This is a note to let you know that I've just added the patch titled powerpc/mm/hugetlb: Filter out hugepage size not supported by page table layout to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-mm-hugetlb-filter-out-hugepage-size-not-supported-by-page-table-layout.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sun Mar 18 16:55:33 CET 2018 From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Date: Tue, 21 Mar 2017 22:59:56 +0530 Subject: powerpc/mm/hugetlb: Filter out hugepage size not supported by page table layout From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> [ Upstream commit a525108cf1cc14651602d678da38fa627a76a724 ] Without this if firmware reports 1MB page size support we will crash trying to use 1MB as hugetlb page size. echo 300 > /sys/kernel/mm/hugepages/hugepages-1024kB/nr_hugepages kernel BUG at ./arch/powerpc/include/asm/hugetlb.h:19! ..... .... [c0000000e2c27b30] c00000000029dae8 .hugetlb_fault+0x638/0xda0 [c0000000e2c27c30] c00000000026fb64 .handle_mm_fault+0x844/0x1d70 [c0000000e2c27d70] c00000000004805c .do_page_fault+0x3dc/0x7c0 [c0000000e2c27e30] c00000000000ac98 handle_page_fault+0x10/0x30 With fix, we don't enable 1MB as hugepage size. bash-4.2# cd /sys/kernel/mm/hugepages/ bash-4.2# ls hugepages-16384kB hugepages-16777216kB Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/mm/hugetlbpage.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -765,6 +765,24 @@ static int __init add_huge_page_size(uns if ((mmu_psize = shift_to_mmu_psize(shift)) < 0) return -EINVAL; +#ifdef CONFIG_PPC_BOOK3S_64 + /* + * We need to make sure that for different page sizes reported by + * firmware we only add hugetlb support for page sizes that can be + * supported by linux page table layout. + * For now we have + * Radix: 2M + * Hash: 16M and 16G + */ + if (radix_enabled()) { + if (mmu_psize != MMU_PAGE_2M) + return -EINVAL; + } else { + if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G) + return -EINVAL; + } +#endif + BUG_ON(mmu_psize_defs[mmu_psize].shift != shift); /* Return if huge page size has already been setup */ Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are queue-4.9/mm-fix-false-positive-vm_bug_on-in-page_cache_-get-add-_speculative.patch queue-4.9/powerpc-mm-hugetlb-filter-out-hugepage-size-not-supported-by-page-table-layout.patch