Date: Sat, 26 Mar 2022 04:03:46 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: John Baldwin <jhb@FreeBSD.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org> Subject: Re: ktrace on NFSroot failing? Message-ID: <YT2PR01MB973039BE3072ED3F94CFE141DD1B9@YT2PR01MB9730.CANPRD01.PROD.OUTLOOK.COM> In-Reply-To: <YT2PR01MB97308688D7ACB6072A20DBE8DD1B9@YT2PR01MB9730.CANPRD01.PROD.OUTLOOK.COM> References: <alpine.BSF.2.00.2203101514090.68830@ai.fobar.qr> <CAGudoHGCOVQy7CVySkNKey0QYi2zqO8UqBUcACzmWH4B-ZpsuQ@mail.gmail.com> <70135754-84c2-b642-5641-0721e0b4690d@FreeBSD.org> <YT2PR01MB97308688D7ACB6072A20DBE8DD1B9@YT2PR01MB9730.CANPRD01.PROD.OUTLOOK.COM>
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[-- Attachment #1 --] Rick Macklem <rmacklem@uoguelph.ca> wrote: > John Baldwin <jhb@FreeBSD.org> wrote: > > On 3/10/22 8:14 AM, Mateusz Guzik wrote: > > > On 3/10/22, Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net> wrote: > > >> Hi, > > >> > > >> I am having a weird issue with ktrace on an nfsroot machine: > > >> > > >> root:/tmp # ktrace sleep 1 > > >> root:/tmp # kdump > > >> -559038242 Events dropped. > > >> kdump: bogus length 0xdeadc0de > > >> > > >> Anyone seen something like this before? > > >> > > > > > > I just did a quick check and it definitely fails on nfs mounts: > > > # ktrace pwd > > > /root/mjg > > > # kdump > > > -559038242 Events dropped. > > > kdump: bogus length 0xdeadc0de > > > > > > I don't have time to look into it this week though. > > > > Possibly related: core dumps are no longer working for me on NFS > > mounts. I get a 0 byte foo.core instead of a valid core dump. > I just tried a core dump for a kernel built from main sources as of > to-day and it worked ok. > > However my userland is several months old and I can't easily upgrade > it for now. > > There was a recent ZFS problem that found its way into 13.0-p8 that > I'm pretty sure is fixed now. If you had a fairly recent server exporting > ZFS, that *might* explain it? > > In particular, an NFSroot uses NFSv3 and nothing has changed for > NFSv3 in a looonnggg time. Oops, I did make a change that affected NFSv3 as well as NFSv4. Last December I committed a path to head that made IO_APPEND writes use nfs_directio_write() and avoid the buffer cache. Turns out nfs_directio_write() only worked for UIO_USERSPACE. The attached trivial patch fixes ktrace for me. I have no idea if core dumping ever does IO_APPEND VOP_WRITE()s? Please test the attached patch. Thanks, rick rick -- John Baldwin [-- Attachment #2 --] --- sys/fs/nfsclient/nfs_clbio.c.sav 2022-03-25 19:36:58.381558000 -0700 +++ sys/fs/nfsclient/nfs_clbio.c 2022-03-25 19:44:15.386469000 -0700 @@ -780,7 +780,7 @@ do_sync: uio.uio_iovcnt = 1; uio.uio_offset = uiop->uio_offset; uio.uio_resid = size; - uio.uio_segflg = UIO_USERSPACE; + uio.uio_segflg = uiop->uio_segflg; uio.uio_rw = UIO_WRITE; uio.uio_td = td; iomode = NFSWRITE_FILESYNC;help
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