Messages in this thread Patch in this message | | | Date | Thu, 23 Oct 2008 16:48:17 -0700 | From | Jeremy Fitzhardinge <> | Subject | vm_unmap_aliases and Xen |
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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 <jeremy.fitzhardinge@citrix.com> 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)
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