Date: Tue, 9 Jun 2020 08:53:09 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Guido Falsi <mad@madpilot.net>, freebsd-fs@freebsd.org Subject: Re: ZFS panic on boot (head) Message-ID: <5c6933c3-7996-694e-91e2-3dda125926e7@FreeBSD.org> In-Reply-To: <8a092b2f-ae13-ef3a-0086-9d4aaaf8466b@madpilot.net> References: <8a092b2f-ae13-ef3a-0086-9d4aaaf8466b@madpilot.net>
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On 08/06/2020 21:20, Guido Falsi via freebsd-fs wrote: > Hi, > > On a laptop running head r361728, after a normal reboot I'm > experiencing an had panic every boot. > > Booting a kernel with kdb I get: > > panic: Solaris(panic): zfs: allocating allocated > segment(offset=433818959872 size=4096) of (offset=433818021200 size=32768) > > I can provide a screenshot of the stack trace if required. > > Is there a way to recover? Or should I simply reinstall the machine? > > What is actually happened? Maybe a disk data error? (it's a laptop with > only one disk) > > Or something misbehaved in ZFS? > > Thanks in advance for any information/help. What you see is inconsistent information in a space map. There are two elements that describe overlapping ranges of disk space. That is something that must never happen. I do not know how that can be repaired, the safest solution is to copy / restore the data to a fresh pool. As to why, this could be a result of a bug in ZFS. If you google for the panic messages (sans concrete numbers) you can find some bugs that were fixed in the past. Also, and it once happened to me, it could be a hardware problem. I used non-ECC memory, (at least) one bit got flipped and it was a bit describing a space map entry. After the corruption the good entry turned into a conflicting entry. A disk error can probably be ruled out. First, ZFS stores 3 copies of all important metadata including space maps, so all three would have to be corrupted. Second, even if all copies were corrupted then you would get a checksum error (this is ZFS). -- Andriy Gapon
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