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From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Alex Bee <knaerzche@gmail.com>, Will Deacon <will@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases)
Date: Wed, 25 Aug 2021 13:54:45 +0300	[thread overview]
Message-ID: <YSYhdT+fP59b17GE@kernel.org> (raw)
In-Reply-To: <b720e7c8-ca44-0a25-480b-05bf49d03c35@redhat.com>

On Wed, Aug 25, 2021 at 12:38:31PM +0200, David Hildenbrand wrote:
> On 25.08.21 12:20, Catalin Marinas wrote:
>
> > I can see the documentation for pfn_valid() does not claim anything more
> > than the presence of an memmap entry. But I wonder whether the confusion
> > is wider-spread than just the DMA code. At a quick grep, try_ram_remap()
> > assumes __va() can be used on pfn_valid(), though I suspect it relies on
> > the calling function to check that the resource was RAM. The arm64
> > kern_addr_valid() returns true based on pfn_valid() and kcore.c uses
> > standard memcpy on it, which wouldn't work for I/O (should we change
> > this check to pfn_is_map_memory() for arm64?).
> 
> kern_addr_valid() checks that there is a direct map entry, and that the
> mapped address has a valid mmap. (copied from x86-64)
> 
> Would you expect to have a direct map for memory holes and similar (IOW,
> !System RAM)?

I don't see where will it bail out for an IOMEM mapping before doing the
pfn_valid() check...
 
-- 
Sincerely yours,
Mike.

WARNING: multiple messages have this Message-ID (diff)
From: Mike Rapoport <rppt@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Alex Bee <knaerzche@gmail.com>, Will Deacon <will@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases)
Date: Wed, 25 Aug 2021 13:54:45 +0300	[thread overview]
Message-ID: <YSYhdT+fP59b17GE@kernel.org> (raw)
In-Reply-To: <b720e7c8-ca44-0a25-480b-05bf49d03c35@redhat.com>

On Wed, Aug 25, 2021 at 12:38:31PM +0200, David Hildenbrand wrote:
> On 25.08.21 12:20, Catalin Marinas wrote:
>
> > I can see the documentation for pfn_valid() does not claim anything more
> > than the presence of an memmap entry. But I wonder whether the confusion
> > is wider-spread than just the DMA code. At a quick grep, try_ram_remap()
> > assumes __va() can be used on pfn_valid(), though I suspect it relies on
> > the calling function to check that the resource was RAM. The arm64
> > kern_addr_valid() returns true based on pfn_valid() and kcore.c uses
> > standard memcpy on it, which wouldn't work for I/O (should we change
> > this check to pfn_is_map_memory() for arm64?).
> 
> kern_addr_valid() checks that there is a direct map entry, and that the
> mapped address has a valid mmap. (copied from x86-64)
> 
> Would you expect to have a direct map for memory holes and similar (IOW,
> !System RAM)?

I don't see where will it bail out for an IOMEM mapping before doing the
pfn_valid() check...
 
-- 
Sincerely yours,
Mike.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-08-25 10:54 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24 13:40 [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases) Alex Bee
2021-08-24 13:40 ` Alex Bee
2021-08-24 17:37 ` Catalin Marinas
2021-08-24 17:37   ` Catalin Marinas
2021-08-24 18:06   ` Robin Murphy
2021-08-24 18:06     ` Robin Murphy
2021-08-24 18:28   ` Mike Rapoport
2021-08-24 18:28     ` Mike Rapoport
2021-08-24 18:46     ` Robin Murphy
2021-08-24 18:46       ` Robin Murphy
2021-08-24 18:59       ` David Hildenbrand
2021-08-24 18:59         ` David Hildenbrand
2021-08-25 10:20         ` Catalin Marinas
2021-08-25 10:20           ` Catalin Marinas
2021-08-25 10:28           ` Will Deacon
2021-08-25 10:28             ` Will Deacon
2021-08-25 10:32             ` Will Deacon
2021-08-25 10:32               ` Will Deacon
2021-08-25 10:33             ` Robin Murphy
2021-08-25 10:33               ` Robin Murphy
2021-08-25 10:38           ` David Hildenbrand
2021-08-25 10:38             ` David Hildenbrand
2021-08-25 10:54             ` Mike Rapoport [this message]
2021-08-25 10:54               ` Mike Rapoport
2021-08-25 10:55             ` Catalin Marinas
2021-08-25 10:55               ` Catalin Marinas
2021-08-25 11:12               ` David Hildenbrand
2021-08-25 11:12                 ` David Hildenbrand
2021-08-25 17:15                 ` Catalin Marinas
2021-08-25 17:15                   ` Catalin Marinas
2021-08-25 10:58             ` Robin Murphy
2021-08-25 10:58               ` Robin Murphy
2021-08-25 11:21               ` David Hildenbrand
2021-08-25 11:21                 ` David Hildenbrand
2021-08-25 10:52           ` Mike Rapoport
2021-08-25 10:52             ` Mike Rapoport
2021-09-17 21:22           ` Mike Rapoport
2021-09-17 21:22             ` Mike Rapoport
2021-09-18  5:18             ` Christoph Hellwig
2021-09-18  5:18               ` Christoph Hellwig
2021-09-18  8:37               ` Mike Rapoport
2021-09-18  8:37                 ` Mike Rapoport
2021-09-18 11:39                 ` Mike Rapoport
2021-09-18 11:39                   ` Mike Rapoport
2021-09-20 10:57                   ` Catalin Marinas
2021-09-20 10:57                     ` Catalin Marinas
2021-09-21  8:20                     ` Christoph Hellwig
2021-09-21  8:20                       ` Christoph Hellwig
2021-09-21  9:34                       ` Mike Rapoport
2021-09-21  9:34                         ` Mike Rapoport
2021-09-21 15:38                         ` Christoph Hellwig
2021-09-21 15:38                           ` Christoph Hellwig
2021-09-22  7:22                           ` Mike Rapoport
2021-09-22  7:22                             ` Mike Rapoport
2021-09-20 11:13               ` David Hildenbrand
2021-09-20 11:13                 ` David Hildenbrand
2021-08-24 20:14     ` Alex Bee
2021-08-24 20:14       ` Alex Bee
2021-08-25  4:39       ` Mike Rapoport
2021-08-25  4:39         ` Mike Rapoport
2021-08-25 10:00         ` Alex Bee
2021-08-25 10:00           ` Alex Bee
2021-08-24 20:07   ` Alex Bee
2021-08-24 20:07     ` Alex Bee

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