diff options
| author | Xin Hao <xhao@linux.alibaba.com> | 2021-11-05 13:48:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-11-06 13:30:46 -0700 |
| commit | b5ca3e83ddb05342b1b30700b999cb9b107511f6 (patch) | |
| tree | ad0e7fc87f2bad35fcc949426c996975cc8e6dab /mm | |
| parent | a460a36034bad4403c2c62e04a521bc6987ae5db (diff) | |
| download | lwn-b5ca3e83ddb05342b1b30700b999cb9b107511f6.tar.gz lwn-b5ca3e83ddb05342b1b30700b999cb9b107511f6.zip | |
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>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/damon/core.c | 5 | ||||
| -rw-r--r-- | mm/damon/dbgfs.c | 15 |
2 files changed, 17 insertions, 3 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c index 6993c60ae31c..46a6afea3030 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -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); diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 6828e463348b..befb27a29aab 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -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; |