[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/p2m: Don't call get_balloon_scratch_page() twice, keep interrupts disabled for multicalls
On Fri, 6 Sep 2013, Boris Ostrovsky wrote: > m2p_remove_override() calls get_balloon_scratch_page() in > MULTI_update_va_mapping() even though it already has pointer to this page from > the earlier call (in scratch_page). This second call doesn't have a matching > put_balloon_scratch_page() thus not restoring preempt count back. (Also, there > is no put_balloon_scratch_page() in the error path.) > > In addition, the second multicall uses __xen_mc_entry() which does not disable > interrupts. Rearrange xen_mc_* calls to keep interrupts off while performing > multicalls. > > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > arch/x86/xen/p2m.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > index 0d4ec35..8b901e8 100644 > --- a/arch/x86/xen/p2m.c > +++ b/arch/x86/xen/p2m.c > @@ -990,10 +990,13 @@ int m2p_remove_override(struct page *page, > printk(KERN_WARNING "m2p_remove_override: " > "pfn %lx mfn %lx, failed to > modify kernel mappings", > pfn, mfn); > + put_balloon_scratch_page(); > return -1; > } > > - mcs = xen_mc_entry( > + xen_mc_batch(); > + > + mcs = __xen_mc_entry( > sizeof(struct > gnttab_unmap_and_replace)); > unmap_op = mcs.args; > unmap_op->host_addr = kmap_op->host_addr; > @@ -1003,12 +1006,11 @@ int m2p_remove_override(struct page *page, > MULTI_grant_table_op(mcs.mc, > GNTTABOP_unmap_and_replace, unmap_op, > 1); > > - xen_mc_issue(PARAVIRT_LAZY_MMU); > - > mcs = __xen_mc_entry(0); > MULTI_update_va_mapping(mcs.mc, scratch_page_address, > - > pfn_pte(page_to_pfn(get_balloon_scratch_page()), > + pfn_pte(page_to_pfn(scratch_page), > PAGE_KERNEL_RO), 0); > + > xen_mc_issue(PARAVIRT_LAZY_MMU); > > kmap_op->host_addr = 0; > -- > 1.8.3.1 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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