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xen/balloon: don't alloc page while non-preemptible

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get_balloon_scratch_page() disables preemption so we cannot call
alloc_page() in between get/put_balloon_scratch_page().  Shuffle bits
around in decrease_reservation() to avoid this.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
David Vrabel 2013-09-19 17:14:53 +01:00 • committed by Konrad Rzeszutek Wilk
commit 24f69373e2
1 changed files with 11 additions and 12 deletions
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23
drivers/xen/balloon.c
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@ -398,8 +398,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
if (nr_pages > ARRAY_SIZE(frame_list)) if (nr_pages > ARRAY_SIZE(frame_list))
nr_pages = ARRAY_SIZE(frame_list); nr_pages = ARRAY_SIZE(frame_list);
scratch_page = get_balloon_scratch_page();
for (i = 0; i < nr_pages; i++) { for (i = 0; i < nr_pages; i++) {
page = alloc_page(gfp); page = alloc_page(gfp);
if (page == NULL) { if (page == NULL) {
@ -413,6 +411,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
scrub_page(page); scrub_page(page);
/*
* Ballooned out frames are effectively replaced with
* a scratch frame. Ensure direct mappings and the
* p2m are consistent.
*/
scratch_page = get_balloon_scratch_page();
#ifdef CONFIG_XEN_HAVE_PVMMU #ifdef CONFIG_XEN_HAVE_PVMMU
if (xen_pv_domain() && !PageHighMem(page)) { if (xen_pv_domain() && !PageHighMem(page)) {
ret = HYPERVISOR_update_va_mapping( ret = HYPERVISOR_update_va_mapping(
@ -422,24 +426,19 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
BUG_ON(ret); BUG_ON(ret);
} }
#endif #endif
}
/* Ensure that ballooned highmem pages don't have kmaps. */
kmap_flush_unused();
flush_tlb_all();
/* No more mappings: invalidate P2M and add to balloon. */
for (i = 0; i < nr_pages; i++) {
pfn = mfn_to_pfn(frame_list[i]);
if (!xen_feature(XENFEAT_auto_translated_physmap)) { if (!xen_feature(XENFEAT_auto_translated_physmap)) {
unsigned long p; unsigned long p;
p = page_to_pfn(scratch_page); p = page_to_pfn(scratch_page);
__set_phys_to_machine(pfn, pfn_to_mfn(p)); __set_phys_to_machine(pfn, pfn_to_mfn(p));
} }
put_balloon_scratch_page();
balloon_append(pfn_to_page(pfn)); balloon_append(pfn_to_page(pfn));
} }
put_balloon_scratch_page(); /* Ensure that ballooned highmem pages don't have kmaps. */
kmap_flush_unused();
flush_tlb_all();
set_xen_guest_handle(reservation.extent_start, frame_list); set_xen_guest_handle(reservation.extent_start, frame_list);
reservation.nr_extents = nr_pages; reservation.nr_extents = nr_pages;