Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 3.5 33/78] lib/scatterlist.c: don't flush_kernel_dcache_page on slab page | Date | Mon, 25 Nov 2013 13:06:20 +0000 |
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3.5.7.26 -stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei <ming.lei@canonical.com>
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: Luis Henriques <luis.henriques@canonical.com> --- lib/scatterlist.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 6096e89..8c2f278 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) { -- 1.8.3.2
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