On 03/14/2018 02:46 PM, Andrew Morton wrote: > On Wed, 14 Mar 2018 11:52:51 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: > >> On 03/13/2018 11:15 PM, kbuild test robot wrote: >>> tree: git://git.cmpxchg.org/linux-mmotm.git master >>> head: ead058c4ec49752a4e0323368f1d695385c66020 >>> commit: af7abfba1161d2814301844fe11adac16910ea80 [8/285] hugetlbfs-check-for-pgoff-value-overflow-v3 >>> config: sh-defconfig (attached as .config) >>> compiler: sh4-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 >>> reproduce: >>> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross >>> chmod +x ~/bin/make.cross >>> git checkout af7abfba1161d2814301844fe11adac16910ea80 >>> # save the attached .config to linux build tree >>> make.cross ARCH=sh >>> >>> All warnings (new ones prefixed by >>): >>> >>> fs//hugetlbfs/inode.c: In function 'hugetlbfs_file_mmap': >>>>> fs//hugetlbfs/inode.c:118:36: warning: left shift count is negative [-Wshift-count-negative] >>> #define PGOFF_LOFFT_MAX (PAGE_MASK << (BITS_PER_LONG - (2 * PAGE_SHIFT) - 1)) >>> ^ >> >> BITS_PER_LONG = 32 (32bit config) >> PAGE_SHIFT = 16 (64K pages) >> This results in the negative shift value. >> >> I had proposed another (not so pretty way) to create the mask. >> >> #define PGOFF_LOFFT_MAX \ >> (((1UL << (PAGE_SHIFT + 1)) - 1) << (BITS_PER_LONG - (PAGE_SHIFT + 1))) >> >> This works for the above config, and should work for any. >> >> Andrew, how would you like me to update the patch? I can send a new >> version but know you have also made some changes for VM_WARN. Would >> you simply like a delta on top of the current patch? > > This? That will do it. Thank you, -- Mike Kravetz > > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Subject: hugetlbfs-check-for-pgoff-value-overflow-v3-fix-fix > > fix -ve left shift count on sh > > Cc: "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxxxx> > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > Cc: Nic Losby <blurbdust@xxxxxxxxx> > Cc: Yisheng Xie <xieyisheng1@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > fs/hugetlbfs/inode.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff -puN mm/hugetlb.c~hugetlbfs-check-for-pgoff-value-overflow-v3-fix-fix mm/hugetlb.c > diff -puN fs/hugetlbfs/inode.c~hugetlbfs-check-for-pgoff-value-overflow-v3-fix-fix fs/hugetlbfs/inode.c > --- a/fs/hugetlbfs/inode.c~hugetlbfs-check-for-pgoff-value-overflow-v3-fix-fix > +++ a/fs/hugetlbfs/inode.c > @@ -115,7 +115,8 @@ static void huge_pagevec_release(struct > * value. The extra bit (- 1 in the shift value) is to take the sign > * bit into account. > */ > -#define PGOFF_LOFFT_MAX (PAGE_MASK << (BITS_PER_LONG - (2 * PAGE_SHIFT) - 1)) > +#define PGOFF_LOFFT_MAX \ > + (((1UL << (PAGE_SHIFT + 1)) - 1) << (BITS_PER_LONG - (PAGE_SHIFT + 1))) > > static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) > { > _ >
