On Wed, 20 Oct 2021 09:42:33 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote:
> When the ctx->adaptive_targets list is empty,
> I did some test on monitor_on interface like this.
>
> # echo > /sys/kernel/debug/damon/target_ids
Thanks for the change, but you missed writing 'on' to 'monitor_on' in the above
example.
>
> Though the ctx->adaptive_targets list is empty, but the
> kthread_run still be called, and the kdamond.x thread still
> be created, this is meaningless.
>
> So there adds a judgment in 'dbgfs_monitor_on_write',
> if the ctx->adaptive_targets list is empty, return -EINVAL.
>
> Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
Other parts looks good to me. However, seems this commit conflicts with a
patch[1] which already merged in -mm tree. Could you please rebase this on it?
FYI, all DAMON patches that merged in -mm tree are also applied on DAMON
development tree. So, you could get the patch applied tree by:
$ git remote add sj git://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git
$ git fetch sj
$ git checkout 0fa378d04b12
[1] https://lore.kernel.org/linux-mm/20211014073014.35754-1-sj@xxxxxxxxxx/
Thanks,
SJ
> ---
> include/linux/damon.h | 1 +
> mm/damon/core.c | 5 +++++
> mm/damon/dbgfs.c | 13 ++++++++++---
> 3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/damon.h b/include/linux/damon.h
> index 715dadd21f7c..4fce5f1f6dad 100644
> --- a/include/linux/damon.h
> +++ b/include/linux/damon.h
> @@ -316,6 +316,7 @@ void damon_destroy_scheme(struct damos *s);
>
> struct damon_target *damon_new_target(unsigned long id);
> void damon_add_target(struct damon_ctx *ctx, struct damon_target *t);
> +bool damon_targets_empty(struct damon_ctx *ctx);
> void damon_free_target(struct damon_target *t);
> void damon_destroy_target(struct damon_target *t);
> unsigned int damon_nr_regions(struct damon_target *t);
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 2f6785737902..c3a1374dbe0b 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -156,6 +156,11 @@ void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
> list_add_tail(&t->list, &ctx->adaptive_targets);
> }
>
> +bool damon_targets_empty(struct damon_ctx *ctx)
> +{
> + return list_empty(&ctx->adaptive_targets);
> +}
> +
> static void damon_del_target(struct damon_target *t)
> {
> list_del(&t->list);
> diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
> index 38188347d8ab..9dee29f7d103 100644
> --- a/mm/damon/dbgfs.c
> +++ b/mm/damon/dbgfs.c
> @@ -865,12 +865,19 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
> return -EINVAL;
> }
>
> - if (!strncmp(kbuf, "on", count))
> + if (!strncmp(kbuf, "on", count)) {
> + int i;
> +
> + for (i = 0; i < dbgfs_nr_ctxs; i++) {
> + if (damon_targets_empty(dbgfs_ctxs[i]))
> + return -EINVAL;
> + }
> err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
> - else if (!strncmp(kbuf, "off", count))
> + } else if (!strncmp(kbuf, "off", count)) {
> err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
> - else
> + } else {
> err = -EINVAL;
> + }
>
> if (err)
> ret = err;
> --
> 2.31.0
