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

Ilya Dryomov
2019-11-16T16:23:10Z

On Sat, Nov 16, 2019 at 4:43 PM Sasha Levin <sashal@kernel.org> wrote:
>
> From: Ilya Dryomov <idryomov@gmail.com>
>
> [ 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@gmail.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> 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.

Thanks,

Ilya