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98123866fc
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@linbit.com> CC: Lars Ellenberg <lars.ellenberg@linbit.com> CC: "Christoph Böhmwalder" <christoph.boehmwalder@linbit.com> CC: Jens Axboe <axboe@kernel.dk> CC: Josef Bacik <josef@toxicpanda.com> CC: Keith Busch <kbusch@kernel.org> CC: Christoph Hellwig <hch@lst.de> CC: Sagi Grimberg <sagi@grimberg.me> CC: Lee Duncan <lduncan@suse.com> CC: Chris Leech <cleech@redhat.com> CC: Mike Christie <michael.christie@oracle.com> CC: "James E.J. Bottomley" <jejb@linux.ibm.com> CC: "Martin K. Petersen" <martin.petersen@oracle.com> CC: Valentina Manea <valentina.manea.m@gmail.com> CC: Shuah Khan <shuah@kernel.org> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CC: David Howells <dhowells@redhat.com> CC: Marc Dionne <marc.dionne@auristor.com> CC: Steve French <sfrench@samba.org> CC: Christine Caulfield <ccaulfie@redhat.com> CC: David Teigland <teigland@redhat.com> CC: Mark Fasheh <mark@fasheh.com> CC: Joel Becker <jlbec@evilplan.org> CC: Joseph Qi <joseph.qi@linux.alibaba.com> CC: Eric Van Hensbergen <ericvh@gmail.com> CC: Latchesar Ionkov <lucho@ionkov.net> CC: Dominique Martinet <asmadeus@codewreck.org> CC: Ilya Dryomov <idryomov@gmail.com> CC: Xiubo Li <xiubli@redhat.com> CC: Chuck Lever <chuck.lever@oracle.com> CC: Jeff Layton <jlayton@kernel.org> CC: Trond Myklebust <trond.myklebust@hammerspace.com> CC: Anna Schumaker <anna@kernel.org> CC: Steffen Klassert <steffen.klassert@secunet.com> CC: Herbert Xu <herbert@gondor.apana.org.au> Suggested-by: Guillaume Nault <gnault@redhat.com> Signed-off-by: Benjamin Coddington <bcodding@redhat.com> Reviewed-by: Guillaume Nault <gnault@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.