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 9DAF210BA431 for ; Fri, 27 Mar 2026 07:12:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CBDFE6B00C6; Fri, 27 Mar 2026 03:12:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C95736B00C7; Fri, 27 Mar 2026 03:12:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD2746B00C8; Fri, 27 Mar 2026 03:12:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id AC1DE6B00C6 for ; Fri, 27 Mar 2026 03:12:41 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6B2298D5AA for ; Fri, 27 Mar 2026 07:12:41 +0000 (UTC) X-FDA: 84590975322.16.4CBCF51 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf27.hostedemail.com (Postfix) with ESMTP id E9DB74000A for ; Fri, 27 Mar 2026 07:12:39 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sp6tuO5d; spf=pass (imf27.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@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=1774595560; 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=U00RjldiyoskDcbDpqTQmzXBLsfo8bBiFLnezELd6kE=; b=5gkTaovY42ZuxTCrISVTZC48fgUl6Itt33ODiyeekkR2rTDxM+QhX7Q4+LoiU3luat6A6r GxvXkG34OQjkt7xICPls0fxrXsydqNGcF5jX4rLsaGTn7cmqIJVXBMFSym9RzT88uKAuSe bIVR/aOft3IUuTJxECBjKf5xsKl2OM0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774595560; a=rsa-sha256; cv=none; b=TsfNvx8aRw45aPzEJm0De/uhwR26Q4bnxGjAaZalgvYcOr4RnnU6FQ/mqIkzTSvaPa3orh gZ/miRtdlqb5yHccHxLG9ybJzH5fcA4xgwdkyHkB0psj1Geb7y6Hb2YRM0N8MUAeZbzHaV uBo7BPw5suQ5+JvG3CWDgg3o/UXnRV8= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sp6tuO5d; spf=pass (imf27.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 0FC5A41B26; Fri, 27 Mar 2026 07:12:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC1E2C19423; Fri, 27 Mar 2026 07:12:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774595558; bh=PItmMBxubPXbDaDdFWXsnbR+luD1aEAhbzGl7SFLZPc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sp6tuO5d9pGV1raZoHXRtGY96jXKIm4ROm5AlCmZXFn7QxpwFuNJUeFg5gTbc/TII 6PT2AR8Dpl0fFzcjkgh+RVmOBuO6IXUKbuoFf9MqUlnMgWx/Gmebdl973ejK4pWYgW Y4bMkQNxNBlQwnG4nVDKdjsYUDmbZjHSoeT/wXL/jHmmiSxaTFr44P9TS/lONeSPea 0ofvniHWmQ+y4X3P6pnbZawHQQPvNsBIwY1yJIfadGRiHTn/KED7vwXxMCk9pUSqBm PD+/iriMqKRAwyFQxBYj/LD7T01X3kL1e7CTVQnYPlIfEXm9laHcfaBlYpRC/HtywN Nhso0JpjQendQ== Date: Fri, 27 Mar 2026 10:12:28 +0300 From: Mike Rapoport To: James Houghton Cc: Andrew Morton , Andrea Arcangeli , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , "Liam R. Howlett" , Lorenzo Stoakes , "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 v2 08/15] shmem, userfaultfd: use a VMA callback to handle UFFDIO_CONTINUE Message-ID: References: <20260306171815.3160826-1-rppt@kernel.org> <20260306171815.3160826-9-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: E9DB74000A X-Stat-Signature: hx349e3r7g3sza7wpwhxd6hzqnoxorwp X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774595559-28112 X-HE-Meta: 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi James, On Thu, Mar 26, 2026 at 04:43:27PM -0700, James Houghton wrote: > On Fri, Mar 6, 2026 at 9:19 AM Mike Rapoport wrote: > > > > From: "Mike Rapoport (Microsoft)" > > > > When userspace resolves a page fault in a shmem VMA with UFFDIO_CONTINUE > > it needs to get a folio that already exists in the pagecache backing > > that VMA. > > > > Instead of using shmem_get_folio() for that, add a get_folio_noalloc() > > method to 'struct vm_uffd_ops' that will return a folio if it exists in > > the VMA's pagecache at given pgoff. > > > > Implement get_folio_noalloc() method for shmem and slightly refactor > > userfaultfd's mfill_get_vma() and mfill_atomic_pte_continue() to support > > this new API. > > > > Signed-off-by: Mike Rapoport (Microsoft) > > I found myself asking why HugeTLB wasn't included here; it's because > we call into hugetlb_mfill_atomic_pte() pretty early. It would be nice > to have HugeTLB implement get_folio_noalloc() and use the same path as > shmem, but we don't have to do that now. You are welcome to join the effort ;-) > Feel free to add: > > Reviewed-by: James Houghton Thanks! -- Sincerely yours, Mike.