Hi Anna,
On Wed, 2019-02-13 at 16:53 -0500, Trond Myklebust wrote:
> When we fail to add the request to the I/O queue, we currently leave
> it
> to the caller to free the failed request. However since some of the
> requests that fail are actually created by nfs_pageio_add_request()
> itself, and are not passed back the caller, this leads to a leakage
> issue, which can again cause page locks to leak.
>
> This commit addresses the leakage by freeing the created requests on
> error, using desc->pg_completion_ops->error_cleanup()
>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Fixes: a7d42ddb30997 ("nfs: add mirroring support to pgio layer")
> Cc: stable@xxxxxxxxxxxxxxx # v4.0+
I believe this patch should fix the page lock leak that I mentioned
yesterday. The issue is that we're creating nfs_page structures as part
of a page group, but then abandoning those structures to their fate. It
means that the calls to nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE),
nfs_page_group_sync_on_bit(req, PG_WB_END), and even
nfs_page_group_sync_on_bit(req, PG_TEARDOWN) can never succeed, and so
we end up leaking, page locks, page writeback locks, and nfs_page
requests...
Cheers
Trond
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
