Messages in this thread | | | From | Marc Dionne <> | Date | Fri, 10 Sep 2021 18:10:42 -0300 | Subject | Re: [PATCH 1/6] afs: Fix missing put on afs_read objects and missing get on the key therein |
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On Wed, Sep 8, 2021 at 12:58 PM David Howells <dhowells@redhat.com> wrote: > > The afs_read objects created by afs_req_issue_op() get leaked because > afs_alloc_read() returns a ref and then afs_fetch_data() gets its own ref > which is released when the operation completes, but the initial ref is > never released. > > Fix this by discarding the initial ref at the end of afs_req_issue_op(). > > This leak also covered another bug whereby a ref isn't got on the key > attached to the read record by afs_req_issue_op(). This isn't a problem as > long as the afs_read req never goes away... > > Fix this by calling key_get() in afs_req_issue_op(). > > This was found by the generic/074 test. It leaks a bunch of kmalloc-192 > objects each time it is run, which can be observed by watching > /proc/slabinfo. > > Fixes: f7605fa869cf ("afs: Fix leak of afs_read objects") > Reported-by: Marc Dionne <marc.dionne@auristor.com> > Signed-off-by: David Howells <dhowells@redhat.com> > cc: linux-afs@lists.infradead.org > Link: https://lore.kernel.org/r/163010394740.3035676.8516846193899793357.stgit@warthog.procyon.org.uk/ > --- > > fs/afs/file.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/afs/file.c b/fs/afs/file.c > index db035ae2a134..6688fff14b0b 100644 > --- a/fs/afs/file.c > +++ b/fs/afs/file.c > @@ -295,7 +295,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq) > fsreq->subreq = subreq; > fsreq->pos = subreq->start + subreq->transferred; > fsreq->len = subreq->len - subreq->transferred; > - fsreq->key = subreq->rreq->netfs_priv; > + fsreq->key = key_get(subreq->rreq->netfs_priv); > fsreq->vnode = vnode; > fsreq->iter = &fsreq->def_iter; > > @@ -304,6 +304,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq) > fsreq->pos, fsreq->len); > > afs_fetch_data(fsreq->vnode, fsreq); > + afs_put_read(fsreq); > } > > static int afs_symlink_readpage(struct page *page)
Tested that it prevents the leak of about 49K kmalloc-192 objects for a run of generic/074.
Reviewed-and-tested-by: Marc Dionne <marc.dionne@auristor.com>
Marc
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