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d=linux-foundation.org; s=korg; t=1688863581; bh=fY53z6Onsmv3GKKfwc+3hC5M+1dggPKtLgeptAzv1fI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RmiaA/VzS9j6yirmr9X0dZ8m2E6vZJLjygrcSPtL6md5k6YOEhR3LNj0bB/mLCx4W vkswlziN5+2UT6w0rShS84zGu0pXfzKXW1DEB8AxCJ8bQ3Oj9KbEfHjmYjSMIyzYru JhbRKhNYLqdL7Xq9yXFCnvz83LBjcMbn/wplaNwQ= Date: Sat, 8 Jul 2023 17:46:20 -0700 From: Andrew Morton To: Muchun Song Cc: Muchun Song , Mike Kravetz , Linux Memory Management List , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: hugetlb_vmemmap: fix a race between vmemmap pmd split Message-Id: <20230708174620.8ef2109908f9606f3e4c090e@linux-foundation.org> In-Reply-To: <63EDE3B6-B0AD-4D67-8EC6-FC8AE627E352@linux.dev> References: <20230707033859.16148-1-songmuchun@bytedance.com> <20230707123844.adf56ba3e0d000f6da431494@linux-foundation.org> <63EDE3B6-B0AD-4D67-8EC6-FC8AE627E352@linux.dev> 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-Rspamd-Queue-Id: C40E0160005 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: cmnb46y8ed5upjdu7kwrqwn4pby9pjxq X-HE-Tag: 1688863582-842277 X-HE-Meta: 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 k9jnDxwk c7nrj57LypC2P0ftt0+Qplm6lTda9KSTeMc1NFd3qRdT6MHNd3GQcjx69WOXZVkqRzFmiPkZE0gzCqB/dNnKQy3eg9nXl0lpcoRsBIKLhlwmE4JzCv+OMNPThCzYgxjSqgyLl+wZmlt+5Jt7vhf5Hq6ULPlc7JfPcwxhl4Ba3Ifhps6R/k9FJDI/V1F2c9tqr/yAr/unoJXleYhKhSvmmGh4ZHwD306Qnn64VsQpXahA4tXXCsgHaNegMnGVFXseIVDj7RafFHGWmrIhhzvZdyCoNooBbqb/Wg5h2zI87gDOE5cyvpF+X1CSwNLV5CC/eg6vMFNYNoVQw8fq1CbmT9zxUZeK4Dk5zlK6r1v2J7PcRpBUE+OedvrzoE4RlM0mUV373pz3bXZSCIRveZUeM/8ltVvHToKhS4DBF3CHaiLs5IRM18nEc3EFyxlFAge/ud+/Dy3Ub7bJlqDrLl039sS0+10m0Vnx2BrPFZeRaSDoO3RA= 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: On Sat, 8 Jul 2023 09:42:57 +0800 Muchun Song wrote: > > > > On Jul 8, 2023, at 03:38, Andrew Morton wrote: > > > > On Fri, 7 Jul 2023 11:38:59 +0800 Muchun Song wrote: > > > >> The local variable @page in __split_vmemmap_huge_pmd() to obtain a pmd > >> page without holding page_table_lock may possiblely get the page table > >> page instead of a huge pmd page. The effect may be in set_pte_at() > >> since we may pass an invalid page struct, if set_pte_at() wants to > >> access the page struct (e.g. CONFIG_PAGE_TABLE_CHECK is enabled), it > >> may crash the kernel. So fix it. And inline __split_vmemmap_huge_pmd() > >> since it only has one user. > > > > Is this likely enough to justify a backport? > > > > I'm thinking "add cc:stable and merge into 6.6-rc1", so it hits -stable > > after a couple of months of testing. > > > > Hi Andrew, > > It is better to backport it to stable. Could you help me add it? > I have added cc:stable to this and I have staged it for 6.6-rc1.