On Mon, Sep 23, 2013 at 07:10:24PM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch changes transport_alloc_session_tags() to fall back to
> use vzalloc when kzalloc fails for big tag_num that end up generating
> larger order allocations.
Interesting.
How large can they be?
Does userspace control this?
If yes we definitely need to limit the memory this can
consume in some way ...
> Also use is_vmalloc_addr() in transport_alloc_session_tags() failure
> path, and normal transport_free_session() patch
which patch?
> to determine when
> vfree() needs to be called instead of kfree().
>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Asias He <asias@xxxxxxxxxx>
> Cc: Kent Overstreet <kmo@xxxxxxxxxxxxxx>
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_transport.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 4aace78..fd7a063 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -238,15 +238,21 @@ int transport_alloc_session_tags(struct se_session *se_sess,
>
> se_sess->sess_cmd_map = kzalloc(tag_num * tag_size, GFP_KERNEL);
This will spit warnings on failure, which you don't
want since it's expected here.
So add __GFP_NOWARN.
Also, vmalloc memory is slower, since this affects
data path, add __GFP_REPEAT too?
> if (!se_sess->sess_cmd_map) {
> - pr_err("Unable to allocate se_sess->sess_cmd_map\n");
> - return -ENOMEM;
> + se_sess->sess_cmd_map = vzalloc(tag_num * tag_size);
> + if (!se_sess->sess_cmd_map) {
> + pr_err("Unable to allocate se_sess->sess_cmd_map\n");
> + return -ENOMEM;
> + }
> }
>
> rc = percpu_ida_init(&se_sess->sess_tag_pool, tag_num);
> if (rc < 0) {
> pr_err("Unable to init se_sess->sess_tag_pool,"
> " tag_num: %u\n", tag_num);
> - kfree(se_sess->sess_cmd_map);
> + if (is_vmalloc_addr(se_sess->sess_cmd_map))
> + vfree(se_sess->sess_cmd_map);
> + else
> + kfree(se_sess->sess_cmd_map);
> se_sess->sess_cmd_map = NULL;
> return -ENOMEM;
> }
> @@ -412,7 +418,10 @@ void transport_free_session(struct se_session *se_sess)
> {
> if (se_sess->sess_cmd_map) {
> percpu_ida_destroy(&se_sess->sess_tag_pool);
> - kfree(se_sess->sess_cmd_map);
> + if (is_vmalloc_addr(se_sess->sess_cmd_map))
> + vfree(se_sess->sess_cmd_map);
> + else
> + kfree(se_sess->sess_cmd_map);
> }
> kmem_cache_free(se_sess_cache, se_sess);
> }
> --
> 1.7.10.4
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