On Mon, Apr 04, 2016 at 05:24:00PM +0200, Gerald Schaefer wrote: > In gather_pte_stats() a THP pmd is cast into a pte, which is wrong because the > layouts may differ depending on the architecture. On s390 this will lead to > inaccurate numap_maps accounting in /proc because of misguided pte_present() > and pte_dirty() checks on the fake pte. > > On other architectures pte_present() and pte_dirty() may work by chance, but > there may be an issue with direct-access (dax) mappings w/o underlying struct > pages when HAVE_PTE_SPECIAL is set and THP is available. In vm_normal_page() > the fake pte will be checked with pte_special() and because there is no > "special" bit in a pmd, this will always return false and the VM_PFNMAP | > VM_MIXEDMAP checking will be skipped. On dax mappings w/o struct pages, an > invalid struct page pointer would then be returned that can crash the kernel. > > This patch fixes the numa_maps THP handling by introducing new "_pmd" variants > of the can_gather_numa_stats() and vm_normal_page() functions. > > Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # v4.3+ What is the git commit id of this in Linus's tree? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html