redhat.com>
> CC: Chuck Lever <chuck.lever at oracle.com>
> CC: Jeff Layton <jlayton at kernel.org>
> CC: Trond Myklebust <trond.myklebust at hammerspace.com>
> CC: Anna Schumaker <anna at kernel.org>
> CC: drbd-dev at lists.linbit.com
> CC: linux-block at vger.kernel.org
> CC: linux-kernel at vger.kernel.org
> CC: nbd at other.debian.org
> CC: linux-nvme at lists.infradead.org
> CC: open-iscsi at googlegroups.com
> CC: linux-scsi at vger.kernel.org
> CC: linux-usb at vger.kernel.org
> CC: linux-afs at lists.infradead.org
> CC: linux-cifs at vger.kernel.org
> CC: samba-technical at lists.samba.org
> CC: cluster-devel at redhat.com
> CC: ocfs2-devel at oss.oracle.com
> CC: v9fs-developer at lists.sourceforge.net
> CC: netdev at vger.kernel.org
> CC: ceph-devel at vger.kernel.org
> CC: linux-nfs at vger.kernel.org
> 
> Suggested-by: Guillaume Nault <gnault at redhat.com>
> Signed-off-by: Benjamin Coddington <bcodding at redhat.com>

I think this is the most feasible way out of the existing issue, and I
think this patchset should go via the networking tree, targeting the
Linux 6.2.

If someone has disagreement with the above, please speak! 

Thanks,

Paolo