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| author | Ming Lei <ming.lei@canonical.com> | 2013-10-31 16:34:17 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-11-13 12:01:49 +0900 |
| commit | 366f8a3ab0757921c4a925f7248e8c3f120305f9 (patch) | |
| tree | 93fe862e9cd6a7fbf07894442452f15c8f541855 /lib | |
| parent | 10ff8e6bf05b639df6d68abe5351be5d0cc18e4d (diff) | |
| download | lwn-366f8a3ab0757921c4a925f7248e8c3f120305f9.tar.gz lwn-366f8a3ab0757921c4a925f7248e8c3f120305f9.zip | |
lib/scatterlist.c: don't flush_kernel_dcache_page on slab page
commit 3d77b50c5874b7e923be946ba793644f82336b75 upstream.
Commit b1adaf65ba03 ("[SCSI] block: add sg buffer copy helper
functions") introduces two sg buffer copy helpers, and calls
flush_kernel_dcache_page() on pages in SG list after these pages are
written to.
Unfortunately, the commit may introduce a potential bug:
- Before sending some SCSI commands, kmalloc() buffer may be passed to
block layper, so flush_kernel_dcache_page() can see a slab page
finally
- According to cachetlb.txt, flush_kernel_dcache_page() is only called
on "a user page", which surely can't be a slab page.
- ARCH's implementation of flush_kernel_dcache_page() may use page
mapping information to do optimization so page_mapping() will see the
slab page, then VM_BUG_ON() is triggered.
Aaro Koskinen reported the bug on ARM/kirkwood when DEBUG_VM is enabled,
and this patch fixes the bug by adding test of '!PageSlab(miter->page)'
before calling flush_kernel_dcache_page().
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Tested-by: Simon Baatz <gmbnomis@gmail.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Tejun Heo <tj@kernel.org>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/scatterlist.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 6096e89bee55..8c2f278e5eb7 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -419,7 +419,8 @@ void sg_miter_stop(struct sg_mapping_iter *miter) if (miter->addr) { miter->__offset += miter->consumed; - if (miter->__flags & SG_MITER_TO_SG) + if ((miter->__flags & SG_MITER_TO_SG) && + !PageSlab(miter->page)) flush_kernel_dcache_page(miter->page); if (miter->__flags & SG_MITER_ATOMIC) { |