From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C73AFF60D8 for ; Tue, 31 Mar 2026 07:50:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 92F646B008C; Tue, 31 Mar 2026 03:50:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8DF236B0095; Tue, 31 Mar 2026 03:50:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7CDFC6B0096; Tue, 31 Mar 2026 03:50:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 67D8F6B008C for ; Tue, 31 Mar 2026 03:50:57 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 1D55A13C0FB for ; Tue, 31 Mar 2026 07:50:57 +0000 (UTC) X-FDA: 84605586954.30.D98362F Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf15.hostedemail.com (Postfix) with ESMTP id 7CE15A000F for ; Tue, 31 Mar 2026 07:50:55 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=otLloVur; spf=pass (imf15.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774943455; 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=2/eAR0lsoXbDXd70Lr9orNLGdpQBp5tCLrYPE0/B3RI=; b=Cb18Y2BbfXb3+nkKum6O9EU8qtFe+/jN8faFzSlclZ/W0a176H26r6VJvpPTtYV4yr/S16 jGV0BrapRg+To1lBTEBM4IUx0uLt6oX/Su5XRiL1r/PG+j3sd2wP0UvGInFNmM/HdKw2sh guJjX5YlziMqW2H2kkg8wpH5Pcy6BVM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774943455; a=rsa-sha256; cv=none; b=GFop1cdXTrJrtHcH7mLooeMjigmlZ3fRFI8QauIBM7RrO9DaNDjnK6w2lD42G7m4ffjFM7 j8/0W43ZYvuipc4b6U0O76Hh+Flf9J6vmn5KyWyaEfsczymqGSJrTXmuhdq9jVbXtO5KKc 9wQ1jNVOUy54WPzvijElTEr6dRSL7+c= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=otLloVur; spf=pass (imf15.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CECDA600CB; Tue, 31 Mar 2026 07:50:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26696C19423; Tue, 31 Mar 2026 07:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774943454; bh=QmBrY5BKVbXz9CXTgV6unLVzlvXFNRWXO9R3+/R7gS0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=otLloVurIebAAh64mVkWyy1Yx4OPNvjHY6Wavo2/t4scZtIey5FAsclGVAReyXELv acxPd9t/ZfkfPv+8RIRukk+mhkmlBvA+a2FBtpVBpcMXMdKf9jax1Ic5HrqbXCTaup L75gDcEL/qZJCWDPtiE0uv2tcJ6ipRACww0DE+70ADtXMBfVxH1qiK2c2+ILM1nif2 c6tAhrmqudLZPc4H8kWeC1d15Fd6KPnMbP8ucuuzdJcntZ/ZyBTViRoOtw++xYFqIP mZ8dgFOzD3fLbeFA3spBT4TBU6/1zqW4GUaEm90ycw/3i2nT+5rj39NOfszj0isSvg 0qPx21ePK4h+w== Date: Tue, 31 Mar 2026 16:50:52 +0900 From: "Harry Yoo (Oracle)" To: Mike Rapoport Cc: Andrew Morton , Andrea Arcangeli , Andrei Vagin , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , "Lorenzo Stoakes (Oracle)" , "Matthew Wilcox (Oracle)" , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 03/15] userfaultfd: introduce mfill_establish_pmd() helper Message-ID: References: <20260330101116.1117699-1-rppt@kernel.org> <20260330101116.1117699-4-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260330101116.1117699-4-rppt@kernel.org> X-Rspamd-Queue-Id: 7CE15A000F X-Stat-Signature: wqpdrpz3eysnq35r7ofbuheax8c1hy3p X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774943455-452075 X-HE-Meta: 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 FA5GAaDU 5udIWj6bpV3uOMrTeUdaubKniHydhIxo2Uxn8+ereVQKrNAVW4ZuRYtTap7bb4DQNAs6GOSotNp6Ofs/pKV3SA2Ty97drbvSzLazj2lZR3HqOtFBTYm90tqD8dzkKCVc26AVoB5xVjHiKv6VKxHvKzzSt4Zapo75CI0YmHwIrG5L6Q3DSxGNJcfv7QizKEfKdU5Ug9v52rVrRMiPtBJcLajJi3v2QC6RUCiajPTSnrMN0LHnSdF0bvcbmEea8vekORhn9Tw98Z2kuvnwBOLOWxBwCYQ4CWkPZG0aM2u/frSVmy2ng5nWLc221DM9dXg9S2Tj9 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 30, 2026 at 01:11:04PM +0300, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > There is a lengthy code chunk in mfill_atomic() that establishes the PMD > for UFFDIO operations. This code may be called twice: first time when the > copy is performed with VMA/mm locks held and the other time after the copy > is retried with locks dropped. > > Move the code that establishes a PMD into a helper function so it can be > reused later during refactoring of mfill_atomic_pte_copy(). > > Signed-off-by: Mike Rapoport (Microsoft) > --- Looks good to me, Acked-by: Harry Yoo (Oracle) > mm/userfaultfd.c | 102 ++++++++++++++++++++++++----------------------- > 1 file changed, 52 insertions(+), 50 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index fa9622ec7279..291e5cfed431 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > +static int mfill_establish_pmd(struct mfill_state *state) > +{ > + struct mm_struct *dst_mm = state->ctx->mm; > + pmd_t *dst_pmd, dst_pmdval; > + > + dst_pmd = mm_alloc_pmd(dst_mm, state->dst_addr); > + if (unlikely(!dst_pmd)) > + return -ENOMEM; > + > + dst_pmdval = pmdp_get_lockless(dst_pmd); > + if (unlikely(pmd_none(dst_pmdval)) && > + unlikely(__pte_alloc(dst_mm, dst_pmd))) > + return -ENOMEM; > + > + dst_pmdval = pmdp_get_lockless(dst_pmd); > + /* > + * If the dst_pmd is THP don't override it and just be strict. > + * (This includes the case where the PMD used to be THP and > + * changed back to none after __pte_alloc().) > + */ > + if (unlikely(!pmd_present(dst_pmdval) || pmd_leaf(dst_pmdval))) Just noting: ^ this was pmd_trans_huge() but now it is pmd_leaf(). but since the present bit is separately checked and hugetlb vma is handled in a different path I don't expect functional change. > + return -EEXIST; > + if (unlikely(pmd_bad(dst_pmdval))) > + return -EFAULT; > + > + state->pmd = dst_pmd; > + return 0; > +} -- Cheers, Harry / Hyeonggon