| From 3d77b50c5874b7e923be946ba793644f82336b75 Mon Sep 17 00:00:00 2001 |
| From: Ming Lei <ming.lei@canonical.com> |
| Date: Thu, 31 Oct 2013 16:34:17 -0700 |
| Subject: lib/scatterlist.c: don't flush_kernel_dcache_page on slab page |
| |
| 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| lib/scatterlist.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/lib/scatterlist.c |
| +++ b/lib/scatterlist.c |
| @@ -419,7 +419,8 @@ void sg_miter_stop(struct sg_mapping_ite |
| 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) { |
