From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E17D8606A321 for ; Tue, 27 Oct 2026 08:18:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lrkj80Hq Received: by kanga.kvack.org (Postfix) id EAA7D6B0615; Tue, 27 Oct 2026 04:18:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E81FB6B0617; Tue, 27 Oct 2026 04:18:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D710E6B0618; Tue, 27 Oct 2026 04:18:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B8BD86B0615 for ; Tue, 27 Oct 2026 04:18:06 -0400 (EDT) Received: from smtpin23.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3BD84A8364 for ; Tue, 27 Oct 2026 08:18:06 +0000 (UTC) X-FDA: 85367703372.23.2381747 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf12.hostedemail.com (Postfix) with ESMTP id ACD9D40007 for ; Tue, 27 Oct 2026 08:18:04 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=lrkj80Hq; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf12.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793089084; 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=D64FFgpc7INZHjHGIMuz6fOYnjN+R/6alnjku+MmCwI=; b=2vMwvTRz6C7FzI1Lqaq+9TeH+/i16TxyrTpSeDRo/lNzuuPp9CkVCol/ZudrgIUkXfVcar xAdoBCR3FMGHcD/z8JX7b7WMbMPGJRbkVC2oeJP6M03itB9JXIFuBR1bJm0fBELIW57QaZ aHqT4ayfjNGmdmmJ7W/cw5nry22SntI= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=lrkj80Hq; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf12.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793089084; b=g0OhKSllPMjKTyIIIS9BSENNgfHYlDpJJqpdk9CAdezI/qqQHLJ3huvhorf8aYVmYzhPER i6BM56A2bSAlYBBKkBOUOTl18FDyJ/F0b+o33vNaYZ954C8cEbKJbnqol85Q6rZlaefeud 3xCAvRcg/y5MTg1bHjKAff/DZTcamN4= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 3B349601F0; Tue, 27 Oct 2026 08:18:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8565F1F01825; Tue, 27 Oct 2026 08:17:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793089083; bh=D64FFgpc7INZHjHGIMuz6fOYnjN+R/6alnjku+MmCwI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=lrkj80HqsRK7SmEUA0UlfQ9awwfrnZbTGOTFJ38sN0K5sYRFKCiWceFy/zEcA5N7K X/+Ja8dZnecwCLwqQW2Q53xYQZvfTTZvXc/UlZpQ3ww44q5sovpt7pTsmVFSsALwmW con0FeRikx0qegOPeuI08/JqIvHO7h8RUPar2Oksdd8psB92RcYHO67CJO4Oifo4bl 4OdMIpYuvOM127oapLRHduPwvwZb4shBXArXcUwWQ3OGDl6t28H8bKbs77c3ilGNzD RxpfugSOkHtwZ9bqmFJhB2XCngY1YfFKNWjupoESw2HcBJREXTXw0o5pJ9DqJ4U+FM VgHlaWwITa29Q== Date: Tue, 27 Oct 2026 10:17:41 +0200 From: Mike Rapoport To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org Subject: Re: [PATCH 24/46] mm/userfaultfd: wake all waiters on unregister Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-24-6f74bec9a5bb@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-24-6f74bec9a5bb@kernel.org> X-Rspamd-Queue-Id: ACD9D40007 X-Rspam-User: X-Stat-Signature: ic3zxo8xu5n59w1b4k6tqu3ctxrkzrkd X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam03 X-HE-Tag: 1793089084-316801 X-HE-Meta: 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 A3P9/y4Z 4/alaOhSZ8qMm3u4bhNSL5kKFMihTRd11YM7LmldgOS5Bs6h0egp2qenOtpabvXt9K5fO0hVGTXLyNzrNlLHtdwcRTV05cOBMWpYux1VlnAbBhu19y0x66ahZlCAxJOhEYDfSp+MxmC9mWaniZpOEolMIqo2wY2lPpjsSOrq5IfhbCLLHVQLDNxFNGSSkHFBto+y/VXiYZCxoeDw8Kx1Sr1B4vMKx1EfkmjSSVTOqaaE5fyqgdgCrr99QGQeIg2c3DriFUYa4/our2oE9QfIA2Fwdk7fENgDIobbqCZPplt//ISZburios+DXlaJox3jZvYzlqWC6Q7luHmYhpqkNm12FLgKj9NjSZEX0OBET6tX3X9xSwxxv0rA/HDu/UoscpP5un4SQ7LOW7GSu8KEA56zr7hxj3oai6PJx Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 27, 2026 at 12:17:44AM +0100, David Hildenbrand (Arm) wrote: > From: Josef Bacik > > UFFDIO_UNREGISTER only wakes pending faults if VM_UFFD_MISSING is set. > Threads waiting on write-protect, minor or RWP faults can therefore remain > asleep after unregistering a range that does not track missing faults. > > Wake pending faults regardless of the registration mode so they can retry > without an explicit UFFDIO_WAKE or closing the userfaultfd. This matches > the existing behavior for missing faults, including removing unread fault > messages for the woken waiters. > > Fix generated by an LLM and sent by Josef Bacik in private. > > Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") > Cc: stable@vger.kernel.org > Signed-off-by: Josef Bacik > [ david: rebase; simplify description ] > Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Mike Rapoport (Microsoft) > --- > mm/userfaultfd.c | 22 ++++++++++------------ > 1 file changed, 10 insertions(+), 12 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 7e30b5ff17be1..2122676c4220f 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -3977,6 +3977,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > > ret = 0; > for_each_vma_range(vmi, vma, end) { > + struct userfaultfd_wake_range range; > + > cond_resched(); > > /* VMA not registered with userfaultfd. */ > @@ -3994,18 +3996,14 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > /* Prevent new userfaults from being queued after the wakeup. */ > vma_start_write(vma); > > - if (userfaultfd_missing(vma)) { > - /* > - * Wake any concurrent pending userfault while > - * we unregister, so they will not hang > - * permanently and it avoids userland to call > - * UFFDIO_WAKE explicitly. > - */ > - struct userfaultfd_wake_range range; > - range.start = start; > - range.len = vma_end - start; > - wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); > - } > + /* > + * Wake any concurrent pending userfault while we unregister, > + * so they will not hang permanently and it avoids userland to > + * call UFFDIO_WAKE explicitly. > + */ > + range.start = start; > + range.len = vma_end - start; > + wake_userfault(ctx, &range); > > vma = userfaultfd_clear_vma(&vmi, prev, vma, > start, vma_end); > > -- > 2.43.0 > -- Sincerely yours, Mike.