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[70.31.27.79]) by smtp.gmail.com with ESMTPSA id e9-20020ac86709000000b0035d44917542sm10363073qtp.37.2022.10.03.14.16.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 14:16:58 -0700 (PDT) Date: Mon, 3 Oct 2022 17:16:55 -0400 From: Peter Xu To: Nadav Amit Cc: LKML , Linux MM , Andrea Arcangeli , Mike Rapoport , David Hildenbrand , Andrew Morton , Axel Rasmussen , Mike Kravetz Subject: Re: [PATCH 1/3] mm/hugetlb: Fix race condition of uffd missing/minor handling Message-ID: References: <20221003155630.469263-1-peterx@redhat.com> <20221003155630.469263-2-peterx@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664831822; a=rsa-sha256; cv=none; b=itCqjkmrnHu+YyxcajjLPA3OKp/JUDTNKUxpHNOfja0vs2ph5WB65N62YHBitHVRP+hVEl EOKIZ5bJPqAcZz9sVG5Q2gvGxOJThX8yzS0HowFeWeTYC7ggPYyjdAlrKHFS62GYv9rw7t YX/X4mGQZIWho7/WYErGw96plJaWHDk= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=bM+jm6Qe; spf=pass (imf04.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664831822; 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; bh=yDq2aLp/FgG9bJgxiiUy2Vo1uVdxseE75P7hxe9A1A0=; b=toG8rUlqqp5hDwHP9WgvLGL1/UO5S1eK6OSVpNd+qhgTlIqGTt38ZGbPbKRkth1MJk1aqJ dsQlTJ+4JJC9j6n/yKNi+Bh2YAq4mvOBA4DMuUfPP3WMy6rxLqGSVb+W8VrOUHTgULfO/p 9y4sI8Yo7Odv4XBKahqD+/TMUZSlgxw= X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C27504001B X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=bM+jm6Qe; spf=pass (imf04.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Stat-Signature: n3sjgxjau375hcs5o6x13kjssjxi9xqe X-HE-Tag: 1664831821-379376 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 Mon, Oct 03, 2022 at 02:00:36PM -0700, Nadav Amit wrote: > On Oct 3, 2022, at 8:56 AM, Peter Xu wrote: > > > > > + */ > > + if (hugetlb_pte_stable(h, mm, ptep, old_pte)) > > + ret = hugetlb_handle_userfault( > > + vma, mapping, idx, flags, haddr, > > + address, VM_UFFD_MISSING); > > + else > > + /* Retry the fault */ > > + ret = 0; > > Might be unrelated, but at least for the sake of consistency if not > potential GUP issues, don’t you want to return VM_FAULT_RETRY ? VM_FAULT_RETRY implies releasing of mmap sem, while we didn't? -- Peter Xu