Re: [PATCH AUTOSEL 4.19 100/237] libceph: don't consume a ref on pagelist in ceph_msg_data_add_pagelist()

[Sasha Levin]

On Sat, Nov 16, 2019 at 05:23:28PM +0100, Ilya Dryomov wrote:
> On Sat, Nov 16, 2019 at 4:43 PM Sasha Levin <sashal@xxxxxxxxxx> wrote:
> > From: Ilya Dryomov <idryomov@xxxxxxxxx>
> >
> > [ Upstream commit 894868330a1e038ea4a65dbb81741eef70ad71b1 ]
> >
> > Because send_mds_reconnect() wants to send a message with a pagelist
> > and pass the ownership to the messenger, ceph_msg_data_add_pagelist()
> > consumes a ref which is then put in ceph_msg_data_destroy().  This
> > makes managing pagelists in the OSD client (where they are wrapped in
> > ceph_osd_data) unnecessarily hard because the handoff only happens in
> > ceph_osdc_start_request() instead of when the pagelist is passed to
> > ceph_osd_data_pagelist_init().  I counted several memory leaks on
> > various error paths.
> >
> > Fix up ceph_msg_data_add_pagelist() and carry a pagelist ref in
> > ceph_osd_data.
> >
> > Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  fs/ceph/mds_client.c  | 2 +-
> >  net/ceph/messenger.c  | 1 +
> >  net/ceph/osd_client.c | 8 ++++++++
> >  3 files changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> > index 09db6d08614d2..94494d05a94cb 100644
> > --- a/fs/ceph/mds_client.c
> > +++ b/fs/ceph/mds_client.c
> > @@ -2184,7 +2184,6 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> >
> >         if (req->r_pagelist) {
> >                 struct ceph_pagelist *pagelist = req->r_pagelist;
> > -               refcount_inc(&pagelist->refcnt);
> >                 ceph_msg_data_add_pagelist(msg, pagelist);
> >                 msg->hdr.data_len = cpu_to_le32(pagelist->length);
> >         } else {
> > @@ -3289,6 +3288,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
> >         mutex_unlock(&mdsc->mutex);
> >
> >         up_read(&mdsc->snap_rwsem);
> > +       ceph_pagelist_release(pagelist);
> >         return;
> >
> >  fail:
> > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> > index f7d7f32ac673c..2c8cd339d59ea 100644
> > --- a/net/ceph/messenger.c
> > +++ b/net/ceph/messenger.c
> > @@ -3323,6 +3323,7 @@ void ceph_msg_data_add_pagelist(struct ceph_msg *msg,
> >
> >         data = ceph_msg_data_create(CEPH_MSG_DATA_PAGELIST);
> >         BUG_ON(!data);
> > +       refcount_inc(&pagelist->refcnt);
> >         data->pagelist = pagelist;
> >
> >         list_add_tail(&data->links, &msg->data);
> > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> > index 76c41a84550e7..c3494c1fb3a9a 100644
> > --- a/net/ceph/osd_client.c
> > +++ b/net/ceph/osd_client.c
> > @@ -126,6 +126,9 @@ static void ceph_osd_data_init(struct ceph_osd_data *osd_data)
> >         osd_data->type = CEPH_OSD_DATA_TYPE_NONE;
> >  }
> >
> > +/*
> > + * Consumes @pages if @own_pages is true.
> > + */
> >  static void ceph_osd_data_pages_init(struct ceph_osd_data *osd_data,
> >                         struct page **pages, u64 length, u32 alignment,
> >                         bool pages_from_pool, bool own_pages)
> > @@ -138,6 +141,9 @@ static void ceph_osd_data_pages_init(struct ceph_osd_data *osd_data,
> >         osd_data->own_pages = own_pages;
> >  }
> >
> > +/*
> > + * Consumes a ref on @pagelist.
> > + */
> >  static void ceph_osd_data_pagelist_init(struct ceph_osd_data *osd_data,
> >                         struct ceph_pagelist *pagelist)
> >  {
> > @@ -362,6 +368,8 @@ static void ceph_osd_data_release(struct ceph_osd_data *osd_data)
> >                 num_pages = calc_pages_for((u64)osd_data->alignment,
> >                                                 (u64)osd_data->length);
> >                 ceph_release_page_vector(osd_data->pages, num_pages);
> > +       } else if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGELIST) {
> > +               ceph_pagelist_release(osd_data->pagelist);
> >         }
> >         ceph_osd_data_init(osd_data);
> >  }
>
> Hi Sasha,
>
> This commit was part of a larger series and shouldn't be backported on
> its own.  Please drop it.

Dropped, thanks!

--
Thanks,
Sasha