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Thu, 02 Apr 2026 20:50:34 -0700 (PDT) From: Qing Wang To: zhangdandan@uniontech.com Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot+37b7f6cd519f7fb8d32a@syzkaller.appspotmail.com, urezki@gmail.com, wangqing7171@gmail.com Subject: Re: [PATCH] mm/vmalloc: fix KMSAN uninit-value warning in decay_va_pool_node() Date: Fri, 3 Apr 2026 11:50:27 +0800 Message-Id: <20260403035027.2052972-1-wangqing7171@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B7334140006 X-Stat-Signature: xkhaacuoo8wzstuecykxgeubqhppm5jh X-Rspam-User: X-HE-Tag: 1775188235-559854 X-HE-Meta: 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 LRRkYf71 2BrUWGDSLKYpEISMtHhXUJvrdUp01EFlcclyXT4+rnPkG6Ia1HeUNMpC3rBUxMA6NSbrsOkziXq/xgKptHa3shPU3FVVFgzpGBwh1DhqnE364JHxBpV4GSJLn6G3B9vd4n0mQXh3xWhH5ZoTvbgnfHG7XPEma6tL6W3zQFL21UMWU6S9Hk9JRM0vQX6yofPsfhLOHePg6hTiJ6R1Uu9bQ30G3mwmJ6foAvrAIxeM2s1CIbWMM74g5nKeosw== 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 at 11:30, Morduan Zang wrote: > 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. Thank you very much for the reminder. I realized that my patch does not fix the real issue(concurrent corruption of the list). Please ignore this patch and let's focus on analyzing this concurrency issue. --- Best Regards, Qing