From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9DF95364925 for ; Sun, 2 Aug 2026 07:40:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785656439; cv=none; b=V+xi87IZV1958SSNhK0WhGjPOC17otha2GyGNlZUVJoX/EiRMh6EUon4mcQPOufrLyZnqe8sNao/AI5TGfSFIim+imfEuNRJc31LgyZBMVlXHTaz757BxIxFZZSa1CAy1dttut338R/iEPoCdujcR9AGvfoOjPEfjxKpiOeclLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785656439; c=relaxed/simple; bh=SzGXVLHzn3c+fhf9I0bDVUsfpdR6jzd0P+X/+3T7HTo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nE3xtRktwgBY7RZmCjNQyND7cFZGEeNDK83zX3cyuhtIXeL+wT2Vt/EAng/KpFy4vDFhK4xQ6PV0iUNre7WpA5X8OTx6gHTSfKPiqKvsr0RM1faGSBr5GWwUMbbopxBaSzJpTXakWV0M35rAsFpykBmOQwRqavlOZ/zD3EpJ4+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M/4JPm5S; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M/4JPm5S" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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)