From 1b6ea4900b855ac5ff84188751758fb3f0692f62 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 3 Oct 2007 20:42:45 -0700 Subject: [PATCH] vcompound: Virtual Compound page allocation from interrupt context. In an interrupt context we cannot wait for the vmlist_lock in __get_vm_area_node(). So use a trylock instead. If the trylock fails then the atomic allocation will fail and subsequently be retried. This only works because the flush_cache_vunmap in use for allocation is never performing any IPIs in contrast to flush_tlb_... in use for freeing. flush_cache_vunmap is only used on architectures with a virtually mapped cache (xtensa, pa-risc). [Note: Nick Piggin is working on a scheme to make this simpler by no longer requiring flushes] Signed-off-by: Christoph Lameter --- mm/vmalloc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) Index: linux-2.6/mm/vmalloc.c =================================================================== --- linux-2.6.orig/mm/vmalloc.c 2008-02-16 18:49:20.000000000 -0800 +++ linux-2.6/mm/vmalloc.c 2008-02-16 18:56:46.000000000 -0800 @@ -215,7 +215,6 @@ static struct vm_struct *__get_vm_area_n unsigned long align = 1; unsigned long addr; - BUG_ON(in_interrupt()); if (flags & VM_IOREMAP) { int bit = fls(size); @@ -241,7 +240,14 @@ static struct vm_struct *__get_vm_area_n */ size += PAGE_SIZE; - write_lock(&vmlist_lock); + if (gfp_mask & __GFP_WAIT) + write_lock(&vmlist_lock); + else { + if (!write_trylock(&vmlist_lock)) { + kfree(area); + return NULL; + } + } for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) { if ((unsigned long)tmp->addr < addr) { if((unsigned long)tmp->addr + tmp->size >= addr)