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From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>, Ira Weiny <ira.weiny@intel.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm: call flush_dcache_page in memcpy_to_page and memzero_page
Date: Wed, 14 Jul 2021 07:28:41 +0200	[thread overview]
Message-ID: <20210714052841.GA6380@lst.de> (raw)
In-Reply-To: <20210713183123.699769a1b0ee95d69606c35d@linux-foundation.org>

On Tue, Jul 13, 2021 at 06:31:23PM -0700, Andrew Morton wrote:
> On Tue, 13 Jul 2021 07:52:30 +0200 Christoph Hellwig <hch@lst.de> wrote:
> 
> > memcpy_to_page and memzero_page can write to arbitrary pages, which could
> > be in the page cache or in high memory, so  call flush_kernel_dcache_pages
> > to flush the dcache.
> 
> I assume this presently is not known to cause any problems, but that
> some problems might be discovered in the future?  In which case,
> should we cc:stable?

This is a problem when using these helpers on dcache challeneged
architectures.  Right now there are just a few users, chances
are no one used the PC floppy drіver, the aha1542 driver for an ISA
SCSI HBA, and a few advanced and optional btrfs and ext4 features
on those platforms yet since the conversion.  So yes, stable would be
good.

  reply	other threads:[~2021-07-14  5:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-13  5:52 fix memcpy_to_page and memzero_page Christoph Hellwig
2021-07-13  5:52 ` [PATCH 1/2] mm: call flush_dcache_page in " Christoph Hellwig
2021-07-14  1:31   ` Andrew Morton
2021-07-14  5:28     ` Christoph Hellwig [this message]
2021-07-14  8:09   ` Ira Weiny
2021-07-13  5:52 ` [PATCH 2/2] mm: use kmap_local_page in memzero_page Christoph Hellwig

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