From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (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 1EEFC33D6C3; Wed, 26 Nov 2025 18:55:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764183346; cv=none; b=KJihBXneVlW6aCjX2aa1OZTjHv7D2DLU2N5pYeGaOVIWPP2z6yk/f04aNfv69i3Ca7H95R3BAoTUMDtwWq5dSDgxiocru0l4VYM++2yGuRvlnH2h6OGyDL+qgYlPwRgPilbk1qNXW38189iWgCGc4ONVekvSJ7N5Fo9enbtQ7cg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764183346; c=relaxed/simple; bh=uY7HaMSJsv6SKAaOVRzKVfCOgnFK8BFUcRzVE+a+wVY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dd2mwDjngZbJsTmHfeCduAiLlJmFiF1+91buHARo+Ws5/z7sllWuXdbQAxzMBW5hg0xB7zpdkWQc6XH34i07nB6yw/U69cnDeTVZdCW+XmXkBSU7qf4gijzss1tUsbjldtoqAn+CmpZLYZo5qHwKgm4FwwlBAsJ+it7wegb1fr0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=g3nS6R4b; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="g3nS6R4b" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=MLgia25EvIAIBo0VY2I6S9Dk4/MSQiPdMJldJvpcdsU=; b=g3nS6R4bW6uQlx6Je24W9afEMH Em5LKt9oz497k9Gfvq/XJ6/fvEKedQW3YCWBUH4PKFDdicr4JXoufcWgeWK7ZSKU746ud4sumvmfV YFNnq6xLzJPiACvsBcuyfVcSUnV3OpxMuva5TL3RuNuU+TffZJW9CUynU/dVu/G8lWvJ3b7YIKkhz 9yZ6mCKUXqeuIpWgtJErxKkaN0GEn3IPqwa/y96rIxsDaXZooIrwB2XiggY7muOwYj/KzbZGUgbxZ SF/CXLaEIOq6KfcuVZfyq7VCgkA0OMCSds/ICAlTsKJdpjSM1Wvsnw4PrjBCCA8I8x400e1Wrl1WS zsOaQ43Q==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vOKg5-000000007j8-2ErT; Wed, 26 Nov 2025 18:55:45 +0000 Date: Wed, 26 Nov 2025 18:55:45 +0000 From: Al Viro To: Zizhi Wo Cc: jack@suse.com, brauner@kernel.org, hch@lst.de, akpm@linux-foundation.org, linux@armlinux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, wozizhi@huawei.com, yangerkun@huawei.com, wangkefeng.wang@huawei.com, pangliyuan1@huawei.com, xieyuanbin1@huawei.com Subject: Re: [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context Message-ID: <20251126185545.GC3538@ZenIV> References: <20251126090505.3057219-1-wozizhi@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251126090505.3057219-1-wozizhi@huaweicloud.com> Sender: Al Viro On Wed, Nov 26, 2025 at 05:05:05PM +0800, Zizhi Wo wrote: > under an RCU read-side critical section. In linux-mainline, arm/arm64 > do_page_fault() still has this problem: > > lock_mm_and_find_vma->get_mmap_lock_carefully->mmap_read_lock_killable. arm64 shouldn't hit do_page_fault() in the first place, and do_translation_fault() there will see that address is beyond TASK_SIZE and go straight to do_bad_area() -> __do_kernel_fault() -> fixup_exception(), with no messing with mmap_lock. Can anybody confirm that problem exists on arm64 (ideally - with reproducer)?