All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Russell King <linux@armlinux.org.uk>, Guo Ren <guoren@kernel.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>, Helge Deller <deller@gmx.de>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>, Geoff Levand <geoff@infradead.org>,
	Paul Cercueil <paul@crapouillou.net>,
	Ulf Hansson <ulf.hansson@linaro.org>, Alex Shi <alexs@kernel.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-mmc@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-mm@kvack.org,
	linux-doc@vger.kernel.org
Subject: flush_kernel_dcache_page fixes and removal
Date: Mon, 12 Jul 2021 08:09:22 +0200	[thread overview]
Message-ID: <20210712060928.4161649-1-hch@lst.de> (raw)

Hi all,

while looking to convert the block layer away from kmap_atomic towards
kmap_local_page and prefeably the helpers that abstract it away I noticed
that a few block drivers directly or implicitly call
flush_kernel_dcache_page before kunmapping a page that has been written
to.  flush_kernel_dcache_page is documented to to be used in such cases,
but flush_dcache_page is actually required when the page could be in
the page cache and mapped to userspace, which is pretty much always the
case when kmapping an arbitrary page.  Unfortunately the documentation
doesn't exactly make that clear, which lead to this misused.  And it turns
out that only the copy_strings / copy_string_kernel in the exec code
were actually correct users of flush_kernel_dcache_page, which is why
I think we should just remove it and eat the very minor overhead in
exec rather than confusing poor driver writers.

Diffstat:
 Documentation/core-api/cachetlb.rst                    |   86 +++++++----------
 Documentation/translations/zh_CN/core-api/cachetlb.rst |    9 -
 arch/arm/include/asm/cacheflush.h                      |    4 
 arch/arm/mm/flush.c                                    |   33 ------
 arch/arm/mm/nommu.c                                    |    6 -
 arch/csky/abiv1/cacheflush.c                           |   11 --
 arch/csky/abiv1/inc/abi/cacheflush.h                   |    4 
 arch/mips/include/asm/cacheflush.h                     |    8 -
 arch/nds32/include/asm/cacheflush.h                    |    3 
 arch/nds32/mm/cacheflush.c                             |    9 -
 arch/parisc/include/asm/cacheflush.h                   |    8 -
 arch/parisc/kernel/cache.c                             |    3 
 arch/sh/include/asm/cacheflush.h                       |    8 -
 block/blk-map.c                                        |    2 
 drivers/block/ps3disk.c                                |    2 
 drivers/mmc/host/jz4740_mmc.c                          |    4 
 drivers/mmc/host/mmc_spi.c                             |    2 
 drivers/scsi/aacraid/aachba.c                          |    1 
 fs/exec.c                                              |    6 -
 include/linux/highmem.h                                |    5 
 lib/scatterlist.c                                      |    5 
 tools/testing/scatterlist/linux/mm.h                   |    1 
 22 files changed, 55 insertions(+), 165 deletions(-)

WARNING: multiple messages have this Message-ID
From: Christoph Hellwig <hch@lst.de>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Russell King <linux@armlinux.org.uk>, Guo Ren <guoren@kernel.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>, Helge Deller <deller@gmx.de>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>, Geoff Levand <geoff@infradead.org>,
	Paul Cercueil <paul@crapouillou.net>,
	Ulf Hansson <ulf.hansson@linaro.org>, Alex Shi <alexs@kernel.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-mmc@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-mm@kvack.org,
	linux-doc@vger.kernel.org
Subject: flush_kernel_dcache_page fixes and removal
Date: Mon, 12 Jul 2021 08:09:22 +0200	[thread overview]
Message-ID: <20210712060928.4161649-1-hch@lst.de> (raw)

Hi all,

while looking to convert the block layer away from kmap_atomic towards
kmap_local_page and prefeably the helpers that abstract it away I noticed
that a few block drivers directly or implicitly call
flush_kernel_dcache_page before kunmapping a page that has been written
to.  flush_kernel_dcache_page is documented to to be used in such cases,
but flush_dcache_page is actually required when the page could be in
the page cache and mapped to userspace, which is pretty much always the
case when kmapping an arbitrary page.  Unfortunately the documentation
doesn't exactly make that clear, which lead to this misused.  And it turns
out that only the copy_strings / copy_string_kernel in the exec code
were actually correct users of flush_kernel_dcache_page, which is why
I think we should just remove it and eat the very minor overhead in
exec rather than confusing poor driver writers.

