Re: [RFC][PATCH] update /proc/sys/vm/drop_caches documentation

On Wed, 2010-09-15 at 13:53 +0900, KOSAKI Motohiro wrote:

quoted

quoted

 ==============================================================
 
diff -puN fs/drop_caches.c~update-drop_caches-documentation fs/drop_caches.c

--- linux-2.6.git/fs/drop_caches.c~update-drop_caches-documentation	2010-09-14 15:44:29.000000000 -0700
+++ linux-2.6.git-dave/fs/drop_caches.c	2010-09-14 15:58:31.000000000 -0700

@@ -47,6 +47,8 @@ int drop_caches_sysctl_handler(ctl_table
 {
 	proc_dointvec_minmax(table, write, buffer, length, ppos);
 	if (write) {
+		WARN_ONCE(1, "kernel caches forcefully dropped, "
+			     "see Documentation/sysctl/vm.txt\n");

Documentation updeta seems good but showing warning seems to be meddling to me.

Agreed.

If the motivation is blog's bogus rumor, this is no effective. I easily
imazine they will write "Hey, drop_caches may output strange message, 
but please ignore it!".

Fair enough.  But, is there a point that we _should_ be warning?  If
someone is doing this every minute, or every hour, something is pretty
broken.  Should we at least be doing a WARN_ON() so that the TAINT_WARN
is set?

I'm worried that there are users out there experiencing real problems
that aren't reporting it because "workarounds" like this just paper over
the issue.

-- Dave

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