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 50C5FECAAA1 for ; Fri, 28 Oct 2022 09:39:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5R9IySUrqqU2LBmzCaWBYsYmK3MStOCYnsgIFIrmK4w=; b=mCVlJ4qOK7WIXm xJFriQXkmhdkd63znxN6N4N0VCWNyb0gVfgW4j1TgJdHiVkP064HvzR6JjOynT1t3gRXjSxV38L2C pBYr5wufTAUEDJcGlHdrEp07Pr8TyGpN0hsF02zZ8m3yQhQWd7qA/HqySFwKnNsfmkLM2wgpP9YNo iPqhFC7VMZmXahByL+8nYoWhOC1kA2GRMfpEf7NzHwUmvrOowMGf3w1HgSMX9ZHcMNAcHqoGZGm6l 83J7h3jE8hfHUF+30i8pH/j6C8nqlvqA7cvDJz2kNQkbd34n90M7KkMtz4wBpl5eINlYv0vZ/Kh1L c84e/ctTTWpqAf4ik+gQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ooLoP-00GN5m-Lp; Fri, 28 Oct 2022 09:38:01 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ooLoM-00GN4V-Aj for linux-arm-kernel@lists.infradead.org; Fri, 28 Oct 2022 09:38:00 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9F586B828C6; Fri, 28 Oct 2022 09:37:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C721FC433D6; Fri, 28 Oct 2022 09:37:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666949875; bh=B2NfzUaV675feRonz5YD+4bCg4d2NepujeLeNBEjg6o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PCru372uBg5harVgYs8OEGPZaS4I8l8yiuIJIyluJcQpSrx32qo+s6YwHXC04VIYY gmsMbFJj58TTVPdpnCXEEZyBnxEXn1gh1nQ3dRU/WB8N0yvknM3Xh2LjjftHJ+7nsj 3VxugEDGzG9+GZryeNoeomn3WgQbIYlDTjC8aiu0= Date: Fri, 28 Oct 2022 11:37:52 +0200 From: Greg Kroah-Hartman To: Catalin Marinas Cc: Linus Torvalds , Arnd Bergmann , Will Deacon , Marc Zyngier , Andrew Morton , Herbert Xu , Ard Biesheuvel , Christoph Hellwig , Isaac Manjarres , Saravana Kannan , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 2/2] treewide: Add the __GFP_PACKED flag to several non-DMA kmalloc() allocations Message-ID: References: <20221025205247.3264568-1-catalin.marinas@arm.com> <20221025205247.3264568-3-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221028_023758_686961_04AC7E59 X-CRM114-Status: GOOD ( 39.92 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 28, 2022 at 11:37:18AM +0200, Greg Kroah-Hartman wrote: > On Thu, Oct 27, 2022 at 11:29:48PM +0100, Catalin Marinas wrote: > > On Wed, Oct 26, 2022 at 10:46:46AM -0700, Linus Torvalds wrote: > > > I think we should just stop bending over backwards over this, and say > > > "if your DMA isn't coherent, it's on your driver to mark its > > > allocations". > > [...] > > > That hardware may then be one of the one-off strange cases, but those > > > people with their masochistic tendencies can take the pain of "oh, now > > > I need to mark my broken driver with dma_alloc()". > > > > The driver is not necessarily broken. The same small kmalloc() in a USB > > driver can work fine on a fully coherent platform but if that chip ends > > up on a SoC that doesn't support coherent DMA, it needs bigger kmalloc() > > alignment. The driver could check if it's coherent but that's more of an > > arch detail that the driver shouldn't care about. If we define a new API > > like dma_alloc() and drivers don't use it, that's when we can claim they > > are broken. > > > > A further optimisation would be for dma_alloc() to take a struct device > > pointer and check dev_is_dma_coherent() before deciding to align the > > size, though this doesn't work when the allocation place cannot tell the > > destination device (e.g. alloc_skb(), though these buffers are > > cacheline-aligned already). > > > > Reading up on coccinelle to see if I can make this transition easier. If > > not, I'll probably go back to bouncing. > > bouncing? > > sparse is your friend here, here's a tiny patch that if you apply and > then build