From: Jan Beulich Date: Thu, 17 Aug 2017 12:41:01 +0000 (+0200) Subject: gnttab: avoid spurious maptrack handle allocation failures X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~1668 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=d02f1a0b7576bafb2fba903c7e6e7221ab0d2847;p=xen.git gnttab: avoid spurious maptrack handle allocation failures When no memory is available in the hypervisor, rather than immediately failing the request, try to steal a handle from another vCPU. Reported-by: George Dunlap Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index a6926782b5..98de6664a1 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -430,7 +430,7 @@ get_maptrack_handle( struct vcpu *curr = current; unsigned int i, head; grant_handle_t handle; - struct grant_mapping *new_mt; + struct grant_mapping *new_mt = NULL; handle = __get_maptrack_handle(lgt, curr); if ( likely(handle != -1) ) @@ -439,10 +439,15 @@ get_maptrack_handle( spin_lock(&lgt->maptrack_lock); /* - * If we've run out of frames, try stealing an entry from another - * VCPU (in case the guest isn't mapping across its VCPUs evenly). + * If we've run out of handles and still have frame headroom, try + * allocating a new maptrack frame. If there is no headroom, or we're + * out of memory, try stealing an entry from another VCPU (in case the + * guest isn't mapping across its VCPUs evenly). */ - if ( nr_maptrack_frames(lgt) >= max_maptrack_frames ) + if ( nr_maptrack_frames(lgt) < max_maptrack_frames ) + new_mt = alloc_xenheap_page(); + + if ( !new_mt ) { spin_unlock(&lgt->maptrack_lock); @@ -465,12 +470,6 @@ get_maptrack_handle( return steal_maptrack_handle(lgt, curr); } - new_mt = alloc_xenheap_page(); - if ( !new_mt ) - { - spin_unlock(&lgt->maptrack_lock); - return -1; - } clear_page(new_mt); /*