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From: Peter Xu <peterx@redhat.com>
To: Axel Rasmussen <axelrasmussen@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Brian Geffon <bgeffon@google.com>,
	Christian Brauner <brauner@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Gaosheng Cui <cuigaosheng1@huawei.com>,
	Huang Ying <ying.huang@intel.com>,
	Hugh Dickins <hughd@google.com>,
	James Houghton <jthoughton@google.com>,
	"Jan Alexander Steffens (heftig)" <heftig@archlinux.org>,
	Jiaqi Yan <jiaqiyan@google.com>, Jonathan Corbet <corbet@lwn.net>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	"Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	"Mike Rapoport (IBM)" <rppt@kernel.org>,
	Muchun Song <muchun.song@linux.dev>,
	Nadav Amit <namit@vmware.com>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	Ryan Roberts <ryan.roberts@arm.com>,
	Shuah Khan <shuah@kernel.org>,
	Suleiman Souhlal <suleiman@google.com>,
	Suren Baghdasaryan <surenb@google.com>,
	"T.J. Alumbaugh" <talumbau@google.com>,
	Yu Zhao <yuzhao@google.com>, ZhangPeng <zhangpeng362@huawei.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 7/8] selftests/mm: refactor uffd_poll_thread to allow custom fault handlers
Date: Fri, 7 Jul 2023 17:00:49 -0400	[thread overview]
Message-ID: <ZKh9AT96XiZ+6nCC@x1n> (raw)
In-Reply-To: <CAJHvVci6qCv+d7Hz0QkqeuEZze0OFJt0P9qnWgA_cgDeaLmptQ@mail.gmail.com>

On Fri, Jul 07, 2023 at 01:38:16PM -0700, Axel Rasmussen wrote:
> Ah, so I tried switching back to the {0} initializer, and was reminded
> why I didn't do that in v1. :) Ignoring the missing braces warning I
> talked about before, using {0} here is actually an error
> ("variable-sized object may not be initialized") because this is a
> variable sized array (nr_cpus isn't constant). So, that option is out.
> 
> I'm not a huge fan of adding the free() cleanup and dealing with all
> of the err() calls this function has.

Oh, that's definitely not needed - as long as we know we're going to quit,
we let kernel clean everything is fine.

I just worry in the future there can be a loop of userfaultfd_stress() so
it can OOM a host even if no err() hit but by looping.  I hope I explained
what I meant.. so it's still good we make sure things freed properly when
in success paths and when we're at it.

> 
> Originally I switched to calloc() because I'm not a big fan of VLAs
> anyway. But, as a compromise in v4 I'll leave it a VLA, and switch to
> memset() for initializing it.

That'll be good enough to me.  Thanks a lot,

-- 
Peter Xu


  reply	other threads:[~2023-07-07 21:01 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-06 22:50 [PATCH v3 0/8] add UFFDIO_POISON to simulate memory poisoning with UFFD Axel Rasmussen
2023-07-06 22:50 ` [PATCH v3 1/8] mm: make PTE_MARKER_SWAPIN_ERROR more general Axel Rasmussen
2023-07-07 13:10   ` Peter Xu
2023-07-06 22:50 ` [PATCH v3 2/8] mm: userfaultfd: check for start + len overflow in validate_range Axel Rasmussen
2023-07-07 13:14   ` Peter Xu
2023-07-06 22:50 ` [PATCH v3 3/8] mm: userfaultfd: extract file size check out into a helper Axel Rasmussen
2023-07-07 13:15   ` Peter Xu
2023-07-06 22:50 ` [PATCH v3 4/8] mm: userfaultfd: add new UFFDIO_POISON ioctl Axel Rasmussen
2023-07-07 13:37   ` Peter Xu
2023-07-07 19:56     ` Axel Rasmussen
2023-07-06 22:50 ` [PATCH v3 5/8] mm: userfaultfd: support UFFDIO_POISON for hugetlbfs Axel Rasmussen
2023-07-07 13:39   ` Peter Xu
2023-07-06 22:50 ` [PATCH v3 6/8] mm: userfaultfd: document and enable new UFFDIO_POISON feature Axel Rasmussen
2023-07-06 22:50 ` [PATCH v3 7/8] selftests/mm: refactor uffd_poll_thread to allow custom fault handlers Axel Rasmussen
2023-07-07 13:42   ` Peter Xu
2023-07-07 17:03     ` Axel Rasmussen
2023-07-07 20:38       ` Axel Rasmussen
2023-07-07 21:00         ` Peter Xu [this message]
2023-07-06 22:50 ` [PATCH v3 8/8] selftests/mm: add uffd unit test for UFFDIO_POISON Axel Rasmussen

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