On Tue, 29 Oct 2013 00:20:05 +0800 Ming Lei <ming....@canonical.com> wrote:
> 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(). We should work out which kernel(s) need this patch. b1adaf65ba03 was merged in 2008, so presumably some more recent patch has exposed the problem, but I don't know what one that was. Help me out here? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
