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[XFS] eagerly remove vmap mappings to avoid upsetting Xen 

XFS leaves stray mappings around when it vmaps memory to make it virtually
contigious. This upsets Xen if one of those pages is being recycled into a
pagetable, since it finds an extra writable mapping of the page.

This patch solves the problem in a brute force way, by making XFS always
eagerly unmap its mappings.

SGI-PV: 971902
SGI-Modid: xfs-linux-melb:xfs-kern:29886a

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
This commit is contained in:
Jeremy Fitzhardinge 2007-10-17 13:55:03 +10:00 committed by Tim Shimmin
parent 6572bc28de
commit 7f01507234
1 changed files with 13 additions and 0 deletions
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13
fs/xfs/linux-2.6/xfs_buf.c
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@ -187,6 +187,19 @@ free_address(
{
a_list_t *aentry;
#ifdef CONFIG_XEN
/*
* Xen needs to be able to make sure it can get an exclusive
* RO mapping of pages it wants to turn into a pagetable. If
* a newly allocated page is also still being vmap()ed by xfs,
* it will cause pagetable construction to fail. This is a
* quick workaround to always eagerly unmap pages so that Xen
* is happy.
*/
vunmap(addr);
return;
#endif
aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT);
if (likely(aentry)) {
spin_lock(&as_lock);