the kernel with sparse will show up all the USB driver > changes that are needed. (note, sample code only, does not fully work > yet as there are no .c changes made). > > I suggest we add something like this now, work on fixing up all of the > drivers for 6.2-rc1, and then you can add the backend allocator changes > after that. A few rounds of 'make allmodconfig' will show us the places > needing to be fixed up and 0-day will help out with that as well. > > Yes it's a lot, but it gives us a fighting chance to do the right thing > going forward with regards to knowing what "type" of memory needs to be > allocated. And here's actually the patch... diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index eb0466236661..dbc8e013cdaf 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -23,6 +23,7 @@ # define __iomem __attribute__((noderef, address_space(__iomem))) # define __percpu __attribute__((noderef, address_space(__percpu))) # define __rcu __attribute__((noderef, address_space(__rcu))) +# define __dma __attribute__((noderef, address_space(__dma))) static inline void __chk_user_ptr(const volatile void __user *ptr) { } static inline void __chk_io_ptr(const volatile void __iomem *ptr) { } /* context/locking */ @@ -50,6 +51,7 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { } # define __iomem # define __percpu BTF_TYPE_TAG(percpu) # define __rcu +# define __dma # define __chk_user_ptr(x) (void)0 # define __chk_io_ptr(x) (void)0 /* context/locking */ diff --git a/include/linux/usb.h b/include/linux/usb.h index 9ff1ad4dfad1..5f847c921802 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -1576,7 +1576,7 @@ struct urb { unsigned int stream_id; /* (in) stream ID */ int status; /* (return) non-ISO status */ unsigned int transfer_flags; /* (in) URB_SHORT_NOT_OK | ...*/ - void *transfer_buffer; /* (in) associated data buffer */ + void __dma *transfer_buffer; /* (in) associated data buffer */ dma_addr_t transfer_dma; /* (in) dma addr for transfer_buffer */ struct scatterlist *sg; /* (in) scatter gather buffer list */ int num_mapped_sgs; /* (internal) mapped sg entries */ @@ -1616,7 +1616,7 @@ static inline void usb_fill_control_urb(struct urb *urb, struct usb_device *dev, unsigned int pipe, unsigned char *setup_packet, - void *transfer_buffer, + void __dma *transfer_buffer, int buffer_length, usb_complete_t complete_fn, void *context) @@ -1646,7 +1646,7 @@ static inline void usb_fill_control_urb(struct urb *urb, static inline void usb_fill_bulk_urb(struct urb *urb, struct usb_device *dev, unsigned int pipe, - void *transfer_buffer, + void __dma *transfer_buffer, int buffer_length, usb_complete_t complete_fn, void *context) @@ -1687,7 +1687,7 @@ static inline void usb_fill_bulk_urb(struct urb *urb, static inline void usb_fill_int_urb(struct urb *urb, struct usb_device *dev, unsigned int pipe, - void *transfer_buffer, + void __dma *transfer_buffer, int buffer_length, usb_complete_t complete_fn, void *context, @@ -1766,10 +1766,10 @@ static inline int usb_urb_dir_out(struct urb *urb) int usb_pipe_type_check(struct usb_device *dev, unsigned int pipe); int usb_urb_ep_type_check(const struct urb *urb); -void *usb_alloc_coherent(struct usb_device *dev, size_t size, +void __dma *usb_alloc_coherent(struct usb_device *dev, size_t size, gfp_t mem_flags, dma_addr_t *dma); void usb_free_coherent(struct usb_device *dev, size_t size, - void *addr, dma_addr_t dma); + void __dma *addr, dma_addr_t dma); #if 0 struct urb *usb_buffer_map(struct urb *urb); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel