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    Subject[12/17] 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.

    Signed-off-by: Christoph Lameter <clameter@sgi.com>

    ---
    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 2007-09-18 10:52:11.000000000 -0700
    +++ linux-2.6/mm/vmalloc.c 2007-09-18 10:54:21.000000000 -0700
    @@ -289,7 +289,6 @@ 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);

    @@ -314,7 +313,14 @@ 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)
    --
    -
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