Hi Randy, On Thu, 9 Feb 2023 19:26:43 -0800 Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > Hi, > > On 2/9/23 11:20, SeongJae Park wrote: > > DAMON debugfs interface has announced to be deprecated after >v5.15 LTS > > kernel is released. And, v6.1.y has announced to be an LTS[1]. > > > > Though the announcement was there for a while, some people might not > > noticed that so far. Also, some users could depend on it and have > > problems at movng to the alternative (DAMON sysfs interface). > > > > For such cases, warn DAMON debugfs interface deprecation with contacts > > to ask helps when any DAMON debugfs interface file is opened. > > > > [1] https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=332e9121320bc7461b2d3a79665caf153e51732c > > > > Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> > > --- > > mm/damon/dbgfs.c | 16 ++++++++++++++++ > > 1 file changed, 16 insertions(+) > > > > diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c > > index b3f454a5c682..e551a20b35e3 100644 > > --- a/mm/damon/dbgfs.c > > +++ b/mm/damon/dbgfs.c > > @@ -20,6 +20,11 @@ static int dbgfs_nr_ctxs; > > static struct dentry **dbgfs_dirs; > > static DEFINE_MUTEX(damon_dbgfs_lock); > > > > +static void damon_dbgfs_warn_deprecation(void) > > +{ > > + pr_warn_once("DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS). If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); > > +} > > Line length of 234 is a bit over the limit. > I think it would be OK to split it at the end of the first sentence, like: > > pr_warn_once("DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS).\n"); > pr_warn_once("If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); > > or would that [2 pr_warn_once() calls] not work for some reason? > > Or even: > > pr_warn_once( > "DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS).\n"); > pr_warn_once( > "If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); > > although some people might gag at that one. Thank you for your opinion. I considered that, but I was worrying if some other messages come between those two separated messages. What do you think about breaking the string like below? I first tried to do so like memcg hierarchy[1], but ended up to this version because of checkpatch.pl outputs[2]. However, if others doesn't care, I think this is ok. pr_warn_once("DAMON debugfs interface is deprecated, " "so users should move DAMON_SYSFS. If you depend on this " "and cannot move, please report your usecase to " "damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); If breaking user-visible string is not ok, maybe we could make it as short as your above example. pr_warn_once("DAMON_DBGFS is deprecated; please contact to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx if you depend on it.\n"); May I ask your opinion? [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memcontrol.c?h=v6.1#n3643 [2] https://docs.kernel.org/process/coding-style.html#breaking-long-lines-and-strings Thanks, SJ > > > -- > ~Randy
