While figuring out some things related to memory management, I
stumbled upon a line in MonetDB/src/gdk/gdk_posix.mx which I don't
fully understand:
munmap(p + oldsize, oldsize - newsize);
..which is called from MT_vmrealloc when the old size is larger than
the new size. This would unmap a region as large as the size
difference between both sizes, but after the currently mapped region
[p; p + oldsize[ (which is probably not mapped, or is mapped to
something unrelated). The attached patch changes this behavior so the
resulting mapped region will be [p; p + newsize[, with the now
unneeded [p + newsize; p + oldsize[ region being unmapped (which is a
behavior I find more intuitive).
Please review and use as it fits.
Best regards,
Isidor Zeuner
diff -uNr MonetDB.orig/src/gdk/gdk_posix.mx MonetDB/src/gdk/gdk_posix.mx
--- MonetDB.orig/src/gdk/gdk_posix.mx
+++ MonetDB/src/gdk/gdk_posix.mx
@@ -2078,7 +2078,7 @@
}
if (oldsize > newsize) {
- munmap(p + oldsize, oldsize - newsize);
+ munmap(p + newsize, oldsize - newsize);
} else if (oldsize < newsize) {
if (newsize < oldmaxsize) {
MMAP_OPEN_DEV_ZERO;
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