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

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