On Thu, 2016-09-08 at 07:48 -0600, Kani, Toshimitsu wrote: > On Thu, 2016-09-08 at 13:57 +0300, Kirill A. Shutemov wrote: > > > > On Mon, Aug 29, 2016 at 10:00:43PM +0000, Kani, Toshimitsu wrote: : > > > > > > Looking further, these shmem_huge handlings only check pre- > > > conditions. So, we should be able to make shmem_get_unmapped_are > > > a() as a wrapper, which checks such shmem-specific conitions, and > > > then call __thp_get_unmapped_area() for the actual work. All > > > DAX-specific checks are performed in thp_get_unmapped_area() as > > > well. We can make __thp_get_unmapped_area() as a common > > > function. > > > > > > I'd prefer to make such change as a separate item, > > > > Do you have plan to submit such change? > > Yes, I will submit the change once I finish testing. I found a bug in the current code, and need some clarification. The if-statement below is reverted. === diff --git a/mm/shmem.c b/mm/shmem.c index fd8b2b5..aec5b49 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1980,7 +1980,7 @@ unsigned long shmem_get_unmapped_area(struct file *file, return addr; sb = shm_mnt->mnt_sb; } - if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER) + if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER) return addr; } === Because of this bug, mounting tmpfs with "huge=never" enables huge page mappings, and "huge=always" or others disables it... The above simple change will change the default behavior, though. When "huge=" option is not specified, SHMEM_SB(sb)->huge is set to zero, which is SHMEM_HUGE_NEVER. Therefore, huge page mappings are enabled by default because of this bug. What's the intended default behavior of this feature? Thanks, -Toshi ��.n������g��� �a��� �&ޖ)���)��h���&������梷���� �Ǟ�m������)������^�����������v���O��zf������