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Fri, 03 Apr 2026 11:30:17 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 17905748780237733269 From: Morduan Zang To: wangqing7171@gmail.com Cc: urezki@gmail.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+37b7f6cd519f7fb8d32a@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/vmalloc: fix KMSAN uninit-value warning in decay_va_pool_node() Date: Fri, 3 Apr 2026 11:30:17 +0800 Message-ID: X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260403025614.2032877-1-wangqing7171@gmail.com> References: <20260403025614.2032877-1-wangqing7171@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpip:uniontech.com:qybglogicsvrgz:qybglogicsvrgz6b-0 X-QQ-XMAILINFO: M4IGCaTLe0Qduh6c2pgyZUFkdPtWz8EyDz+Zhv7VL8IOmJ0XjO/JTuR0 +1LvYdZ/LZb5PAEabcxRVka93dVR3byvqa4OrHz6Xbf6zS5acbrYp6/aYgYZTY2lqGvnUyn Moo+v/MXCNdMpQN1uK2rkvq92L3QRXh5ZOEXnLm44MDMbs9fUjG81yzJFdUz+Cc/TteYFVp chcUjUlyINtA4BKG+uZmlWMJsdYr18ddZ/T4soCF9ViH4aacU27+tSsS4u5UdwcUSBKflC1 3diZI1QkEh4CLTVvNQPt9quBZ2Onoq4GkoLYzN9gtM6N16VrseDkJPn42s+bBG7J2EpUvzi lo1Tc81hN/RAfOhx3SY44Wwylyn8sLm8ky6jxG0wT+MdpfQKyjpE71se7wbHKPXB0j0DCsy KxmSxQeRt2apmvQZrpXZh126KGcQa921ia0qE4ADCPqzKKgp47ebWszIkbvun5/VhXp0/7w q047RNr/dE0vaPKanXFWNnUHUuLUJdgqyXW+IhmIjfTpA7JZ8L3Mqle9WwOU4BgZmgETrJS I4BZ6OeaKLTZUPa8Stp05mFWV+PCrApEkFp3K2+FJSveJuxBQGcLi0Oy0uZTqg8JwWoe8ZS 0j7bi3t7SoSRymXE4wl5jwrClIuVoPE+qA5HEqIZrhb3qwhFU0C+rKLFbN92bHprDJs9I3M c1RMAzJAHW2KFxoOOjXyhxus9Nyi4hPbrzhWH/5Bu0xFy98FS3Mu+i3rxro32+l7uKDi+Hm FEKSqXIPaTA/Fz1/MZu1NkM1uZx8bhPsKlU7K5qAPBHYxt/9/OronFa1AaZO0BBrjcpSIeC iyUTyzkyDYVr0EFqgIAwrBY2jiy9c+tzyAxKc1PnsorWHVOJapDw6/tm23wilZ9vxWHDTbl BldMwdOe0ZksiJ5MXfzKt9LSTWcw293gA3MqvvNihIV/u1UHj9nmCB8RXDgixSlboM/We13 VodICGxwdaYXQolRSiDyWHoJ8KwUU+/EIF6Lm/8r1Nz9wLbO5RHPbEteLMmZs0QRssHBsbk TuwBERcw== X-QQ-XMRINFO: Mp0Kj//9VHAxzExpfF+O8yhSrljjwrznVg== X-QQ-RECHKSPAM: 0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 745ABC0002 X-Stat-Signature: 6dd3sz88tj9n9kkpirtyikyroj3dgs7r X-Rspam-User: X-HE-Tag: 1775187042-421855 X-HE-Meta: