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[74.12.30.48]) by smtp.gmail.com with ESMTPSA id t18-20020a05620a451200b006a6b374d8bbsm1797249qkp.69.2022.07.19.14.23.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jul 2022 14:23:35 -0700 (PDT) Date: Tue, 19 Jul 2022 17:23:33 -0400 From: Peter Xu To: Axel Rasmussen Cc: Alexander Viro , Andrew Morton , Dave Hansen , "Dmitry V . Levin" , Gleb Fotengauer-Malinovskiy , Hugh Dickins , Jan Kara , Jonathan Corbet , Mel Gorman , Mike Kravetz , Mike Rapoport , Nadav Amit , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , zhangyi , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 3/5] userfaultfd: selftests: modify selftest to use /dev/userfaultfd Message-ID: References: <20220719195628.3415852-1-axelrasmussen@google.com> <20220719195628.3415852-4-axelrasmussen@google.com> MIME-Version: 1.0 In-Reply-To: <20220719195628.3415852-4-axelrasmussen@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658265819; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=l1TU2R5pboSet6ITgX36x+voVt+WLRvd3J0ToQzPKr4=; b=03pGaZmvHIxBnVKR/dXWdzvX4Z3uX18fQScvwUpbKASb5AFqm78JZil7aQk5sqEndnVkTV 6E8OAtmXTrrXSReaQvI0uQZuAsOFCHdZXhJ7Wfugd2zH2zObL9lUUNG7IibeVpLS/I8avE xCa2KPjJD8bmjdt5y6uB/dPwLEM1eCU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658265819; a=rsa-sha256; cv=none; b=EfV2KOd8ZDm4nkfD91Ou0hZQ2MtANcH1FQv+3bU928mIzTr3yEcg1S8TmEwPUQ2G6kjjbQ uGk51c68LoLBf17Ak3IL57Q8dudJyAKswveiMzQvbexilicF3iQrDRz9Du1rX3lAryd3uh ukob4dTsFuYVLy3i4CGwyTwW6E2tY4c= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=DNOuLJki; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf29.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=peterx@redhat.com X-Rspamd-Queue-Id: 9093B120084 Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=DNOuLJki; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf29.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=peterx@redhat.com X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: 4t8f6j7tnm9hf7cs847p33wyrpbpmsn3 X-HE-Tag: 1658265818-151441 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jul 19, 2022 at 12:56:26PM -0700, Axel Rasmussen wrote: > We clearly want to ensure both userfaultfd(2) and /dev/userfaultfd keep > working into the future, so just run the test twice, using each > interface. > > Instead of always testing both userfaultfd(2) and /dev/userfaultfd, > let the user choose which to test. > > As with other test features, change the behavior based on a new > command line flag. Introduce the idea of "test mods", which are > generic (not specific to a test type) modifications to the behavior of > the test. This is sort of borrowed from this RFC patch series [1], but > simplified a bit. > > The benefit is, in "typical" configurations this test is somewhat slow > (say, 30sec or something). Testing both clearly doubles it, so it may > not always be desirable, as users are likely to use one or the other, > but never both, in the "real world". > > [1]: https://patchwork.kernel.org/project/linux-mm/patch/20201129004548.1619714-14-namit@vmware.com/ > > Signed-off-by: Axel Rasmussen Acked-by: Peter Xu -- Peter Xu