Diffstat:
 Documentation/core-api/cachetlb.rst                    |   86 +++++++----------
 Documentation/translations/zh_CN/core-api/cachetlb.rst |    9 -
 arch/arm/include/asm/cacheflush.h                      |    4 
 arch/arm/mm/flush.c                                    |   33 ------
 arch/arm/mm/nommu.c                                    |    6 -
 arch/csky/abiv1/cacheflush.c                           |   11 --
 arch/csky/abiv1/inc/abi/cacheflush.h                   |    4 
 arch/mips/include/asm/cacheflush.h                     |    8 -
 arch/nds32/include/asm/cacheflush.h                    |    3 
 arch/nds32/mm/cacheflush.c                             |    9 -
 arch/parisc/include/asm/cacheflush.h                   |    8 -
 arch/parisc/kernel/cache.c                             |    3 
 arch/sh/include/asm/cacheflush.h                       |    8 -
 block/blk-map.c                                        |    2 
 drivers/block/ps3disk.c                                |    2 
 drivers/mmc/host/jz4740_mmc.c                          |    4 
 drivers/mmc/host/mmc_spi.c                             |    2 
 drivers/scsi/aacraid/aachba.c                          |    1 
 fs/exec.c                                              |    6 -
 include/linux/highmem.h                                |    5 
 lib/scatterlist.c                                      |    5 
 tools/testing/scatterlist/linux/mm.h                   |    1 
 22 files changed, 55 insertions(+), 165 deletions(-)

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

             reply	other threads:[~2021-07-12  6:11 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-12  6:09 Christoph Hellwig [this message]
2021-07-12  6:09 ` Christoph Hellwig
2021-07-12  6:09 ` [PATCH 1/6] mmc: JZ4740: remove the flush_kernel_dcache_page call in jz4740_mmc_read_data Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-07-19  8:15   ` Paul Cercueil
2021-07-19  8:15     ` Paul Cercueil
2021-08-04 11:12   ` Ulf Hansson
2021-08-04 11:12     ` Ulf Hansson
2021-08-04 11:12     ` Ulf Hansson
2021-07-12  6:09 ` [PATCH 2/6] mmc: mmc_spi: replace flush_kernel_dcache_page with flush_dcache_page Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-08-04 11:12   ` Ulf Hansson
2021-08-04 11:12     ` Ulf Hansson
2021-08-04 11:12     ` Ulf Hansson
2021-07-12  6:09 ` [PATCH 3/6] ps3disk: " Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-07-19  3:07   ` Geoff Levand
2021-07-19  3:07     ` Geoff Levand
2021-07-12  6:09 ` [PATCH 4/6] scatterlist: " Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-07-12  6:09 ` [PATCH 5/6] aacraid: remove an unused include Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-07-19  1:50   ` Martin K. Petersen
2021-07-19  1:50     ` Martin K. Petersen
2021-07-12  6:09 ` [PATCH 6/6] mm: remove flush_kernel_dcache_page Christoph Hellwig
2021-07-12  6:09   ` Christoph Hellwig
2021-07-12 23:56   ` Ira Weiny
2021-07-12 23:56     ` Ira Weiny
2021-07-12 19:24 ` flush_kernel_dcache_page fixes and removal Linus Torvalds
2021-07-12 19:24   ` Linus Torvalds
2021-07-12 19:24   ` Linus Torvalds
2021-07-13  5:46   ` Christoph Hellwig
2021-07-13  5:46     ` Christoph Hellwig
2021-07-13  8:46 ` Russell King (Oracle)
2021-07-13  8:46   ` Russell King (Oracle)
2021-07-13  9:11   ` Christoph Hellwig
2021-07-13  9:11     ` Christoph Hellwig
2021-07-19  5:38   ` Herbert Xu
2021-07-19  5:38     ` Herbert Xu
2021-07-19 15:42     ` Russell King (Oracle)
2021-07-19 15:42       ` Russell King (Oracle)
2021-07-14  3:13 ` Guo Ren
2021-07-14  3:13   ` Guo Ren
2021-07-14  3:13   ` Guo Ren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210712060928.4161649-1-hch@lst.de \
    --to=hch@lst.de \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexs@kernel.org \
    --cc=dalias@libc.org \
    --cc=deanbo422@gmail.com \
    --cc=deller@gmx.de \
    --cc=geoff@infradead.org \
    --cc=green.hu@gmail.com \
    --cc=guoren@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-csky@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-mmc@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=nickhu@andestech.com \
    --cc=paul@crapouillou.net \
    --cc=torvalds@linux-foundation.org \
    --cc=tsbogend@alpha.franken.de \
    --cc=ulf.hansson@linaro.org \
    --cc=ysato@users.sourceforge.jp \
    --subject='Re: flush_kernel_dcache_page fixes and removal' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.