From 29e0307185ea98d262e0fca4c5a72503634ebf5b Mon Sep 17 00:00:00 2001 From: Ben Gamari Date: Wed, 17 Nov 2021 12:08:57 -0500 Subject: rts: Ensure that markCAFs marks object code Previously `markCAFs` would only evacuate CAFs' indirectees. This would allow reachable object code to be unloaded by the linker as `evacuate` may never be called on the CAF itself, despite it being reachable via the `{dyn,revertible}_caf_list`s. To fix this we teach `markCAFs` to explicit call `markObjectCode`, ensuring that the linker is aware of objects reachable via the CAF lists. Fixes #20649. --- rts/sm/GCAux.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'rts') diff --git a/rts/sm/GCAux.c b/rts/sm/GCAux.c index f0e18a5ca5..41c24634c2 100644 --- a/rts/sm/GCAux.c +++ b/rts/sm/GCAux.c @@ -11,6 +11,7 @@ #include "Rts.h" #include "GC.h" +#include "CheckUnload.h" #include "Storage.h" #include "Compact.h" #include "Task.h" @@ -145,20 +146,26 @@ revertCAFs( void ) void markCAFs (evac_fn evac, void *user) { - StgIndStatic *c; - - for (c = dyn_caf_list; + /* N.B. We must both ensure that the indirectee is + * evacuated and that we let the linker know that the CAF + * itself is still reachable, lest it be collected (see + * #20649). + */ + for (StgIndStatic *c = dyn_caf_list; ((StgWord) c | STATIC_FLAG_LIST) != (StgWord)END_OF_CAF_LIST; c = (StgIndStatic *)c->static_link) { c = (StgIndStatic *)UNTAG_STATIC_LIST_PTR(c); evac(user, &c->indirectee); + markObjectCode(c); } - for (c = revertible_caf_list; + + for (StgIndStatic *c = revertible_caf_list; ((StgWord) c | STATIC_FLAG_LIST) != (StgWord)END_OF_CAF_LIST; c = (StgIndStatic *)c->static_link) { c = (StgIndStatic *)UNTAG_STATIC_LIST_PTR(c); evac(user, &c->indirectee); + markObjectCode(c); } } -- cgit v1.2.1