| commit | c30ee2656adc3ba725baf6f37461a79dda765f9d | |
| author | Douglas Katzman <dougk@google.com> | |
| Sat, 10 Dec 2016 15:44:09 +0000 (10 10:44 -0500) | ||
| committer | Douglas Katzman <dougk@google.com> | |
| Sat, 10 Dec 2016 15:52:09 +0000 (10 10:52 -0500) | ||
| tree | 9cdd693a43dc253d913319bc3db8cc874ea73383 | treesnapshot (tar.gz zip) |
| parent | 84b723e8c4bd309a58dc8e677f9c6f59ea326dce | commitdiff |
Fix two problems in mark & sweep GC.
- Fencepost bug in computing 'max_used_varyobj_page' if the final page
has no object header on it (so its generation mask is 0).
- Flip the order of operations in the page fault handler.
In the order as it was, if GC happened in between setting the dirty bit
and making a page writable, then the GC might simply clear the bit,
as no write has actually occurred yet, only to resume at the system call
which unprotects the page. This made a writable page not marked dirty.
- Fencepost bug in computing 'max_used_varyobj_page' if the final page
has no object header on it (so its generation mask is 0).
- Flip the order of operations in the page fault handler.
In the order as it was, if GC happened in between setting the dirty bit
and making a page writable, then the GC might simply clear the bit,
as no write has actually occurred yet, only to resume at the system call
which unprotects the page. This made a writable page not marked dirty.
| src/runtime/marknsweepgc.c | diffblobblamehistory |