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c=relaxed/simple; d=linux-foundation.org; s=korg; t=1694639525; bh=yNmnijX9dDFu7LZaZLAVZkns4JfXfNJbeOtM0K2Q1os=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WjCB7spDz7jk+KVHyubRrehdvmIsI1nemP+0f/RbXeFyfSyIcNKgXgwgIZtNSfcbO byAhITtR1UTjgibP+ZvN6UrwiH7qTutQvyl4LXQbMc1zScMusxJL120q9eCt9DCPRY 9IIDet2XsibUTQyVS2rluIMttOLpeBFl+seuKrLg= Date: Wed, 13 Sep 2023 14:12:04 -0700 From: Andrew Morton To: Zi Yan Cc: Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, Thomas Bogendoerfer , "Matthew Wilcox (Oracle)" , David Hildenbrand , Mike Kravetz , Muchun Song , "Mike Rapoport (IBM)" Subject: Re: [PATCH v3 0/5] Use nth_page() in place of direct struct page manipulation Message-Id: <20230913141204.b32ad42ac917c0e393d82a24@linux-foundation.org> In-Reply-To: <20230913201248.452081-1-zi.yan@sent.com> References: <20230913201248.452081-1-zi.yan@sent.com> 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: 4C9BE180016 X-Rspam-User: X-Stat-Signature: brh8sw3kukifa6nfjnctgdrbd5jmd48d X-Rspamd-Server: rspam03 X-HE-Tag: 1694639528-157924 X-HE-Meta: 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 icPT6h9y VnvOicoVp28OEmVKwRUjKJEIk+A0QsWguISRnoRLwgIpxc+dGqZq3E9nWajMqeXzAfvCwJLbkhDrj2zVktyflPlpccGUKDvS1zhwpO8BAVG9uSuvbBr2VcXvvTBSMuZsai16who/iogR0fMxxo8TQRCD+MoOoKhUQYt7JcIUVMZVKhD/uBm/wZh5ZHgwIe6wCDD7gNGiYjNAm7AUv3G19NQGkorL4w006gHfJnVOWdJ8UD0Zm/90fILeZZnhlXSvvEDqSwi6XsT9oJ3++CQS7yZ13O6KBgshBrhjo1n1c5ZE5PJsnnVUK42ZhNwaGRofVeJLnDDD3qUaY+KGY4sj9i3FusmOQBBRGkHtfgBnOCG2V40Vop9eFdZIpvfS8zfyQwYPHW4RE1xk25voFlJVPiuTZvYn1YhHmqFGQjSPab87lat4h7VPI0x3tXQ== 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 Wed, 13 Sep 2023 16:12:43 -0400 Zi Yan wrote: > On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be > contiguous, since each memory section's memmap might be allocated > independently. hugetlb pages can go beyond a memory section size, thus > direct struct page manipulation on hugetlb pages/subpages might give > wrong struct page. Kernel provides nth_page() to do the manipulation > properly. Use that whenever code can see hugetlb pages. for (each patch) { Can we please explain why -stable backporting is recommended? Such an explanation will, as always, include a description of the user-visible effects of the bug. Some of the Fixes: targets are very old: 5 years. Has something changed to bring these flaws to light? Or is it from code inspection? } Thanks.