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Fri, 28 Nov 2025 10:26:11 +0800 (CST) Received: from kwepemj100009.china.huawei.com (unknown [7.202.194.3]) by mail.maildlp.com (Postfix) with ESMTPS id 0145F1A016C; Fri, 28 Nov 2025 10:28:01 +0800 (CST) Received: from DESKTOP-A37P9LK.huawei.com (10.67.109.17) by kwepemj100009.china.huawei.com (7.202.194.3) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 28 Nov 2025 10:27:59 +0800 From: Xie Yuanbin To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH v2 1/2] ARM/mm/fault: always goto bad_area when handling with page faults of kernel address Date: Fri, 28 Nov 2025 10:27:56 +0800 Message-ID: <20251128022756.9973-1-xieyuanbin1@huawei.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251127145127.qUXs_UAE@linutronix.de> References: <20251127145127.qUXs_UAE@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.67.109.17] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemj100009.china.huawei.com (7.202.194.3) X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 56D8C180004 X-Stat-Signature: spaubmnxumuhu58xyn8hubgibambij1s X-Rspam-User: X-HE-Tag: 1764296884-184542 X-HE-Meta: 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 pUlDlX+d 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 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 Thu, 27 Nov 2025 15:51:27 +0100, Sebastian Andrzej Siewior wrote: > What is with the patch I sent wrong? Hi, Sebastian Andrzej Siewior! There is nothing wrong with your patches, but when you submitted your patches, this bug has not been reportted: Link: https://lore.kernel.org/20251126090505.3057219-1-wozizhi@huaweicloud.com Your patches fixed the missing mitigation, but the aforementioned bug still exists. I think there might be a better solution that can fix both bugs at the same time. We had some discussions about this bug: Link: https://lore.kernel.org/CAHk-=wh1Wfwt9OFB4AfBbjyeu4JVZuSWQ4A8OoT3W6x9btddfw@mail.gmail.com Link: https://lore.kernel.org/20251126192640.GD3538@ZenIV Link: https://lore.kernel.org/aSeNtFxD1WRjFaiR@shell.armlinux.org.uk According to the discussion, it might be better to handle the kernel address fault directly, just like what x86 does, instead of finding VMA. Link: https://elixir.bootlin.com/linux/v6.18-rc7/source/arch/x86/mm/fault.c#L1473 ```c if (unlikely(fault_in_kernel_space(address))) do_kern_addr_fault(regs, error_code, address); else do_user_addr_fault(regs, error_code, address); ``` It seems your patches hasn't been merged into the linux-next branch yet. This patch is based on linux-next, so it doesn't include your modifications. This patch might conflict with your patch: Link: https://lore.kernel.org/20251110145555.2555055-2-bigeasy@linutronix.de so I'd like to discuss it with you. Thanks! Xie Yuanbin