Date: Sat, 7 Apr 2018 12:55:56 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: Justin Hibbits <chmeeedalf@gmail.com> Cc: Mark Johnston <markj@freebsd.org>, Jeff Roberson <jroberson@jroberson.net>, FreeBSD current <freebsd-current@freebsd.org> Subject: Re: Strange ARC/Swap/CPU on yesterday's -CURRENT Message-ID: <tkrat.282ffd016285f8c7@FreeBSD.org> In-Reply-To: <CAHSQbTA0kgzB6tLV9Zn7gU5wxfURddatekP8Cy9G5hKLkb1ckw@mail.gmail.com> References: <alpine.BSF.2.21.1803111038460.1232@desktop> <20180320070745.GA12880@server.rulingia.com> <2b3db2af-03c7-65ff-25e7-425cfd8815b6@FreeBSD.org> <1fd2b47b-b559-69f8-7e39-665f0f599c8f@FreeBSD.org> <tkrat.9bab32187c0e8d01@FreeBSD.org> <tkrat.11e402b8455bd0fa@FreeBSD.org> <tkrat.7e60fe1978ea51c0@FreeBSD.org> <20180404174949.GA12271@raichu> <tkrat.5960d3aa016999f6@FreeBSD.org> <CAHSQbTBjs=5Nq-QGZftYh8rDwMuCZN7CrsLt0OPPOyzW2V6_Ow@mail.gmail.com> <20180406150814.GB10017@raichu> <CAHSQbTCGmw5-_b1VJn6iotYovfDdPZ6RDC1pT9%2B9J=7%2BGzD=%2Bg@mail.gmail.com> <CAHSQbTA0kgzB6tLV9Zn7gU5wxfURddatekP8Cy9G5hKLkb1ckw@mail.gmail.com>
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On 7 Apr, Justin Hibbits wrote: > On Fri, Apr 6, 2018 at 10:25 AM, Justin Hibbits <chmeeedalf@gmail.com> wrote: >> On Fri, Apr 6, 2018 at 10:08 AM, Mark Johnston <markj@freebsd.org> wrote: >>> On Fri, Apr 06, 2018 at 12:47:14AM +0000, Justin Hibbits wrote: >>>> My powerpc64 embedded machine is virtually unusable since these vm changes. >>>> I tried setting vfs.zfs.arc_free_target as suggested, and that didn't help >>>> at all. Eventually the machine hangs and just gets stuck in vmdaemon, with >>>> many processes in wait channel btalloc. >>> >>> You don't really have the same symptoms that Don is reporting. >> >> Okay. I latched onto the thread because it seemed similar. >> >>> Threads being stuck in btalloc implies a KVA shortage. So: >>> - What do you mean by "stuck in vmdaemon"? >> >> The machine hangs, and my ssh sessions get killed. I can't do >> anything at the console except break into kdb. When I do, the running >> thread is always vmdaemon. >> >>> - Which commits specifically cause problems? Does reverting r329882 fix the >>> hang? >> >> I'll try reverting it and report back. Thankfully I can buildkernel >> successfully on the machine before it hangs. Can't do more than that, >> though. > > I reverted back to r329881, and successfully built world. Updated to > r329882 and it got stuck with processes in btalloc. > > I've seen other reports of r329882 causing problems on powerpc64 as > well, with other bizarre behaviors. I initially missed that this was on powerpc. I believe that arch is a bit odd with characters unsigned by default and arithmentic shifts always being unsigned. Things like that could mess up the algorithm, but I didn't see anything suspicious in the r329882 diff.
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