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b=omfbEecqCNV0u4fSV0wkn2rFqgPiiBk4KaDv4YrQCn79QKoxIhov9oFY3gDdb+fWl wJyWcOOO2ZGtH8MurIhycraTkt6JqcRGiO7RiPdYH2j0Co7cyUD0mtRaaN8+KEQbzE D0TL+xc7riC060HBhXRj/FulcXdfJqkFBWlA98IQ= Date: Thu, 5 Jun 2025 18:12:42 -0700 From: Andrew Morton To: Ge Yang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 21cnbao@gmail.com, david@redhat.com, baolin.wang@linux.alibaba.com, muchun.song@linux.dev, osalvador@suse.de, liuzixing@hygon.cn Subject: Re: [PATCH V2] mm/hugetlb: remove unnecessary holding of hugetlb_lock Message-Id: <20250605181242.54767f38223f9ebd4c379ccb@linux-foundation.org> In-Reply-To: References: <1748317010-16272-1-git-send-email-yangge1116@126.com> <20250604154754.a30e327c3f1640173c8b9cb8@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: xp6fyw6ycritcxmjjwdgeosssujecwwu X-Rspamd-Queue-Id: 9A93A40007 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1749172365-297220 X-HE-Meta: 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 IjN2qO7G HT6IWrBnKhnwBSpaJPSxpqaQzYEhK7yh0pH6ykhjD8xyuu4+A3XKpVLxprhbyZd0+Iddg8MNQtVl4bENEN9V0QMXgWr8bn59xYd3pFyfXPAfQlchxiT0tx4AzeQNNN9Wb+JqcPOJavGfpP/72IIaKMjw5rl+DiCoR+cK44FuwrOyQDGNgK0DhwWB/RyaPufRqpZCLjiBVzWaVJX2XIcZd6nQkJxtjDrybBoh/rh32yXOMGTMRv4v2A3WN4uOdc0+7dT6D/YXOZBaDTS92L6/bs0q0Uz72bARS/ouYxHGB7uKMbJQUCTLVc2buzykV29mFWUe2+/CjM4vTyJOdKgr1KFiG8lUoSGm+waxyHhztLG5P5LxneSuoOHTSy2ZQ6TtC8WLanD3sK8Ms5t3eBhLUStXT4Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 5 Jun 2025 08:44:09 +0800 Ge Yang wrote: > > This change addresses a possible performance issue which was introduced > > by 113ed54ad276 ("mm/hugetlb: fix kernel NULL pointer dereference when > > replacing free hugetlb folios"). 113ed54ad276 was added recently and > > was cc:stable. > > > > David said: > > https://lkml.kernel.org/r/87521d93-cc03-480d-a2ef-3ef8c84481c9@redhat.com > > > > > > Question is, will that bugfix's performance impact be sufficiently > > serious for us to also backport this new patch? > > In some low-probability scenarios, there could be severe impacts. For > example, when multiple CPUs execute the replace_free_hugepage_folios() > function simultaneously. It seems that we need to backport this new > patch. Thank you. OK, thanks. I added Fixes: 113ed54ad276 ("mm/hugetlb: fix kernel NULL pointer dereference when replacing free hugetlb folios") Cc: and moved this to the mm-hotfixes pile. I'll keep it there for a week or two for review/test. Once it goes upstream, this should propagate into 6.15.x.