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[Bug go/60931] libgo has issues when page size is not 4k
- From: "ian at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 25 Apr 2014 04:29:39 +0000
- Subject: [Bug go/60931] libgo has issues when page size is not 4k
- Auto-submitted: auto-generated
- References: <bug-60931-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60931
--- Comment #9 from ian at gcc dot gnu.org <ian at gcc dot gnu.org> ---
Author: ian
Date: Fri Apr 25 04:29:07 2014
New Revision: 209777
URL: http://gcc.gnu.org/viewcvs?rev=209777&root=gcc&view=rev
Log:
PR go/60931
runtime: Fix garbage collector issue with non 4kB system page size
The go garbage collector tracks memory in terms of 4kB pages.
Most of the code checks getpagesize() at runtime and does the
right thing.
On a 64kB ppc64 box I see SEGVs in long running processes
which has been diagnosed as a bug in scavengelist.
scavengelist does a madvise(MADV_DONTNEED) without rounding
the arguments to the system page size. A strace of one of the
failures shows the problem:
madvise(0xc211030000, 4096, MADV_DONTNEED) = 0
The kernel rounds the length up to 64kB and we mark 60kB of
valid data as no longer needed.
Round start up to a system page and end down before calling
madvise.
Modified:
trunk/libgo/runtime/mheap.c