From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 0D03617CA1B; Mon, 28 Oct 2024 08:41:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730104913; cv=none; b=VjToIdT5wkpJHVUNG9A75zKdXjyMEVXPt5e569+bpTMKpIQza/7HuyNRsNfNa6iO612ywNo25F9fEJIEERRIq2uSLJ4467pBEi037WN+rYMzMF8sofD9//YiQbJI/uaXykznXbM1vE72ILZkDfnIVhj7o3p20AgZtY4OpufgnGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730104913; c=relaxed/simple; bh=KTIfXUdYAvpwso49g1yYWYsZv6RvufQJe+aCEFcGvJ0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=VnSLucdwAyS3PRlBF16+LTzRpI4DJkzBSWUdJNZjrdSHvB4mAZJGeWvjH1WyJlWbTK+APld7EWiYhcNSUUXbI5T7izHPbcNEOJdI+YcrjPsk8qFpoYTbf+oVzkYl+WicmYk+13Ml9uZ7bVptZesCRMwzV4sAo8QpuJ0deV6O2LA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=x3TXW5jz; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=VQAr2k4I; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="x3TXW5jz"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="VQAr2k4I" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1730104909; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1H44vgesP1XQXrv9CcIfmLIuQ+1Lb7UWNVl5j+TBJ08=; b=x3TXW5jzTZtadCH2BFHWSDUQsinXPlK0IrDDFRy/3tNQK0hzy3RehZqmDb5+LDPS5kOzQc sjnMxY5k25sQYGXLGYjtF6Teg3B84jy/bMViihmY1+l351ebf71jlbT5IqfVe40dQneeB3 vKETQHeiYHoTnMEQ4/E9gkHBCmVSG0H21a4FRwH9RLTNgC4pNPkvjcWbza9iOzYXpTcOb6 NKB13JlaGMBXliD2Dq9Na5nEvaPDkQYWh7KYhQShbbhXtic1cULYTlUI4tJPwgU550RGvk lUPOTglWIlyyGcXjEuR58wOsJ4hJd0Zpv72EbpMDTC6edTBiAM+tatV4FIUG1A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1730104910; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1H44vgesP1XQXrv9CcIfmLIuQ+1Lb7UWNVl5j+TBJ08=; b=VQAr2k4I06KdONU7UIdNQErDeF0PPVIHebz4hNbPiOnA40OILCuO/XnqUe/puyjjeB+a6q D8khm6vUYCuFTgCQ== To: Hugh Dickins , Alexander Viro Cc: Andrew Morton , Christian Brauner , Matthew Wilcox , Christoph Hellwig , Kent Overstreet , "Darrick J. Wong" , Peter Zijlstra , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds Subject: Re: [PATCH] iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP In-Reply-To: References: Date: Mon, 28 Oct 2024 09:41:48 +0100 Message-ID: <874j4w4o1f.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Sun, Oct 27 2024 at 15:23, Hugh Dickins wrote: > generic/077 on x86_32 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y with highmem, > on huge=always tmpfs, issues a warning and then hangs (interruptibly): > > WARNING: CPU: 5 PID: 3517 at mm/highmem.c:622 kunmap_local_indexed+0x62/0xc9 > CPU: 5 UID: 0 PID: 3517 Comm: cp Not tainted 6.12.0-rc4 #2 > ... > copy_page_from_iter_atomic+0xa6/0x5ec > generic_perform_write+0xf6/0x1b4 > shmem_file_write_iter+0x54/0x67 > > Fix copy_page_from_iter_atomic() by limiting it in that case > (include/linux/skbuff.h skb_frag_must_loop() does similar). > > But going forward, perhaps CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is too > surprising, has outlived its usefulness, and should just be removed? It has caught real problems and as long as we have highmem support, it should stay IMO to provide test coverage. Thanks, tglx