From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <49010D41.1080305@goop.org> Date: Thu, 23 Oct 2008 16:48:17 -0700 From: Jeremy Fitzhardinge MIME-Version: 1.0 Subject: vm_unmap_aliases and Xen Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Linux Kernel Mailing List , Linux Memory Management List List-ID: I've been having a few problems with Xen, I suspect as a result of the lazy unmapping in vmalloc.c. One immediate one is that vm_unmap_aliases() will oops if you call it before vmalloc_init() is called, which can happen in the Xen case. RFC patch below. But the bigger problem I'm seeing is that despite calling vm_unmap_aliases() at the pertinent places, I'm still seeing errors resulting from stray aliases. Is it possible that vm_unmap_aliases() could be missing some, or not completely synchronous? Subject: vmap: cope with vm_unmap_aliases before vmalloc_init() Xen can end up calling vm_unmap_aliases() before vmalloc_init() has been called. In this case its safe to make it a simple no-op. Signed-off-by: Jeremy Fitzhardinge diff -r 42c8b29f7ccf mm/vmalloc.c --- a/mm/vmalloc.c Wed Oct 22 12:43:39 2008 -0700 +++ b/mm/vmalloc.c Wed Oct 22 21:39:00 2008 -0700 @@ -591,6 +591,8 @@ #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) +static bool vmap_initialized = false; + struct vmap_block_queue { spinlock_t lock; struct list_head free; @@ -827,6 +829,9 @@ int cpu; int flush = 0; + if (!vmap_initialized) + return; + for_each_possible_cpu(cpu) { struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu); struct vmap_block *vb; @@ -940,6 +945,8 @@ INIT_LIST_HEAD(&vbq->dirty); vbq->nr_dirty = 0; } + + vmap_initialized = true; } void unmap_kernel_range(unsigned long addr, unsigned long size) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org