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mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on 

When the ctx->adaptive_targets list is empty, I did some test on
monitor_on interface like this.

    # cat /sys/kernel/debug/damon/target_ids
    #
    # echo on > /sys/kernel/debug/damon/monitor_on
    # damon: kdamond (5390) starts

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.

Link: https://lkml.kernel.org/r/0a60a6e8ec9d71989e0848a4dc3311996ca3b5d4.1634720326.git.xhao@linux.alibaba.com
Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xin Hao 2021-11-05 13:48:07 -07:00 committed by Linus Torvalds
parent a460a36034
commit b5ca3e83dd
3 changed files with 18 additions and 3 deletions
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1
include/linux/damon.h
View File

@ -440,6 +440,7 @@ 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);

5
mm/damon/core.c
View File

@ -180,6 +180,11 @@ 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);

15
mm/damon/dbgfs.c
View File

@ -878,12 +878,21 @@ 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])) {
kfree(kbuf);
return -EINVAL;
}
}
ret = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
else if (!strncmp(kbuf, "off", count))
} else if (!strncmp(kbuf, "off", count)) {
ret = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
else
} else {
ret = -EINVAL;
}
if (!ret)
ret = count;