From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, patches@lists.linux.dev,
tglx@linutronix.de, linux-crypto@vger.kernel.org,
linux-api@vger.kernel.org, x86@kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
Carlos O'Donell <carlos@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Jann Horn <jannh@google.com>,
Christian Brauner <brauner@kernel.org>,
David Hildenbrand <dhildenb@redhat.com>,
linux-mm@kvack.org
Subject: Re: [PATCH v19 1/5] mm: add VM_DROPPABLE for designating always lazily freeable mappings
Date: Tue, 2 Jul 2024 17:08:34 +0200 [thread overview]
Message-ID: <ZoQX8uxqww6Zkq2C@zx2c4.com> (raw)
In-Reply-To: <20240702004254.3ab2db4a98cb7fdd245407cb@linux-foundation.org>
Hey Andrew,
On Tue, Jul 02, 2024 at 12:42:54AM -0700, Andrew Morton wrote:
> The patch is impressively comment-free. It is a little harsh to make
> readers go poking around in the git history to figure out what
> VM_DROPPABLE is, and why it exists.
Sure, I'll add some comments to the conditionals added to make it more
clear.
> Seems hard to test that this mode is working correctly. Can you think
> of a way for userspace to check this? And if so, add it to selftests?
I've got a pretty straight forward test I've been using during my own
testing that I can add to the vgetrandom_alloc() selftest (which exposes
these code paths). It works fairly reliably. Basically, one process
keeps checking to see if the memory has been dropped, while the other
consumes memory a page at a time. Pretty soon (depending on how much ram
you have), the memory gets dropped, and this is detected, and the test
completes with a pass. I'll have this in v+1 of this series.
Jason
prev parent reply other threads:[~2024-07-02 15:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240701135801.3698-1-Jason@zx2c4.com>
2024-07-01 13:57 ` Jason A. Donenfeld
2024-07-02 7:42 ` Andrew Morton
2024-07-02 15:08 ` Jason A. Donenfeld [this message]
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