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charset=us-ascii Content-Disposition: inline In-Reply-To: <20190801184244.3169074-7-songliubraving@fb.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Aug 01, 2019 at 11:42:43AM -0700, Song Liu wrote: > This patch is (hopefully) the first step to enable THP for non-shmem > filesystems. > > This patch enables an application to put part of its text sections to THP > via madvise, for example: > > madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE); > > We tried to reuse the logic for THP on tmpfs. > > Currently, write is not supported for non-shmem THP. khugepaged will only > process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests > (see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is > execve(). This requirement limits non-shmem THP to text sections. > > The next patch will handle writes, which would only happen when the all > the vmas with VM_DENYWRITE are unmapped. > > An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this > feature. > > Cc: Johannes Weiner > Acked-by: Rik van Riel > Acked-by: Kirill A. Shutemov > Signed-off-by: Song Liu Acked-by: Johannes Weiner