From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0A297C55179 for ; Sun, 2 Aug 2026 07:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FBvTUsFpbqARD87S9WXjNTJXkVqbnPLRNoKntz2t7gk=; b=x6KqQzX91zbQ3BkjD0ToF2Yti6 /4Xv5VCN2Z0H0JxmU+F0PJcmOFZdA1UEHuO/iakBJw3Jn0CH0pS63yE4NGF0pRG3dXsB6aDiYN4bA p6aBX3PsCD7J9r8QL0T5gKtq9HpvNHKnCDnONbe2UTpsKDNxz3C7jysxESXF3mSwg73BuclWw9vdc 2OTGhzrcj63yvp9obrvHmcETx+9DhGG//lvWFcDCE3GJkuiggxO9n76R3q7EBb1ez+SVHhei9YQlW oGM3jXCnX6sCRlOJCPL9t8pteqiDH22G4lQUfFI4K3A0f1xlJphYp7C1v5RPkEzFyTYV9jH1EbR+E wuAiPMpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqQoK-0000000FSQm-3PTr; Sun, 02 Aug 2026 07:40:40 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqQoJ-0000000FSQP-2RpF for linux-arm-kernel@lists.infradead.org; Sun, 02 Aug 2026 07:40:39 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 8285860DD1; Sun, 2 Aug 2026 07:40:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A10831F00AC4; Sun, 2 Aug 2026 07:40:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785656438; bh=FBvTUsFpbqARD87S9WXjNTJXkVqbnPLRNoKntz2t7gk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M/4JPm5SGHOpNVts3WgVJP+6dIsG7yGugTjEgp26b2GYXzDF7dRr0o/BshxyGXjBG A6ivFWO18gSqdfGjn4Q7OOrf3tVuIn5v4wISp4ia268p77o4TLkMKIcbQ363UBls2Q HVsMwTyNv6byf2x6G65s86CdCUwBv3ShZtJ3scrvPSJUK8A0p47YbGrVKA5NGWWX8+ t2eyXR2uc3wykAoBD5g4hAeGe13u32Pt4h/+2sf4QCnuRb+dlPcqDZpdDTt2ZSvxBz wER5xw3zBBqPZ4mWv4Ml8+Os0+SUVuxKiOvnuT0PkJLdls7ddnrCY/xUD9pFflemFl YZ5q5Sz53ZaUA== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: x86@kernel.org, linux-arm-kernel@lists.infradead.org, surenb@google.com, liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, shakeel.butt@linux.dev, david@kernel.org, linux-kernel@vger.kernel.org, zhanghongru@xiaomi.com, willy@infradead.org, zhangbo56@xiaomi.com, "Barry Song (Xiaomi)" Subject: [RFC PATCH v1 2/2] arm64/mm: use VMA lock for kernel faults on user addresses Date: Sun, 2 Aug 2026 15:40:18 +0800 Message-Id: <20260802074018.73887-3-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260802074018.73887-1-baohua@kernel.org> References: <20260802074018.73887-1-baohua@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Use the VMA lock for kernel faults on user addresses. This also makes the existing code below meaningful: /* Quick path to respond to signals */ if (fault_signal_pending(fault, regs)) { if (!user_mode(regs)) goto no_context; return 0; } Right now, the code above is dead because !user_mode always takes the mmap_lock path. Co-developed-by: Bo Zhang Signed-off-by: Bo Zhang Signed-off-by: Barry Song (Xiaomi) --- arch/arm64/mm/fault.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 85e23388f9bb..241f1ab07ab3 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -607,6 +607,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, unsigned int mm_flags = FAULT_FLAG_DEFAULT; unsigned long addr = untagged_addr(far); struct vm_area_struct *vma; + bool uaccess = false; int si_code; int pkey = -1; @@ -663,6 +664,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, if (!insn_may_access_user(regs->pc, esr)) die_kernel_fault("access to user memory outside uaccess routines", addr, esr, regs); + uaccess = true; } if (is_pkvm_stage2_abort(esr)) { @@ -674,7 +676,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); - if (!(mm_flags & FAULT_FLAG_USER)) + if (!(mm_flags & FAULT_FLAG_USER) && !uaccess) goto lock_mmap; vma = lock_vma_under_rcu(mm, addr); -- 2.39.3 (Apple Git-146)