From a1a75aa9be2c133dd1372a08eeb6a92c31688df7 Mon Sep 17 00:00:00 2001 From: Ben Gamari Date: Wed, 25 Nov 2020 10:54:31 -0500 Subject: rts: Allocate MBlocks with MAP_TOP_DOWN on Windows As noted in #18991, we would previously allocate heap in low memory. Due to this the linker, which typically *needs* low memory, would end up competing with the heap. In longer builds we end up running out of low memory entirely, leading to linking failures. --- rts/win32/OSMem.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/rts/win32/OSMem.c b/rts/win32/OSMem.c index dd53f4d589..138660a879 100644 --- a/rts/win32/OSMem.c +++ b/rts/win32/OSMem.c @@ -50,8 +50,11 @@ allocNew(uint32_t n) { alloc_rec* rec; rec = (alloc_rec*)stgMallocBytes(sizeof(alloc_rec),"getMBlocks: allocNew"); rec->size = ((W_)n+1)*MBLOCK_SIZE; + // N.B. We use MEM_TOP_DOWN here to ensure that we leave the bottom of the + // address space available for the linker and libraries, which in general + // want to live in low memory. See #18991. rec->base = - VirtualAlloc(NULL, rec->size, MEM_RESERVE, PAGE_READWRITE); + VirtualAlloc(NULL, rec->size, MEM_RESERVE | MEM_TOP_DOWN, PAGE_READWRITE); if(rec->base==0) { stgFree((void*)rec); rec=0; -- cgit v1.2.1