Date: Sun, 25 Mar 2001 10:18:47 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Kirk McKusick <mckusick@mckusick.com> Cc: Jeroen Ruigrok/Asmodai <asmodai@wxs.nl>, Peter Wemm <peter@FreeBSD.ORG>, Paul Saab <ps@FreeBSD.ORG>, Soeren Schmidt <sos@FreeBSD.ORG>, current@FreeBSD.ORG Subject: Re: vm page panic Message-ID: <200103251818.f2PIIlp11246@earth.backplane.com> References: <200103251514.HAA04116@beastie.mckusick.com>
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: Hi guys,
:
: ok, sources cvsupped yesterday afternoon, just before my ffs_alloc.c
: commit [which I did, obviously, add myself locally].
:
: Box had been running for a while when all of a sudden it got into a
: panic:
:
: vm_page_alloc: free/cache page 0xc0776fa4 was dirty
:
: a trace in ddb shows:
:
: allocbuf()
: getblk()
: ffs_balloc()
: ffs_write()
: vn_rdwr()
: elf_coredump()
: coredump()
This particular panic will have a delayed effect, so the trace probably
isn't the problem. Something occured some period of time prior that
caused a (probably cache) page to be marked dirty. Then later when
vm_page_alloc() tries to reuse the page it notices that it's dirty when
it shouldn't be.
I have not seen this panic literaly for years - there was a bug in
John Dyson's original code that could cause it but it was fixed a very
long time ago. So I'm guessing that the panic is a side effect of a
newly introduced bug somewhere in current. Possibly a race of some sort
with the mutex/threading/interrupt code, but I don't know.
-Matt
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