Re: [PATCH 4.19 071/114] kernel: sysctl: make drop_caches write-only

Pavel Machek
2020-01-03T18:29:18Z

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Hi!

> From: Johannes Weiner <hannes@cmpxchg.org>
>
> [ Upstream commit 204cb79ad42f015312a5bbd7012d09c93d9b46fb ]
>
> Currently, the drop_caches proc file and sysctl read back the last value
> written, suggesting this is somehow a stateful setting instead of a
> one-time command. Make it write-only, like e.g. compact_memory.

I have no problem with that, but is it good idea for stable?

Plus, I seem to recall that drop_caches was somehow dangerous,
debugging-only stuff, one should not use on production system. Did
that get fixed in the meantime?

Best regards,
Pavel

> @@ -1411,7 +1411,7 @@ static struct ctl_table vm_table[] = {
> .procname = "drop_caches",
> .data = &sysctl_drop_caches,
> .maxlen = sizeof(int),
> - .mode = 0644,
> + .mode = 0200,
> .proc_handler = drop_caches_sysctl_handler,
> .extra1 = &one,
> .extra2 = &four,

--
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