On Tue, 26 May 2020 09:56:58 +0200 SeongJae Park <[email protected]> wrote:
> From: SeongJae Park <[email protected]> > > This commit implements a debugfs interface for the data access > monitoring oriented memory management schemes. It is supposed to be > used by administrators and/or privileged user space programs. Users can > read and update the rules using ``<debugfs>/damon/schemes`` file. The > format is:: > > <min/max size> <min/max access frequency> <min/max age> <action> > > Signed-off-by: SeongJae Park <[email protected]> > --- > mm/damon.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 174 insertions(+), 2 deletions(-) > > diff --git a/mm/damon.c b/mm/damon.c > index 6a07649d1f5d..bcc732e8735c 100644 > --- a/mm/damon.c > +++ b/mm/damon.c > @@ -173,6 +173,29 @@ static void damon_destroy_task(struct damon_task *t) > damon_free_task(t); > } > + > +/* > + * Converts a string into an array of struct damos pointers > + * > + * Returns an array of struct damos pointers that converted if the conversion > + * success, or NULL otherwise. > + */ > +static struct damos **str_to_schemes(const char *str, ssize_t len, > + ssize_t *nr_schemes) > +{ > + struct damos *scheme, **schemes; > + const int max_nr_schemes = 256; > + int pos = 0, parsed, ret; > + unsigned int min_sz, max_sz, min_nr_a, max_nr_a, min_age, max_age; > + unsigned int action; > + > + schemes = kmalloc_array(max_nr_schemes, sizeof(scheme), > + GFP_KERNEL); > + if (!schemes) > + return NULL; > + > + *nr_schemes = 0; > + while (pos < len && *nr_schemes < max_nr_schemes) { > + ret = sscanf(&str[pos], "%u %u %u %u %u %u %u%n", > + &min_sz, &max_sz, &min_nr_a, &max_nr_a, > + &min_age, &max_age, &action, &parsed); > + if (ret != 7) > + break; > + if (action >= DAMOS_ACTION_LEN) { > + pr_err("wrong action %d\n", action); > + goto fail; > + } > + > + pos += parsed; > + scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a, > + min_age, max_age, action); > + if (!scheme) > + goto fail; > + > + schemes[*nr_schemes] = scheme; > + *nr_schemes += 1; > + } > + if (!*nr_schemes) > + goto fail; > + return schemes; > +fail: > + free_schemes_arr(schemes, *nr_schemes); > + return NULL; > +} > + > +static ssize_t debugfs_schemes_write(struct file *file, const char __user > *buf, > + size_t count, loff_t *ppos) > +{ > + struct damon_ctx *ctx = &damon_user_ctx; > + char *kbuf; > + struct damos **schemes; > + ssize_t nr_schemes = 0, ret; > + int err; > + > + if (*ppos) > + return -EINVAL; > + > + kbuf = kmalloc(count, GFP_KERNEL); > + if (!kbuf) > + return -ENOMEM; > + > + ret = simple_write_to_buffer(kbuf, count, ppos, buf, count); > + if (ret < 0) > + goto out; > + > + schemes = str_to_schemes(kbuf, ret, &nr_schemes); In case of wrong input, 'str_to_schemes()' could return NULL with non-zero nr_schemes, but the case is not handled here. I will properly handle the case in the next spin. Thanks, SeongJae Park > + > + mutex_lock(&ctx->kdamond_lock); > + if (ctx->kdamond) { > + ret = -EBUSY; > + goto unlock_out; > + } > + > + err = damon_set_schemes(ctx, schemes, nr_schemes); > + if (err) > + ret = err; > + else > + nr_schemes = 0; > +unlock_out: > + mutex_unlock(&ctx->kdamond_lock); > + free_schemes_arr(schemes, nr_schemes); > +out: > + kfree(kbuf); > + return ret; > +} > +
