From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B7B6F145333 for ; Wed, 7 Aug 2024 21:17:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723065425; cv=none; b=ZFqx7LRZY2I3lJ6gAQxMOz8DTqdqLx/T4lqwLh8yM2bwEytKyKf2ONUHGZZjFVOX7dP71AmcYMXsEUXfSPFtqehcwveDpsZfb4tdWKA20NSFVzuvW7gbVLs9KrB2XTulPKMLvA5WDnsveRof17V6agfRrj1mQW8jOv1+ZUX0X4M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723065425; c=relaxed/simple; bh=+gUpbSegd1rP99qLghMnsgBErS9zrHF45NWkbO3C0pc=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=BvkyPddqCLri2UXleL64qDJqijDfYceVw5QAmE7Kt7Zfm6B1y3Okde3+ahDgFpQ2sB0w5r2OvmTMcuaxQAeV18xh00jMfUXCvDqWhcm0Y6J0wCTiLqs6Wt9k5/W5Hm3tTfL7Iomjawn4eDdAs9SH81SSWI5S6WFeNjVfaUqerSU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=0TFKINsp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="0TFKINsp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43CC7C32781; Wed, 7 Aug 2024 21:17:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1723065425; bh=+gUpbSegd1rP99qLghMnsgBErS9zrHF45NWkbO3C0pc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=0TFKINspgpAlLabxd/er+hxRd2vgR0Zs5pOwaZjJoMxyXSkODwI2oFe2cXYsgU71q Run8TO4CZCIZS1bbMHvyICsWBdEqyNihC5Nqewyg+REZ3YSGiX6Jk1u9Z9eJt6Ocsv Ud42JWI0sqQqmHgCa6cvnF/vmd5PDgkW2tmTDDQA= Date: Wed, 7 Aug 2024 14:17:03 -0700 From: Andrew Morton To: Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Aneesh Kumar K . V" , Michael Ellerman , Oscar Salvador , Dan Williams , James Houghton , Matthew Wilcox , Nicholas Piggin , Rik van Riel , Dave Jiang , x86@kernel.org, Ingo Molnar , Rick P Edgecombe , "Kirill A . Shutemov" , linuxppc-dev@lists.ozlabs.org, Mel Gorman , Hugh Dickins , Borislav Petkov , David Hildenbrand , Thomas Gleixner , Vlastimil Babka , Dave Hansen , Christophe Leroy , Huang Ying Subject: Re: [PATCH v4 0/7] mm/mprotect: Fix dax puds Message-Id: <20240807141703.d641001ee14177ccf80a31d8@linux-foundation.org> In-Reply-To: <20240807194812.819412-1-peterx@redhat.com> References: <20240807194812.819412-1-peterx@redhat.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 7 Aug 2024 15:48:04 -0400 Peter Xu wrote: > > Dax supports pud pages for a while, but mprotect on puds was missing since > the start. This series tries to fix that by providing pud handling in > mprotect(). The goal is to add more types of pud mappings like hugetlb or > pfnmaps. This series paves way for it by fixing known pud entries. > > Considering nobody reported this until when I looked at those other types > of pud mappings, I am thinking maybe it doesn't need to be a fix for stable > and this may not need to be backported. I would guess whoever cares about > mprotect() won't care 1G dax puds yet, vice versa. I hope fixing that in > new kernels would be fine, but I'm open to suggestions. Yes, I'm not sure this is a "fix" at all. We're implementing something which previously wasn't there. Perhaps the entire series should be called "mm: implement mprotect() for DAX PUDs"?