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b=j+y/LT96GF5Yrb4iQ5H260+KTEB00Efqr/TA+1iKOCpi/wk+z3hdRpoh9BarM1RED DqmJyBb4RIOOKtTKriEKhVuAnzul74ZLMxxn+vGiGME+/e7Y5ZOVswy9NHDYMq6BdR cEei7b/KJZ4JAi17fbE6Sd/Ly3iEqoUJW5aABGx8= Date: Thu, 15 Aug 2024 22:07:09 -0700 From: Andrew Morton To: Uladzislau Rezki Cc: Michal Hocko , Barry Song <21cnbao@gmail.com>, Hailong Liu , Christoph Hellwig , Vlastimil Babka , Tangquan Zheng , stable@vger.kernel.org, Baoquan He , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH v1] mm/vmalloc: fix page mapping if vm_area_alloc_pages() with high order fallback to order 0 Message-Id: <20240815220709.47f66f200fd0a072777cc348@linux-foundation.org> In-Reply-To: References: <20240808122019.3361-1-hailong.liu@oppo.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-Stat-Signature: ze7h3i1w8obt7h7ap57azw7h8i5z61rb X-Rspam-User: X-Rspamd-Queue-Id: 6B78FA001A X-Rspamd-Server: rspam02 X-HE-Tag: 1723784833-639386 X-HE-Meta: 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 vvhRmb/M 5xguSbRo0f/gMFXdrvhFhflAYpbN4+62iiXC2Npoyo0USs25OP9b5iYq1gZ8VtTydOKbajeoX4PNmWzwhR1Yk5LeXp0E6T5BNXqyk2VqlMc8PB7rw+c/i4SFVVfPZTXDvUtSvMIog+rx4VpC8gv+h5D2rxL25Drp4NjWZrCugp6sciOAbXjhPl8ja1pBgs6dt1GpOsbSWt2sV5l0JAaTD4pzsB5xxeSVdWz0tA+78C+tN9lr6IoZ+Guo4zK9tducDYyze5+fR3GWi6aidz9gLC+LmCkkpYVcpjfioXI0rNpbizbHLF5cy0jlVSU4T9iUw/Ip1Yqh6eyvf3AXNn4OBRxDNwtqySmeC1swgfzMYNtYReO+DerCD2h0FOpb9TmYM6KIXcP3eJmk1PJv3Ti2icay7wZ23+C/lYovO 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 Fri, 9 Aug 2024 11:41:42 +0200 Uladzislau Rezki wrote: > > > Acked-by: Barry Song > > > > > > because we already have a fallback here: > > > > > > void *__vmalloc_node_range_noprof : > > > > > > fail: > > > if (shift > PAGE_SHIFT) { > > > shift = PAGE_SHIFT; > > > align = real_align; > > > size = real_size; > > > goto again; > > > } > > > > This really deserves a comment because this is not really clear at all. > > The code is also fragile and it would benefit from some re-org. > > > > Thanks for the fix. > > > > Acked-by: Michal Hocko > > > I agree. This is only clear for people who know the code. A "fallback" > to order-0 should be commented. It's been a week. Could someone please propose a fixup patch to add this comment?