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Howlett" , Kyle Zeng , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/userfaultfd: only allocate anon_vma in CoW mappings Message-ID: References: <20261014-copy_hugetlb_page_range-v1-1-5b68e03fe7fe@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 5A63E1C0009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: na7pgjw3iekaczojddra66nmqn67zowx X-HE-Tag: 1792055132-933483 X-HE-Meta: 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 nd/rQ4t1 kCDP9kdiTp3i0o6WSJjVSqJxR+0ANXb7Jsf1m7DkD21BWoHMMjdoP79lU9Gqb3idL6CA4EXYR9p02xbfHin1LkkPC7hs0s6OzdRADxFu3zjihZgq42bV8DevCsheMRl0reNBqjspcS5Z5YnQBszFVSMv3LRBW1k6P/IlBf0pdt9JS/tLvWor+m+VRMmeKsUQ0uYU3xnvvJli4Lkz2xPC7ZNE7cCVrbDi9ZwIYUOYXxps31UNPCiFO+pSxZ1K+yFZ/0/mgXg/cD1Y9kghEDGYbl8I0RKhISv5KLfPGLAvDgtxJakA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Oct 14, 2026 at 08:29:35PM +0200, David Hildenbrand (Arm) wrote: > > Hmm really? Is it possible to do that without the hugetlb lock? > > Yes, we don't have to sync against PMD sharing if PMD sharing is impossible. Ahhh I see. > Will send that out for the next cycle. Looks sane! > > > It'd be good in general if we could get rid of that lock as a whole :) but maybe > > dreaming. > > Yeah :) I will probably have to go and look at that more deeply for mmap_prepare/scalable CoW reasons. I will wear goggles... :) -- Cheers, Lorenzo