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Tue, 01 Jun 2021 11:04:39 -0700 (PDT) MIME-Version: 1.0 References: <20210528005029.88088-1-almasrymina@google.com> <20210531162527.caeae9545ea2843c5f62bc9c@linux-foundation.org> <20210531173652.c21404a16a8f8542ce40afa8@linux-foundation.org> <83617ae4-90a1-24d0-a79c-4e259a928e04@oracle.com> In-Reply-To: <83617ae4-90a1-24d0-a79c-4e259a928e04@oracle.com> From: Mina Almasry Date: Tue, 1 Jun 2021 11:04:28 -0700 Message-ID: Subject: Re: [PATCH v4] mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY To: Mike Kravetz Cc: Andrew Morton , Axel Rasmussen , Peter Xu , Linux-MM , open list Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=QGbVsehE; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf19.hostedemail.com: domain of almasrymina@google.com designates 209.85.215.182 as permitted sender) smtp.mailfrom=almasrymina@google.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D140C9001E58 X-Stat-Signature: tfqnuep668g6dnm3scibjh6nn8n9688j X-HE-Tag: 1622570665-399674 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, Jun 1, 2021 at 10:09 AM Mike Kravetz wrote: > > On 5/31/21 7:48 PM, Mina Almasry wrote: > > On Mon, May 31, 2021 at 5:36 PM Andrew Morton wrote: > >> On Mon, 31 May 2021 17:11:52 -0700 Mina Almasry wrote: > >>> On Mon, May 31, 2021 at 4:25 PM Andrew Morton wrote: > >>>> On Thu, 27 May 2021 17:50:29 -0700 Mina Almasry wrote: > >>> I've sent 2 similar patches to the list: > >>> > >>> 1. "[PATCH v4] mm, hugetlb: Fix simple resv_huge_pages underflow on UFFDIO_COPY" > >>> > >>> This one is sent to -stable and linux-mm and is a fairly simple fix. > >>> > >>> 2. "[PATCH v4] mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY" > >> > >> Ah, OK, the title of the first patch was changed, which threw me off. > >> > >> I'd skipped "[PATCH v4] mm, hugetlb: Fix simple resv_huge_pages > >> underflow on UFFDIO_COPY" because Mike's comments appeared to require a > >> v5. I applied it and made Mike's changelog suggestions. Queued for > >> 5.13 and -stable. > >> > >> And I queued "[PATCH v4] mm, hugetlb: fix racy resv_huge_pages > >> underflow on UFFDIO_COPY" for 5.14. > >> > >> > > > > Awesome, thanks! And sorry for the confusion! > > > > Mina, does this patch depend on changes to restore_reserve_on_error()? > Yes, this patch (and only this patch) depends on your changes for complete and correct functionality. I'm not sure what's the impact > I am still working on those changes. It may be a few days before I can > have something finalized. > > If this does depend on restore_reserve_on_error as I suspect, perhaps we > should send these together. I was thinking it's fine to have my fix in Andrew's tree a few days before yours, since the race is hard to reproduce and even if the race reproduces the userfaultfd tests still pass, so I don't see any disastrous consequences, but I'm happy to do whatever is appropriate here. > -- > Mike Kravetz