Re: [PATCH v2] xen-netback: fix occasional leak of grant ref mappings under memory pressure

[David Miller]

From: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
Date: Thu, 28 Feb 2019 12:48:03 +0000

> Zero-copy callback flag is not yet set on frag list skb at the moment
> xenvif_handle_frag_list() returns -ENOMEM. This eventually results in
> leaking grant ref mappings since xenvif_zerocopy_callback() is never
> called for these fragments. Those eventually build up and cause Xen
> to kill Dom0 as the slots get reused for new mappings:
> 
> "d0v0 Attempt to implicitly unmap a granted PTE c010000329fce005"
> 
> That behavior is observed under certain workloads where sudden spikes
> of page cache writes coexist with active atomic skb allocations from
> network traffic. Additionally, rework the logic to deal with frag_list
> deallocation in a single place.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>

Applied and queued up for -stable, thanks.