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Mon, 03 Oct 2022 14:00:37 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH 1/3] mm/hugetlb: Fix race condition of uffd missing/minor handling From: Nadav Amit In-Reply-To: <20221003155630.469263-2-peterx@redhat.com> Date: Mon, 3 Oct 2022 14:00:36 -0700 Cc: LKML , Linux MM , Andrea Arcangeli , Mike Rapoport , David Hildenbrand , Andrew Morton , Axel Rasmussen , Mike Kravetz Content-Transfer-Encoding: quoted-printable Message-Id: References: <20221003155630.469263-1-peterx@redhat.com> <20221003155630.469263-2-peterx@redhat.com> To: Peter Xu X-Mailer: Apple Mail (2.3696.120.41.1.1) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664830839; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; 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dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3002AC0015 X-Rspam-User: X-Stat-Signature: zwebt4snc9judhpt46x5x6a54xmtuza7 X-HE-Tag: 1664830838-179124 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 Oct 3, 2022, at 8:56 AM, Peter Xu wrote: >=20 > + */ > + if (hugetlb_pte_stable(h, mm, ptep, old_pte)) > + ret =3D hugetlb_handle_userfault( > + vma, mapping, idx, flags, haddr, > + address, VM_UFFD_MISSING); > + else > + /* Retry the fault */ > + ret =3D 0; Might be unrelated, but at least for the sake of consistency if not potential GUP issues, don=E2=80=99t you want to return VM_FAULT_RETRY ?