U2FsdGVkX1/EF31vJA6DbF3q3dXi4sxNKP/QzfVC27TjYoc6mSJqnoSkQDbh9vSYYUXTPenftvmVga9km3LW1Ajzaw9vArxf5WPo5f6S/IUIhtM8A8cKuuXY1RusBNFllpa7itsJpUlK1zPZ/+fjtaCcAofkk4AMTy5e8xAfSTD9/rvY4tjBNT+cxTPYVuUcxxsSBWjzccl7e3IuUp7Ncn9YsSAE2ce1YTBQsw+ZwYzWUcmJxy7ImrNyLYoX0bpUMhGz/xKsaLP9CtR4caNpdt4pf2Gk4Nwde5VmshCWcbefNoX26Y4Rd4cn6BfQ/9fG9KFA8KLOQMfqHw6flai25aOvWNUxfiv6CE1/JmP1adr4h8e+HG+JueH9BDH1XRbGUrKWA2n9DCE7/glZAq/I+9eNTNraUEV51BUrLiop02h2dBG8nQpQLZQjJQTFjrE+zhXYSd/X0sOqr+Er5gdUKUGNWSw4R7k0N6dKRKwCPigXndO7hq0I0asyh1fcSkUg0RRD0nfNvNNOaw41w166OhR71hATD3O7dDYAIj4zsQP2zaxIytx0OKDHlXN9R/fJGCvvzN/K1mDe5ZLRLALp63oWCGqwNTWWwCaKDM49FplkVcQWXc+O8UR04LhmTZTsGLlDM4PpjOhoisrH8anZvvd90TqVFB5jbzh8KMhLIErxQSwBqhHKBOrLuzT90EF7aXIW0kf/Ix94BZ/W+DX/hQVEhn61yKra6VGEVjG9FsMZlQtmsnIUd0887vb8KlleXZLYYKz8dNQWBFpFMjDSVTPdzeWycqjRIsCY58rKm3RQSf4FnIN6+hvZRA4TDtWs/hSJ6LUH78LgqMvSslc8l9K3gMVBbpQbF2C37xIQDPH0myyAIlLsLD+a3TuFhqsLjkq/6xbJQLpHBisezN8TXupTSVzqn7jG42LLD8E2+INP1VbG7/pVe2qJOGLZ2DacJsN9Ykf7ylST3/mGKrL CZAbnEjT Cuuw5B1ZJ3CNjM87KYw10afZU85jsMPH8HmpS+vQcMl6/gYDpOYLijBIrGP4TOBM4VpXFoubzXctuUh4nexp0xdIuJjRhICjT0gKp7Ff7C8pslNRG5qr75eAwmfw5XrOUfLChvRIOCZldDE5fFPUAkfJ93uexuMBYJ4pbdXSF36SzpRsQnz0BFg5q/e1clg2qeWyNengtdm0rouudd07Ih2qnlTLjcMyl72ewJ6GFat5Z/sEcTERFz1uMFxytavwIpN8TD5D5SZA3UPKbA2wj2upCZy0JnC4q0SnFJTINcNjnqxZXEBU8BGjyT2LuVWlnmVjK0q0u/njsWaO46//Z3B0diPbpitbTR0q7GH+mGXemtWbd9dT8A7bi3eW8eR6l/+OxckkR8F4xSh8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 03 Apr 2026, Qing Wang wrote: > First, va->list is inserted into the list_head when insert_vmap_area() > calls link_va(). However, if find_va_links() returns NULL, link_va() > will not be called, leaving va->list uninitialized. > > Second, even if link_va() is called, list_add() will still invoke > __list_add_valid() which reads va->list fields (prev/next). Under KMSAN, > this will also report a same uninit-value error. Hi Qing, While adding INIT_LIST_HEAD(&va->list) in alloc_vmap_area() would indeed silence the KMSAN warning, I'm concerned that it might only be masking a deeper issue rather than fixing the root cause. It seems that the uninitialized access in decay_va_pool_node() suggests a potential race condition where nodes from a concurrently repopulated pool might be lost or the list structure could be incorrectly overwritten during list_replace_init(). Instead of just initializing the list head to satisfy KMSAN, should we consider modifying decay_va_pool_node() to avoid using list_replace_init() which might drop concurrent repopulate nodes? Perhaps using list_splice() or a proper merge of the leftover VAs would be a more robust fix for the underlying synchronization issue. What do you and Uladzislau think? Best regards, Morduang