[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 9/6/2013 11:09 AM, Stefano Stabellini wrote: You also might want to mention that this fixes the regression introduced by ..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> commit id <"title" 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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