Commit b1adaf65ba ("[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 <[email protected]>
Reported-by: Aaro Koskinen <[email protected]>
Tested-by: Simon Baatz <[email protected]>
Cc: Russell King - ARM Linux <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Aaro Koskinen <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Cc: FUJITA Tomonori <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: <[email protected]> [3.2+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Ming Lei
3d77b50c58