From 64f9219d68f5c28af469bce8ec27cfaef07b9011 Mon Sep 17 00:00:00 2001 From: Andres Lagar-Cavilla Date: Thu, 16 Feb 2012 15:43:02 +0000 Subject: x86/mm: Fix more ballooning+paging and ballooning+sharing bugs If the guest balloons away a page that has been nominated for paging but not yet paged out, we fix: - Send EVICT_FAIL flag in the event to the pager - Do not leak the underlying page If the page was shared, we were not: - properly refreshing the mfn to balloon after the unshare. - unlocking the p2m on the error exit case Signed-off-by: Andres Lagar-Cavilla Acked-by: Tim Deegan Committed-by: Tim Deegan --- xen/arch/x86/mm/p2m.c | 7 +++++-- xen/common/memory.c | 17 ++++++++++++++++- 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index fd1ef34a73..19b831715e 100644 --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -929,11 +929,14 @@ void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn, req.gfn = gfn; req.flags = MEM_EVENT_FLAG_DROP_PAGE; - mem_event_put_request(d, &d->mem_event->paging, &req); - /* Update stats unless the page hasn't yet been evicted */ if ( p2mt != p2m_ram_paging_out ) atomic_dec(&d->paged_pages); + else + /* Evict will fail now, tag this request for pager */ + req.flags |= MEM_EVENT_FLAG_EVICT_FAIL; + + mem_event_put_request(d, &d->mem_event->paging, &req); } /** diff --git a/xen/common/memory.c b/xen/common/memory.c index 781053d00c..e0976b1f08 100644 --- a/xen/common/memory.c +++ b/xen/common/memory.c @@ -167,6 +167,15 @@ int guest_remove_page(struct domain *d, unsigned long gmfn) { guest_physmap_remove_page(d, gmfn, mfn, 0); put_gfn(d, gmfn); + /* If the page hasn't yet been paged out, there is an + * actual page that needs to be released. */ + if ( p2mt == p2m_ram_paging_out ) + { + ASSERT(mfn_valid(mfn)); + page = mfn_to_page(mfn); + if ( test_and_clear_bit(_PGC_allocated, &page->count_info) ) + put_page(page); + } p2m_mem_paging_drop_page(d, gmfn, p2mt); return 1; } @@ -181,7 +190,6 @@ int guest_remove_page(struct domain *d, unsigned long gmfn) return 0; } - page = mfn_to_page(mfn); #ifdef CONFIG_X86_64 if ( p2m_is_shared(p2mt) ) { @@ -190,10 +198,17 @@ int guest_remove_page(struct domain *d, unsigned long gmfn) * need to trigger proper cleanup. Once done, this is * like any other page. */ if ( mem_sharing_unshare_page(d, gmfn, 0) ) + { + put_gfn(d, gmfn); return 0; + } + /* Maybe the mfn changed */ + mfn = mfn_x(get_gfn_query_unlocked(d, gmfn, &p2mt)); + ASSERT(!p2m_is_shared(p2mt)); } #endif /* CONFIG_X86_64 */ + page = mfn_to_page(mfn); if ( unlikely(!get_page(page, d)) ) { put_gfn(d, gmfn); -- cgit v1.2.3